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Coastal fisheries in the South Pacific are reviewed, including descriptions of fisheries, catch composition, catch rates and fisheries biology studies conducted on target stocks. The most widely targeted coastal fish stocks are reef fishes and coastal pelagic fishes. The total coastal fisheries production from the region amounts to just over 100 000 tyr-1. About 80% of this production is from subsistence fishing.
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Oceanography and Marine Biology: an Annual Review 1996, 34, 395 – 531
© A. D. Ansell, R. N. Gibson and Margaret Barnes, Editors
UCL Press
1 Resource Assessment Section, Coastal Fisheries Programme, South Pacific
Commission BP D5, Noumea, New Caledonia.
2Centre for Tropical Coastal Management Studies, Department of Marine Sciences
and Coastal Management, University of Newcastle upon Tyne, England.
Abstract Coastal fisheries in the South Pacific are reviewed, including descriptions of
fisheries, catch composition, catch rates and fisheries biology studies conducted on target
stocks. The most widely targeted coastal fish stocks are reef fishes and coastal pelagic fishes.
Small pelagic species are important for subsistence and small-scale commercial fisheries.
Previously, small pelagic resources were important as a source of live bait for pole-and-line
tuna fishing, but this method is declining and only one large bait fishery is left in the region in
the Solomon Islands. The pole-and-line bait fisheries represent the only large-scale industrial
fisheries to have operated in the coral reef lagoons of the Pacific. Estuarine resources are of
major importance only in the large islands of Melanesia but are the staple diet of a relatively
large proportion of the total South Pacific population. Deep slope fish stocks form the basis of
only two commercial fisheries in the region and expansion of deep slope fishing comparable
with the 1970s and 1980s is unlikely to occur again. Commercial fisheries development is
currently orientated towards small- and medium-scale long-line fisheries for offshore pelagic
resources, where high value tunas and billfishes are caught for export markets.
The total coastal fisheries production from the region amounts to just over 100000 tyr-l, worth a
nominal US$262 000 000. About 80% of this production is from subsistence fishing. Just under
half the total annual commercial catch comes from fishing on coral reefs, which includes a
small tonnage of deep slope species. Invertebrates are the most valuable inshore fisheries
resources and these include sea-cucumbers, trochus and pearl oyster. Lobsters and mangrove
crabs form the basis of small-scale commercial fisheries, as also do penaeid shrimps, except in
PNG where they are caught in large quantities through trawling. Mariculture of shrimps is
becoming increasingly popular in the region and is a major industry in New Caledonia. The
greatest influence on coastal fisheries in the Pacific through the next decade is likely to come
from southeast and east Asia, where the demand for high value coastal fishes and invertebrates
has led to large scale depletions and has motivated entrepreneurs to seek stocks in the
neighbouring Pacific islands.
The archipelagos that are commonly referred to as the “South Pacific islands” are found in an
area roughly bounded by the tropics and lying between l30°E and 125°W (Fig. 1). There are
three racial and cultural subgroupings of the South Pacific, namely Melanesia, Micronesia and
Polynesia. The Melanesian islands are all relatively large archipelagos and include Papua New
Guinea (PNG), the Solomon Islands, Vanuatu and New Caledonia. Fiji lies halfway between
Melanesia in the west and the Polynesian islands of the central Pacific. Polynesia includes
American Samoa, the Cook Islands, French Polynesia, Niue, Pitcairn, Tokelau, Tonga, Tuvalu,
Wallis and Futuna and Western Samoa. The Micronesian islands lie mainly north of the equator
and include the Federated States of Micronesia — Yap (Fig. 2,117)3, Chuuk (Fig. 2, 16),
Pohnpei (Fig. 2, 79), Kosrae (Fig. 2, 43) — Guam, the Northern Mariana Islands, Marshall
Islands, Nauru, Palau, and Kiribati.
3. Numbers in parentheses refer to specific locations within countries or territories and are indicated on Figure 2.
Figure 1: Map of the South Pacific showing the countries and territories of the region. Easter Island (not shown) lies 2350 km to the east of
Pitcairn Island
On the periphery of this grouping are the subtropical islands belonging to: Australia — Lord
Howe (Fig. 2, 123), Norfolk Island (Fig. 2, 69); New Zealand — Kermadec Islands (Fig. 2,
124); Chile — Easter Island, Sala-y-Gomez; the USA — Hawaii, Johnston Island (Fig. 2, 37),
Wake Island; and Japan — Bonin (Fig. 2, 121), Kazan Islands (Fig. 2, 122). The remaining
islands comprise 15 independent countries, and seven territories belonging to either France, the
USA or the UK.
Some basic geographic and economic information on the South Pacific island countries and
territories is given in Table 1 (p. 409). Politically, these are all members of the South Pacific
Conference that was first convened in 1947 and which also includes the governments of New
Zealand, Australia, the United States, Britain and France. Fourteen independent island states,
with the addition of New Zealand and Australia, are also members of the South Pacific Forum
that was established in 1971. Both the Conference and the Forum have secretariats housed in
New Caledonia and Fiji, respectively. Both institutions support fisheries development and
management in the South Pacific: the Forum through the Solomon Islands based Forum
Fisheries Agency, which is concerned with managing access by distant water fishing nations to
the region’s tuna stocks, and the South Pacific Commission’s Fisheries Programme, which
performs research and development on tuna and coastal fisheries.
The combined area of the Exclusive Economic Zones (EEZs) of the South Pacific Commission
island members (from the Northern Mariana Islands to the Pitcairn Islands) is 29523000 km2,
but the land area of 550652 km2 is a small portion of this. Most of the land (84%) belongs to
PNG, with the other Melanesian islands and Fiji forming a further 14% of the total. For many of
the people of the South Pacific islands, particularly in land-deficient Micronesia and Polynesia,
fish is a staple source of animal protein. Although some islanders venture further offshore,
fisheries in the coastal zone have traditionally been the target of subsistence activity and
provide a major portion of the diet. Even with increasing urbanization and the shift in
preference to more imported western foods, fresh fish and invertebrates caught in coastal
waters continue to be a significant item in the diet of most Pacific islanders.
European exploration in the South Pacific during the last century and the Japanese entry during
the 1920s and 1930s was followed by interest in the commercial potential of invertebrate
resources in the region, such as in molluscs for mother-of-pearl and pearls, and sea-cucumbers
for bêche-de-mer production. Limited interest was shown in the finfish stocks of the region,
apart from some commercial exploitation of reef and tuna stocks in the Caroline Islands (Fig. 2,
14) during the 1930s. Following the first World War, however, fishing for tunas such as
skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (Thunnus obesus),
continued to expand until at present the annual landings from the waters in the South Pacific
Commission statistical area amount to about 991000 t worth in the region of US$1,460 000 000
(Anon. 1995). Following the Law of the Sea Conferences during the 1970s, the South Pacific
islands claimed sovereignty over EEZs extending 200 n.mi from the land. The present
commercial catches of tunas are made predominantly within the EEZs of the Pacific islands by
vessels from nations on the Pacific rim such as Japan, Taiwan, USA, China, Korea and the
Philippines (Anon. 1993a).
Impressive though the catches of tuna from the South Pacific are, they have limited impact on
the lives of the indigenous peoples of the region. Tuna are caught by highly mechanized
industrial fleets of purse seiner, long-line and pole-and-line vessels, often on the high seas. Less
than 7% of this tuna is caught by Pacific island vessels and only 25% of the total landings is
processed within the region, at canneries in the Solomon Islands, Fiji and American Samoa.
The remaining 75% of tuna landings is processed elsewhere by countries on the Pacific rim
(Anon. 1991a).
Figrure 2: Locations of places and geographical features in the South Pacific mentioned in the text. The first reference in the text
to a place or feature is followed by the corresponding number in parentheses.
By contrast, landings from the coastal zone are more modest, but they have a far greater social
and economic impact on the residents of the Pacific islands. Moreover, there is a more
immediate risk of over-exploiting the resources in the narrow coastal zones of many Pacific
island countries as populations increase and technology improves the fishing power of artisanal
fishers. Management of coastal fisheries is an increasingly important priority, but for this to
have any hope of success, information and feedback about the status and trends in coastal
fisheries must first be acquired by fisheries managers and administrators. The objectives of this
paper are:
1. to describe the various coastal fisheries of the South Pacific,
2. review the various biological studies and stock assessment methods used to provide
management information
3. to estimate the volume and value of these fisheries,
4. to discuss the possible future trends of these fisheries with respect to social, economic
and political developments in the region.
In general we have restricted our summaries to the South Pacific islands, but refer where
necessary to fisheries for the same or similar species on the periphery of the region, particularly
northeast Australia and Hawaii. Northeast Australia contains the Torres Straits (Fig. 2, 104) and
shares several important fisheries resources with Papua New Guinea. Hawaii, besides having
strong social and cultural links with Polynesia, also provides a biological analogue for the
subtropical islands in the south of the region about which relatively little is known.
The first regional fisheries meeting convened by the South Pacific Commission (Anon. 1952)
highlighted the lack of quantified information on South Pacific island fisheries. However,
because of the complexity and diffuse artisanal nature of coastal fisheries, together with the
gradual development of national fishery administrations, developments in fisheries production
from the coastal zone have not yet been comprehensively documented at the regional level. The
recent reviews of Pacific islands fishery resources published by the Forum Fisheries Agency
(Wright & Hill 1993) again highlighted the lack of information on the scale of harvests of fish
and marine organisms from the coastal zone. There is increasing concern about environmental
issues such as sea level rise from global warming and loss of biodiversity through excessive
exploitation of living natural resources. Fisheries production may be affected by sea level rise
and fisheries can contribute to local species depletions and extinctions through excessive
harvesting. This has already happened with the giant clam Tridacna gigas, which has been
driven to extinction in many of the islands of Micronesia, Vanuatu and probably New
Caledonia (Munro 1993) and Fiji (Lewis et al. 1988a), and with certain reef fish species in parts
of Micronesia (Myers 1989) and Polynesia (Bell 1980, Hooper 1985, Sims 1990). These
descriptions of fisheries and estimates of fisheries production are likely to be of interest to
workers in a variety of disciplines such as conservation, nutrition, economics, planning and
coastal zone management.
The physical geography of the South Pacific islands
An inventory of the islands of the South Pacific, which includes notes on geology and structure
of the different land masses in the region, is given by Douglas (1969). Two basic types of island
can be distinguished in the South Pacific, namely high islands and atolls. Land masses raised
from the ocean floor through vulcanicity and tectonic forces in time form high islands and
islands and develop fringing and coral reefs. Very young high volcanic islands such as Pagan in
the Northern Mariana Islands have relatively little reef development beyond encrusting coral
communities. Older high islands may have well developed fringing reefs. Such is the case with
Rarotonga (Fig. 2, 88) in the Cook Islands, Tahiti (Fig. 2, 96) and Bora Bora in the Society
Islands (Fig. 2, 94).
Nearly all the South Pacific islands lie within the tropics and so sea surface temperatures rarely
fall much below 20°C and may rise as high as 30°C during the course of a year. The coasts of
most Pacific islands are characterized by coral reefs, seagrass meadows and mangrove forests.
High islands contain the greatest number of reef zones and habitats. They are also the only
islands that have extensive fresh and brackish water habitats. Nutrient-rich rivers may carry
large quantities of silt resulting in highly productive, but turbid muddy habitats. Mangrove
forests thrive along the intertidal shorelines of estuaries and river mouths and seagrasses
flourish on silty inner reef flats and shallow lagoon floors.
High islands may subside, but the barrier and fringing reefs continue to grow and develop into
atolls, where a fringe of coral islands and reef surrounds a lagoon. Atolls lack rocky cliffs and
platforms as well as rivers and the well developed mangrove communities found in high islands
are either missing or poorly developed. They therefore lack many of the species associated with
these habitats. Occasionally, volcanic forces have raised atolls well above the sea surface to
produce highly porous limestone islands known as makateas. They lack rivers and have flat
tops and steep sides that may plunge directly into the sea, be undercut or be fringed by rocky
platforms or reef flats. Some of the countries and territories of the South Pacific consist
predominantly of only one island type such as atolls (Kiribati, Marshall Islands, Tuvalu),
makateas (Nauru, Niue) or high islands (Samoa, Vanuatu, Wallis and Futuna), but the
remainder are usually a mixture of atolls, high islands and makateas.
Few parts of the South Pacific have such extensive freshwater discharge that coral reef
development is inhibited over a wide area. The Gulf of Papua (Fig. 2, 32), the region’s major
estuarine area, has coral reefs at the western and eastern margins, where the influence of the
massive freshwater influx from drainage of the mountainous hinterland of Papua New Guinea
is reduced. Elsewhere on the smaller islands of the Pacific, the outflow of rivers has a minor
influence on reef development.
The corals and coral reefs of the Pacific islands are described in Wells & Jenkins (1988) but the
species of hermatypic or reef building corals in the South Pacific have been fully described only
for Australia (Veron 1986), with over 330 species contained in 70 genera. The number of
species of coral declines in an easterly direction across the Pacific in common with the
distribution of fish and invertebrate species (see p. 404) so that there are only 30 genera present
in the Society Islands of French Polynesia and 10 genera in the Marquesa Islands (Fig. 2, 56)
and the Pitcairn Islands. All forms of coral reef development can be found in the South Pacific
including large barrier reefs around New Caledonia and in Fiji, extensive fringing reefs,
particularly around the large Melanesian islands, and patch and submerged reefs, banks and
shoals throughout the region.
Mangrove forests (especially Rhizophora spp., Bruguiera spp., and Avicennia spp.) are
prevalent in estuarine areas but sediment build up may also permit establishment of mangrove
trees and bushes on the reef flat. On atolls, mangroves may be absent or present only in thin
patches. A directory of Pacific island wetlands, including mangrove forests, has been compiled
by Scott (1993), while the distribution, environmental aspects and ecology of Pacific islands
mangroves is reviewed by Woodroffe (1987), and included in a global review of tropical
marine ecosystems by Hatcher et al. (1989). Apart from the usefulness of the wood for building,
charcoal and tannin, mangrove forests act to stabilize are as where physical sedimentation
is occurring and, from a fisheries perspective, are important as nursery grounds for peneaeid
shrimps and some inshore fish species, and form the habitat for some commercially valuable
crustaceans. Extensive mangrove forests area feature of high islands in the western Pacific,
particularly the Melanesian islands and Fiji. The natural eastern limit of mangroves in the
Pacific is American Samoa, although Rhizophora stylosa was introduced to the Society Islands
of French Polynesia in the 1970s. Mangroves are also absent from Wallis and Futuna, Tokelau
and the Phoenix (Fig. 2, 127) and Line Islands (Fig. 2, 128) of Kiribati.
Seagrasses are common in all marine ecosystems and are a regular feature of most of the
inshore areas in the Pacific islands. According to Hatcher et al. (1989), seagrasses stabilize
sediments because leaves slow current flow, thus increasing sedimentation of particles. The
roots and rhizomes form a complex matrix that binds sediments and stops erosion. Seagrass
beds are the habitat of certain commercially valuable shrimps, and provide food for reef-
associated species such as surgeonfishes (Acanthuridae) and rabbitfishes (Siganidae).
Seagrasses are also important sources of nutrition for higher vertebrates such as dugongs and
green turtles. A concise summary of the seagrass species found in the western tropical South
Pacific is given by Coles & Kuo (in press), and Wells & Jenkins (1988) include information on
seagrass beds in association with the coral reefs of the Pacific islands.
Climate and the marine environment of the South Pacific islands
Average annual rainfall in the South Pacific ranges from just over 1000 mm in New Caledonia
to 5000 mm in Pohnpei and Kosrae States in the Federated States of Micronesia. The large high
island archipelagos of Melanesia may have quite different rainfall regimes on different parts of
the same island or between locations on different islands. For example, the rainfall in the Fijian
capital Suva is about 3200 mm per year while that of Nadi, some 110 km to the west, is about
1900 mm per year. In PNG, Abeyasekera (1987) was able to distinguish three distinct rainfall
regimes; namely, are as where rainfall is constant throughout the year, areas where rainfall
peaks between May and August and areas where rainfall is highest from December to March.
High islands tend to retain moisture bearing clouds and have higher annual rainfall regimes
than atolls and other low islands. However, mountains may form rain-shadow are as that
receive rain only at certain times of the year as is the case with the region around the PNG
capital, Port Moresby (Fig. 2, 80), which experiences strong rainfall only during November to
March and has an annual total of about 1200 mm per year.
For most of the Pacific islands rainfall typically ranges from 2000 to 3500 mmyr-l. Law islands
such as makateas and atolls tend to have less rainfall and may suffer prolonged droughts.
Furthermore, when rain does fall on coral islands and makateas where there is no major
catchment area, there is little allochthonous nutrient input into surrounding coastal waters and
lagoons. Lagoons and embayments around high islands in the South Pacific are therefore likely
to be more productive than atoll lagoons. The productivity of high-island coastal waters,
particularly where there are lagoons and sheltered waters, is possibly reflected in the greater
abundance of small pelagic fishes such as anchovies, sprats, sardines, scads, mackerels and
fusiliers (Anon. 1984a). In addition, the range of different environments that can be found in the
immediate vicinity of the coasts of high islands also contributes to the greater range of
biodiversity found in such locations.
Climatic seasonality in the South Pacific is more pronounced at higher latitudes. Even at or
close to the equator there may be seasonal effects from the amount of rain carried by the
prevailing winds. Most of the region is influenced by winds that blow from the south and east
(the Southeast Trades), but for about 4 – 5 months during the northern winter, the prevailing
winds in the western Pacific blow from the north and west (Northwest Monsoon). Rainfall
tends to be highest during the summer and autumn months both north and south of the quator.
This is well illustrated by comparing the average monthly rainfall in Saipan (Fig. 2, 91) in the
Northern Mariana Islands with that of Western Samoa. Both locations are at roughly the same
latitude north and south of the equator with the same average mean temperature (26°C),
although Samoa is wetter with an average annual rainfall of 2900 mm compared with 2200 mm
in Saipan. Rainfall in Samoa reaches a maximum between November and February, while in
Saipan rainfall peaks between July and October.
Information on the hydrographic characteristics of South Pacific marine environments has been
summarized from various sources by Wauthy (1986). The waters that form the surface layer of
the tropical west and central Pacific enter into the transpacific intertropical circulation from the
eastern boundaries of two subtropical anticyclonic gyres, where the coastal upwelling of
California and Peru provide enrichment of nutrient rich subsurface waters. The waters remain
on the surface and the thickness well established thermocline. As these waters move from east
to west they grow warmer and more impoverished as nutrients are consumed by photosynthesis
and particulate materials are sedimented. Limited primary production continues on the basis of
partial re-mineralization within the isolated upper surface layer of the water column.
Nutrient-depletion leads to very clear blue oceanic water in which suspended particles are
depleted and living organisms are scarce. The term “oceanic desert” has been used by Lisitzin
(in Wauthy 1986) to describe these nutrient poor-waters. Primary productivity in the photic
zone ranges on average from 20 to 50 gCm-2yr-1(FAO 1972). Upwelling is one mechanism by
which impoverished tropical waters can be enriched with nutrients from the subsurface waters
and this has been observed at the equator. Another mechanism whereby subsurface
nutrient-rich waters reach the euphotic zone involves shallowing of the thermocline at 10°N
and 10°S, at the edge of the equatorial counter currents. In the South Pacific, nutrient inputs
from precipitation and runoff are of major significance only in the waters surrounding the large
island archipelagos of Melanesia where highlands are extensive and rainfall is very heavy. Not
surprisingly, the highest oceanic primary productivities in the region (90 — 180 gCm-2yr-l) are
found on the shelf area of the Gulf of Papua which receives much of the drainage from PNG
highlands region.
Combination of various physical factors results in the accumulation in the tropical Pacific of a
thick surface layer of warm water west of 180°. This accumulation forms one of the
pre-conditions necessary for the generation of cyclones or hurricanes that are a common
meteorological phenomenon in the South Pacific. The second pre-condition is the existence of a
cyclonic-like convergence in the lower layers of the atmosphere that can be found in the
western tropical Pacific between the equatorial monsoon winds from the west and the easterly
trade winds. In the northwest tropical Pacific, cyclones form most frequently between June and
November, and are most frequent in August/September, with an average of 18 per year. South
of the equator, cyclones occur from December to April and are less frequent than in the
northwest, with an average of four per year (Wauthy 1986).
Large-scale oceanic events such as the El Niño Southern Oscillation (ENSO) also influence the
coastal marine environment of the South Pacific islands. The Southern Oscillation Index is the
difference in atmospheric pressure between Tahiti and Darwin, which is usually positive
due to the low pressure area over Indonesia and Australia. During an ENSO episode, the
pressure gradient reverses and becomes negative for a prolonged period with a consequent shift
in climatic and oceanographic conditions. The easterly trade winds weaken and westerly winds
are observed over parts of the equatorial western Pacific. The area of warm water usually
associated with the western tropical Pacific is displaced eastward over the central and eastern
Pacific region and the ocean waters of the western Pacific cool. This phenomenon results in the
appearance of an anomalous warm ocean current off the coasts of Peru and Ecuador around the
Christmas season and hence was named by Peruvian fishermen “El Niño”, the familiar
diminutive Spanish term for the infant Christ.
This major climatic shift produces unseasonal droughts in the western Pacific and unseasonal
rains in the central and eastern Pacific. Information from commercial tuna fisheries in the South
Pacific and pelagic and demersal fisheries in South America suggests that ENSO events can,
depending on species, have both negative and positive effects on catch ability and apparent
abundance. In the western and tropical Pacific, the abundance of surface skipjack and yellowfin
tuna stocks shifts eastwards during an ENSO episode. This can be inferred from the
concentration of fishing effort by tuna purse-seine vessels, which during normal years
concentrate to the West of 160°E line of longitude and to the east of this line during an ENSO
event (Anon. 1995). Little is known at present about how ENSO events affect coastal fish and
invertebrate stocks in the South Pacific due to the lack of any suitable time series of data. It is
likely, however, that such a large scale anomaly will have an influence on productivity and
recruitment, especially in those species with long oceanic pelagic larval stages, and those reef
species that are sensitive to anomalous water levels during spawning or recruitment.
There may be other long-term climatic cycles in the Pacific region that will influence the
productivity and abundance of marine organisms. Polovina et al. (1994) describe such an event
in the Hawaiian Islands that began in the mid 1970s and ended in the late 1980s. Over a 10-year
period, this climatic event promoted the movement of nutrient-rich deep ocean water into the
euphotic zone during the first quarter of the year. This in turn resulted in higher survival of fish,
crustaceans, seals and sea birds. The decline in the event was followed by declines in the
recruitment and abundance of fish, crustaceans, birds and seals. During this event an important
commercial lobster fishery in the Northwest Hawaiian Islands (Fig. 2, 72) expanded rapidly in
the mid 1980s then declined as recruitment to the population was markedly reduced, despite the
efforts of fisheries managers to promote sustainable yields from the fishery.
Fisheries resources of the South Pacific
Marine resources in the context of this paper refer mainly to marine organisms that are caught
and collected for food, but also include molluscs such as trochus, green snail and pearl oysters
where harvests are mainly for the shells. As the majority of the South Pacific islands are atolls
and small islands surrounded by coral reefs, the principal targets of nearshore fisheries in the
region are fauna associated with coral reefs and lagoons. As stated previously, the only country
with extensive estuaries is PNG, whereas the other large Melanesian islands have smaller more
limited estuarine environments. Species diversity of fishes, molluscs, crustaceans and
echinoderms declines in an easterly direction across the Pacific.
There are about 2 500 reef and inshore fishes in the Philippines, at the centre of the IndoPacific
faunal continuum, compared with only 125 in Easter Island at the eastern margin of the region
(Myers 1989). This species gradient appears to be related to the position of the South Pacific
islands in relation to the Pacific Plate, the largest of the Earth’s lithospheric plates. The Pacific
islands lie on or along the margin of this geological structure. The biogeography of the South
Pacific region and species distributions in relation to the Pacific Plate have been discussed by
Springer (1982) and Myers (1989). Pacific islanders may consume a wide variety of reef fishes,
including snappers (Lutjanidae), emperors (Lethrinidae), groupers (Serranidae), parrotfishes
(Scaridae), mullet (Mugilidae), surgeonfishes (Acanthuridae), jacks (Carangidae), and other
nearshore pelagic species such as scads (Carangidae), tunas and mackerels (Scombridae).
Pacific islanders will also consume small species such as squirrelfishes (Holocentridae),
hawkfishes (Cirrhitidae) and some of the sm aller surgeonfish species. Observations on a
typical small scale commercial reef fishery in the western and central part of the South Pacific
may record between 200 and 300 species in the catch, although it is likely that only a few
species will dominate landings. The fishes commonly associated with mangrove and estuarine
ecosystems in Melanesia are listed by Kailola & Wilson (1978), Collette (1983), Quinn & Kojis
(1986), Blaber & Milton (1990) and Thollot (1992). Species commonly caught in the large
estuarine and mangrove areas include barramundi (Centropomidae), catfishes (Ariidae),
threadfins (Polynemidae), ponyfishes (Liognathidae), clupeoids (Engraulidae & Clupeidae),
jewfishes (Sciaenidae) and grunters (Theraponidae).
South Pacific islanders also use a great variety of molluscs for food and for their shells.
Cernhorsky (1967, 1972) records over 1000 species of shell bearing molluscs from the South
Pacific. In addition to these are the various cephalopods such as squids, cuttlefish and octopus
that are caught in the nearshore zone. Several molluscs are of prime commercial value in the
region and these include trochus (Trochus niloticus), green snail (Turbo marmoratus) and
black-lip pearl oyster (Pinctada margaritifera). All these species are harvested primarily for
mother-of-pearl used for button manufacture and furniture inlay. The black-lip pearl oyster, as
the name suggests, is also valuable for the production of a form of pearl that is dark silvery-grey
in colour and was originally collected from wild populations, but is increasingly being cultured
artificially. A wide variety of molluscs is also consumed for food and these are discussed in
detail below.
There are an estimated 300 species of shallow water holothurians in the Indo-Pacific region that
account for about 27% of the echinoderm fauna in the Pacific islands (Guille et al. 1986).
Holothurians form part of the subsistence diet of many Pacific islanders, although certain
species are commercially valuable as a dried product known as bêche-de-mer, or trepang, that is
exported, mainly to Asia. There are at least 22 species of holothurians which are caught for
bêche-de-mer production in the South Pacific and these belong to the genera Actinopyga,
Holothuria, Stichopus, Theloneta and Bohadschia (Preston 1993, Adams et al. in press).
Pacific islanders also consume a variety of crustaceans found in the nearshore zone including
crabs, lobsters and shrimps. The mud crab (Scylla serrata) is widely distributed in the region
and this is caught for commercial sale as well as for subsistence. Other reef dwelling crabs such
as the three spot reef crab (Carpilius maculatus), the sand crab (Portunus pelgicus) and the red
crab (Etisus splendidus) are also consumed for subsistence. Land crabs such as the coconut crab
(Birgus latro) have traditionally been a component of subsistence catches and may be caught
commercially, particularly where there is a developing tourist industry. Other smaller land
crabs such as Cardisoma carnifex and hermit crabs are a seasonally important subsitence
Several spiny lobster species are found in the South Pacific including Panulirus penicillatus, P.
longipes, P. versicolor and P. ornatus, found mainly on tropical reefs; and P. marginatus and P.
pascuensis found on subtropical reefs. These and the related slipper lobsters (Scyllaridae) are
captured both for subsistence and commercial purposes. Other crustaceans that are harvested
from the coastal zone include mantis shrimps (Squilla spp.), mud lobsters (Thalassina
anomala) and penaeid shrimps. Over 40 species of penaeid shrimps have been identified from
the waters of PNG (Rapson & Mclntosh 1972) but the most abundant is the banana shrimp,
Penaeus merguiensis. Also commonly captured are tiger shrimps, P. monodon and P.
semisulcatus, and the endeavour shrimps, Metapenaeus ensis and M. demani. Elsewhere, such
as Fiji, Penaeus canaliculatus and Metapenaeus anchistus are locally abundant (Choy 1988),
while species such as Penaeus semisulcatus and Metapenaeus ensis, which are species of minor
importance in PNG, are abundant in the lagoon of Tongatapu (Fig. 2, 103), the main island of
Tonga (Braley 1979).
Other invertebrates and marine organisms that are consumed regularly or as delicacies by
Pacific islanders include chitons, sea-hares, marine worms and seaweeds. Populations of the
marine polychaete worm, Eunice viridis, (palolo in Samoan and balolo in Fijian) undergo
periods of mass spawning in coastal waters once a year during full moon periods. The gamete
bearing segments of the worms rise to the surface where they can be collected by coastal
villagers and are regarded as a great delicacy in parts of the the Pacific, especially Samoa.
Fishing methods
Subsistence and artisanal fishing
There is a rich tradition of fishing techniques, beliefs and customs associated with fishing in the
South Pacific islands and many of these have been described in anthropological studies made
over the last 200 years (e.g. Anell 1955). In this review, however, we are concerned mainly with
contemporary fishing practices and will describe those gears and fishing methods that are
widely used on a regular basis in the region. Most coastal fisheries in the South Pacific are
characterized by small-scale artisanal fishing methods. A considerable amount of fishing takes
place from the shore or in shallow waters without the use of fishing vessels. Where fishing
vessels are used, these are generally small, either non-powered canoes or canoes and dinghies
powered by outboard motors and, to a lesser extent, by sail. Larger vessels of 8 – 20 m in length,
powered by inboard diesel engines, are used for commercial fishing for demersal species
beyond the reef slope, and for catching tuna on the open ocean.
Common gears include hooks-and-lines, traps (fixed and moveable), seine and gill nets, and
spears. Hooks-and-lines can be deployed in a variety of ways, as simple droplines to catch
demersal fishes, as bottom and surface long-lines to catch demersal and pelagic fishes
respectively, and towed with baits and lures to troll for pelagic fishes. Traditionally, hooks were
fashioned from shells, bones and wood, whereas lines were made from coconut or other plant
fibre. These traditional materials have generally been superseded by monofilament lines and
metal J or circle hooks. Traditional shell lures are still used in some locations such as French
Polynesia (Chapman & Cusack 1988a) to troll for tuna and other large pelagic species.
Hand-line or drop-line fishing in shallow coastal waters is a common subsistence and
recreational fishing method in most of the Pacific. Hand-lines can be deployed on reefs, in
estuaries and on the shelf to catch demersal species. Hand-lines are also used in midwater to
catch small pelagic fishes such as bigeye scads or round scads, using baits or lures. Coastal
fishermen will also use hand-lines in midwater to catch tuna and other large pelagic species
such as rainbow runner (Elagatis bipinnulatus) and wahoo (Acanthocybium solandri).
Commercial drop-lines for demersal species such as snappers and groupers on the deep reef
slope or on banks and seamounts are mounted on reels to aid hauling from depths between 100
and 400 m. A common design of hand-reel for such operations was developed in Western
Samoa by the Food and Agricultural Organisation of the United Nations and propagated
throughout the region by the South Pacific Commission (Dalzell & Preston 1992). Long-line
fishing has also been used to catch demersal species from the deep reef slopes, particularly in
Fiji, where long-lines of between 500 and 1000 hooks were set on offshore banks and
seamounts. Similar sized surface long-lines are presently employed to catch tuna, particularly
large yellowfin and big eye tunas that have a high value on overseas markets in Japan and
Gill netting, beach seining and drive-in netting are conducted both in coralline and estuarine
areas of the Pacific. Nets were traditionally manufactured by Pacific islanders from plant fibres
such as coconut and pandanus, but such nets are now rarely made and used except in the most
remote islands. Gill net fishing is practised on reefs and lagoons in the Pacific and in some
areas, such as Kiribati, has become one of the most popular fishing methods in this archipelago.
Gill net fishing is also widely practised in estuarine areas of the Pacific. In most instances nets
are set from dinghies and canoes for periods of between 1 h and an overnight soak. The major
drawback for fishermen with gill nets in both reefs and estuaries is damage to the nets from
Drive-in net fishing is commonly practised around many islands of the Pacific. Nets are set in
an area of shallow water, on a reef plateau or in the lagoon and fish are driven by scare lines and
swimmers into the net. The fish may be concentrated at one end of the net for hauling, or
swimmers armed with spears may enter to kill and collect fish. A description of this type of
fishing operation is given in Smith & Dalzell (1993). Surround netting involves setting a net
around an area of coral or around a school of fish. The fish are then caught by swimmers who
enter the net enclosure carrying spears. Beach seines may be deployed in lagoon waters to trap
schooling fishes such as scads, small jacks, herrings and halfbeaks, while barrier nets can be
strung across reef passages and channels to trap fish as they return from feeding on the reef
Other common net fishing techniques include cast netting and scoop netting for flying fishes.
Cast nets are used in coastal shallows by fishermen to catch schooling species such as mullet
and rabbitfishes. The fishermen stalk the school, which often creates a ripple pattern on the
water surface, and attempt to cast a circular weighted net over the school and thus entangle the
fish in the mesh. Hand-held scoop nets are commonly used in Polynesia to catch flying fishes at
night. Fishermen chase the flying fishes over the water surface, spotting them by torch light and
catching them in the scoop nets before the fish can launch themselves into flight (Gillett &
Ianelli 1991).
Spears may be single- or multiple-pronged, traditionally made from wood and bone but
nowadays made of steel. Spear fishing is conducted both above water and below. Spear
fishermen may target fish from land or boat using spears and arrows, or by diving beneath the
water with hand spears and spear guns. Captured fish are threaded on a line wrapped around the
diver’s waist, on a line trailing behind the diver or even towed in a galvanized basin buoyed by
an old car inner-rube, as a precaution against shark attack. The development of masks, fins,
SCUBA gear, steel spears and spear guns has meant that the fishing power of the
spear-fishermen has greatly increased. Some spear fisheries are very specialized such as that for
dolphinfish (Coryphaena hippurus) in French Polynesia. High-powered launches will chase the
dolphinfish along the surface, as this species will usually not dive to escape pursuit. As the fish
tires the fisherman harpoons it with a multiple-pronged barbed spear.
Fixed or stationary traps are a common feature in coastal areas of the South Pacific. The
simplest of these structures are V-shaped stone and stick enclosures with an entrance that faces
the shore, as found, for example, in PNG (Hulo 1984) and Cook Islands (Baquie 1977). They
may be more complex structures comprising a series of leaders or barriers that guide the fish
into a series of interconnecting chambers. The chambers terminate in a single catching chamber
where the fishes may be netted or speared. These more complex structures are found in French
Polynesia (Grand 1985), Guam (Amesbury et al. 1986), Tonga (Halapua 1982) and Palau
(Johannes 1981). Fixed barrier traps take advantage of the tidal foraging migration of different
species of fish to effect capture. Fishes that have been feeding on the reef flat or in estuarine
shallows will follow the receding tide into deeper water. When they encounter a fence they will
swim along it and concentrate in a chamber or net where they can be caught.
The regular use of portable fish traps appears to be confirmed mainly to Micronesia and parts of
French Polynesia, although bamboo and mangrove wood traps were traditionally deployed in
coastal areas of the South Pacific (see for example Koch 1961 and contributions in Quinn et al.
1984). Johannes (1981) describes the deployment of portable fish traps in the shallow coastal
waters of Palau, and Smith & Dalzell (1993) give a brief account of trap fishing in Woleai Atoll
(Fig. 2, 115), which lies to the east of Yap. Traps in Palau are made either of traditional
materials, such as sticks and vines, or welded steel bars and chicken wire and are used to catch
a variety of reef fish. Traditional stick and vine traps are also used on Woleai to catch reef fishes
and one type of trap is specifically designed to catch the goatfish (Mulloides flavolineatus)
when seasonally abundant in the lagoon. Cubiform wire mesh traps are deployed in the lagoon
of Rangiroa Atoll (Fig. 2, 88), Tuamotu Archipelago in French Polynesia, to catch
surgeonfishes, especially Acanthurus xanthopterus and A. bleekeri.
A variety of other fishing and collecting activities are conducted along Pacific shorelines and
reefs in addition to fishing with spears, lines, traps and nets. Kite fishing is still employed in
some parts of the region to catch needle fish (Belonidae) (Johannes 1981, Hulo 1984). A spider
web lure is towed behind a canoe beneath a Pandanus-leaf kite. Needle fish or longtoms, which
prey mainly on small pelagic fish, will attack the web lure as it skips over the sea surface and
become snared as their teeth tangle in the spider web. Molluscs and echinoderms can be picked
off the reef at low tide, and octopus may be drawn out of holes in the reef with a metal hook. In
most locations molluscs, crustaceans, sea-cucumbers and seaurchins, collected mainly by
women and children, may form a significant fraction of the total reef harvest (Wass 1982,
Mathews & Oiterong 1991, Rawlinson et al. 1994).
Larger predatory fishes may also be caught in nooses at the water surface. Migrant phosphate
mine workers from Tuvalu and Kiribati have been observed to noose wahoo (Acanthocybium
solandri) that aggregate around mooring buoys on Nauru (Cusack 1987). A bamboo pole is
rigged with a short line and a teaser bait, usually a flying fish, attached to one end. A second
pole has a running noose attached to one end. The bait is splashed on the water surface until a
wahoo responds and begins to make passes at it. The fisherman then attempts to position the
noose between the wahoo and the bait so that the fish will pass through and can be snared.
Perhaps the most spectacular example of this type of fishing is the catching of reef sharks by
fishermen from Kontu village on New Ireland (Fig. 2, 67), PNG (Kohnke 1974). Reef sharks
are attracted or called by the use of a coconut shell rattle shaken in the water, which draws the
shark to the canoe. The shark is coaxed through a cane noose with a reef fish (preferably
rabbitfish). The noose is attached to a wooden propeller that spins as the shark dives, tightening
the cane around the gills and suffocating it.
Industrial scale Fisheries
Most of the islands of the South Pacific have steeply shelving slopes and are surrounded by
coral, unsuitable for conducting trawl fishing. Trawls can be deployed on the soft bottoms of
estuarine areas of the bigger islands, however, for catching shrimps and demersal fishes. Only
one South Pacific country, PNG, has established commercial trawl fisheries. The most
important of these is the trawler fleet in the Gulf of Papua that numbers between 10 and 20
vessels and targets stocks of penaeid shrimps. The trawlers displace about 150 gross tonnes
(gr.t.) and are twin rigged with two 12-fathom (footrope) nets. This fleet fishes 24 h per day
throughout the year in the northern and eastern Gulf of Papua and has been operational since
1969. In the early 1980s, a smaller shrimp fishery, limited in most years to two vessels,
commenced in Orangerie Bay (Fig. 2, 74) on the southeast Papuan coast.
The lagoons and sheltered embayments of the Pacific islands often contain small pelagic fishes
that can be used as live bait for pole-and-line tuna fishing. The small pelagic resource is usually
a complex of clupeoid species including anchovies (Engraulidae) and sprats, sardines and
herrings (Clupeidae) as well as small scads (Carangidae), mackerel (Scombridae), silversides
(Atherinidae) and fusiliers (Caesionidae). The small gracile anchovies belonging to the genera
Encrasicholina and Stolephorus, and the sprats of the genus Spratelloides, are the principal
targets of tuna live-bait fisheries in the South Pacific.
Fleets of pole-and-line tuna vessels (mainly from Okinawa) have operated from Palau, PNG,
Kiribati, Fiji, New Caledonia and the Solomon Islands. A typical vessel is about 20 m in length
and displaces about 60 gr.t. Catches of live bait are made from the pole-and-line boats using a
stick-held dip net or bouke-ami. Catches are made at night after concentrating the bait fishes
around powerful submersible lights. The captured bait is concentrated in one end of the net and
loaded into buckets for transfer to tanks set in the deck of the tuna vessel. The bouke-ami is then
stowed while the tuna vessel sails for the open sea to pursue tuna schools. The deployment and
operation of the bouke-ami is described in detail by Muyard (1980). Pole-and-line tuna fishing
has largely been superseded by purse-seining and is now confined chiefly to the Solomon
Islands and Fiji fleets with small fisheries in Tuvalu and Kiribati (Anon. 1995).
Finfish fisheries
Reef fisheries
Fishing on coral reefs occurs in all the countries and territories of the South Pacific and most of
the techniques employed are comparable between the different locations. We have therefore not
described at length the reef fisheries in each country; instead we have summarized the relevant
literature in Table 1 and selected examples that might be described as typical of a country
or sub-region within the South Pacific. Without exception, all reef fisheries in the South Pacific
are small-scale fisheries using simple non-mechanized gears. The major differences between
Pacific island reef fisheries are the range of gears used, the emphasis on particular gears and
most importantly, the fishing pressure applied to reef fish stocks. Fish does not appear to be as
important in subsistence diets in the large island archipelagos of Melanesia as in the smaller
resource-limited countries of Micronesia and Polynesia (Coyne et al. 1984). The annual per
capita production for the Pacific islands can be approximated from the figures in Table 27 (p.
499) and the population figures in Table 1. This ranges from 7 — 40 kg or a mean of 23 kg for
the Melanesian islands, while for the Polynesian and Micronesian islands the ranges are 6 —
121 and 4 — 170 kg, with means of 61 and 63 kg respectively. Fishing effort on all coastal
fisheries stocks, including reef fishes, is substantially greater in the Micronesian and
Polynesian islands, in comparison with the Melanesian islands.
In all but the remotest islands, reef and other coastal fisheries have both a subsistence and a
commercial component. The size of the commercial fisheries sector is dependent on the degree
of urbanization of the island population, the amount of available land for agriculture and the
development of the cash economy. Subsistence reef fishing methods tend to be very simple and
in most of the examples given in Table 2, fishes caught by hand-lines and spears make up most
of the subsistence catch. Larger volumes of fish can be generated through the use of community
fishing methods such as group spearing and drive-in net fishing and these methods may be
employed when greater amounts of fish are required for occasions such as village feasts.
Commercial reef fisheries also include hand-lines and spears but in the examples in Table 2
there is a greater emphasis on the use of nets such as gill nets, drive-in nets and fish corrals.
Table 1: Geographical and economic statistics for the countries and territories of the
South Pacific.
Annual Per
area Population Pop. growth Total GDP capita
Country (km2) (1994) density rate (%) (US$ 000) GDP
American Samoa 200 54 600 273 3.7 203 125.3 5194.8
Cook Islands 237 19 100 81 1.1 70 095.5 4052.1
Federated States of 701 105 900 151 3.0 246 011.2 2652
Micronesia (FSM)
Fiji 18 272 777 700 43 2.0 1,620 707.4 2118.5
French Polynesia 3521 218 000 62 2.5 3,202 764.2 15 305.2
Guam 541 146 700 271 2.3 1,180427.8 9637.7
Kiribati 810 78 300 97 2.3 33 875.4 468
Marshall Islands 181 54 069 299 4.0 74 735.8 1556
Nauru 21 10 600 505 2.9 160 875 17 486
Niue 259 2 100 8 –2.4 6891.6 3077.8
Northern Mariana Is 471 56 600 120 9.5 571 297 10 094
New Caledonia 19 103 182 200 10 2.0 2.125 919.6 12 753
Palau 488 16 500 34 2.2 49 367.1 3247.4
Papua New Guinea 462 243 3,951 500 9 2.3 5,670 260.7 1468
Pitcairn 5 60 12
Solomon Islands 27 556 367 400 13 3.4 262 526.2 738.7
Tokelau 10 1500 150 –1.3 624 372.8
Tonga 747 98300 132 0.5 138 035 1415.7
Tuvalu 26 9500 365 1.7 64 187.2 7053.5
Vanuatu 12 190 164 100 13 2.8 208 878.5 1308.8
Wallis & Futuna 255 14 400 56 1.3
Western Samoa 2935 163 500 56 0.5 165 885.7 1017.9
Table 2: Summary of literature sources describing reef fisheries in the Pacific islands.
Country Location Reference
Australia Torres Straits Johannes & MacFarlane (eds) 1991
American Samoa Tutuila Craig et al. 1993, Saucerman 1994
Cook Islands Rarotonga Baquie 1977
Palmerston Anon. 1988a
Federated States of Micronesia Smith 1992a
Woleai Atoll Smith & Dalzell 1993
Kosrae Wilson & Hamilton 1992
Yap Uwate 1987
Fiji Rotuma Anon. 1983a
Rabi (Fig. 2, 84) Anon. 1983b
Dravuni (Fig. 2, 20) Emery & Winterbottom 1991,
South & East Fiji Jennings & Polunin 1995a,
Viti Levu Rawlinson et al. 1994
French polynesia Tuamotu Archipelago Grand 1983, 1985, Stein 1988
Kaukura Grand 1983
Rangiroa Grand et al. 1983
Tikehau Morize 1985, Caillart 1988a
Guam Amesbury et al. 1986, Katnick 1982,
Knudson 1987, Myers 1993
Hawaii Smith 1994
Kiribati Gilbert Islands Mees et al. 1988
Tarawa Yeeting & Wright 1989
Marshall Islands Smith 1992b
Nauru Dalzell & Debao 1994
New Caledonia Loubens 1978a, Leblic & Teulieres
1987, Anon. 1988b, 1994a
Niue Dalzell et al. 1992
Northern Mariana Islands Hamm et al. 1994
Palau Johannes 1981 1991, Nichols 1991,
Mathews & Oiterong 1991, Kitalong
& Dalzell 1994
Papua New Guinea Kavieng Wright & Richards 1985, Dalzell &
Wright 1990
Port Moresby Lock 1986a, b, c, d
Western Manus Chapau & Lokani 1986
Pitcairn Islands Pitcairn Island Sharples 1994
Solomon Islands Marovo Lagoon Hviding 1988
Roviana, Tulagi and Vona Vona Leqata et al. 1990, Blaber et al 1990
Gizo Sasabule 1991
Roviana Gina-Whewell 1994
Ontong Java Bayliss-Smith 1974
Tokelau Fakaofo (Fig. 2, 23) Hooper 1985
Tonga Tongatapu Zann 1981, Halapua 1982, Munro
Tuvalu Funafuti Zann 1980, Patiale & Dalzell 1990
Nanumea Chambers 1984
Vanuatu David & Cillauren 1989
Wallis & Futuna Wallis Taumaia & Cusack 1988
Futuna (Fig. 2, 27) Galzin 1985
Western Samoa Upolu Helm 1992, Zann et al. 1991
In PNG, the largest of the Melanesian archipelagos, fishing activity, including subsistence
fishing, is very limited around most of the coast and this is true of fishing on coral reefs (Dalzell
& Wright 1986). Wright & Richard’s (1985) study of the Tigak Islands (Fig. 2, 100) reef fishery
in northern PNG is a good descriptive account of subsistence and commercial reef fishing
applicable to most coral reef areas of PNG and probably most of rural Melanesia. Almost all the
subsistence catch came from hand-line fishing and spear fishing from canoes and dinghies.
Wright & Richards note that catches are made to satisfy only immediate food requirements and
nets are rarely employed as their use requires more organization and yields a large surplus
catch. There is no full-time commercial reef fishery in the Tigak Islands. When cash is required,
villagers will occasionally catch relatively large volumes of fish for sale in the main urban
centre of Kavieng (Fig. 2, 39), mostly through gill and surround netting. The main influences on
the volume of commercial landings by individual villages were distance from markets in
Kavieng and the price of the main agricultural commodity, copra (Dalzell & Wright 1990).
The main motivation for commercial fishing in the Melanesian islands is lack of any
agricultural land. Daugo Island (Fig. 2, 19) is a small barren coral island on the Papuan Barrier
Reef with poor top soil, few trees and bushes and no fresh water, which the islanders have to
bring from the mainland. As the Daugo Islanders have no subsistence or cash crops they have
turned to full-time professional fishing and are among the main suppliers of fresh reef fish to
Port Moresby, the capital city of PNG. Lock (1986a, b, c, d) described the Daugo Island reef
fishery where two-thirds of the catches come from surround nets, drive-in nets and gill nets
deployed from outboard-powered dinghies. The balance of the catch comes from hand-lining,
spear fishing and trolling. Unlike the villagers of the Tigak Islands who fish only occasionally,
the fishermen of Daugo Island are active daily, fishing from dawn until mid-afternoon, when
they travel to the produce markets in Port Moresby to sell their catches.
Descriptions of reef fishing for subsistence purposes in the Solomon Islands (Bayliss-Smith
1974, Hviding 1988, Leqata et al. 1990) and Vanuatu (David & Cillauren 1989) are comparable
with those in PNG. Subsistence catches are taken mainly with hand-lines from canoes. Sales of
copra and vegetable produce are among the main sources of income in most locations, rather
than commercial fishing. As with PNG, the most successful commercial reef fishermen are
landless migrants from other provinces who have no alternative incomes from agriculture
(Sasabule 1991). Both New Caledonia and Fiji have large urban populations and well
established commercial reef fisheries, both of which are dominated by landings of emperors,
particularly Lethrinus nebulosus (Dalzell et al. 1992, Anon. 1994a). Commercial reef fish
catches in both countries are taken mainly with hand-lines and gill nets (Loubens 1978a, Anon.
1988b, Rawlinson et al. 1994). New Caledonia and Fiji, in particular, have well developed
tourist industries with over 80000 and 280000 visitors per annum, respectively, that provide an
extra market for commercial reef fish catches.
Subsistence reef and lagoon catches in the rural areas in both New Caledonia and Fiji and are
taken by a combination of spear fishing, hand-lining and net fishing (Leblic & Teulières 1987,
Emery & Winterbottom 1991, Rawlinson et al. 1994, Jennings & Polunin 1995a, b). In Fiji,
around 30% of rural Fijians go fishing at least once a week (37% of the males, 48% of the
females, and 5% of the children, on the main island of Viti Levu), but this involves nearly 100%
of village households (Rawlinson et al. 1994). The main reef fish targeted are species in the
family Lethrinidae, but serranids, hemiramphids, gerreids and scombrids are also prominent,
and carangids are important around the larger islands. Fiji has approximately 2 000 registered
artisanal fishing boats (Anon. 1994b). New Caledonia has a large fleet of recreational craft,
over 11 000 registered vessels mostly berthed in the capital city, Noumea (Fig 2, 71)
(Nguyen-Khoa 1993). According to Loubens (1978a), about 60% of the total catch from the
southwest lagoon of New Caledonia is taken by recreational fishermen, using mainly
hand-lines and spear fishing. Furthermore Kulbicki & Grandperrin (1988) showed that there
was a positive correlation between catch per unit effort (CPUE) of lagoon species and distance
from Noumea in a 50-km radius after which catch rates level off. The 50-km radius is
approximately the outer limit of the range of most recreational fishermen (Loubens 1978a).
As fish, in general, comprise a greater component of the diets of Polynesians and Micronesians,
this demand creates more intensive subsistence and commercial fisheries than in Melanesia. In
Tonga and Western Samoa, nearly 70% of the respective populations are concentrated on one
island in each archipelago, namely Tongatapu and Upolu (Fig 2, 109). Zann et al. (1991) state
that over three-quarters of the villages on Upolu are engaged in fishing with an average of
between two and four fishing trips per week and that half the households in rural areas are
reliant on reef fisheries as the main subsistence source of protein. Almost all fishing occurs in
shallow inshore waters less than 10 m deep, with spear fishing being the most regularly
employed fishing method, followed by net fishing and handlining. Two thirds of the catch is
consumed with the balance being sold in markets in Apia (Fig 2, 4), or increasingly sent by air
to American Samoa, where there is a very high demand for fresh reef fish (Craig et al. 1993).
Tongan reef fisheries have been described by Halapua (1982) and more recently by Tu’avao et
al. (1994). Commercial reef fish catches are made by spear fishing, hand-line fishing, gill and
drive-in netting and from fish corrals. The commercial reef fisheries in Tonga are structured
around small-boat operators who employ a number of fishermen and take the major share of the
catch revenue. Spear fishing and net fishing are conducted on the reefs around Tongatapu;
however, hand-line fishermen have been forced to travel to offshore reefs and banks due to
depletion of stocks around the main island. Fish corrals set on the reef plateau around
Tongatapu were mainly constructed for catching mullet, and were so successful that stocks
declined markedly, leading to a ban (not fully implemented, however) on this type of gear. The
decline in catches has led to a decline in the number of fish corrals around Tongatapu.
Landlessness is also a factor in the commercial reef fishery in Tongatapu. Most of the spear
fishermen in the commercial fishery are migrants from the Ha’apai Islands (Fig 2, 33) who,
possessing no land, turn to a simple and cheap fishing method to provide incomes.
Fishes are one of the very few resources that offer any commercial potential in the Polynesian
and Micronesian atolls, and reef and lagoon fishes are the easiest and most convenient for
fishermen to target. Commercial reef fisheries in French Polynesia supply the main island of
Tahiti where half of the population of this territory now live. About 40 % of the fish sold
through the market in Tahiti are reef fishes from the atolls of the Tuamotu Archipelago (Fig 2,
107). Descriptions of the reef fisheries in these atolls have been given by Grand (1983, 1985),
Grand et al. (1983), Morize (1985) and Caillart (l988a). About 90% of the commercial reef fish
landings in these islands are from fish corrals deployed on the atolls of Kaukura (Fig 2, 38),
Aratua (Fig 2, 5), Tikehau (Fig 2, 100), Rangiroa and Apataki (Fig 2, 3) (Stein 1988). Other
fishing techniques such as gill nets, hand-lines, portable fish traps and spear fishing are used to
supplement commercial catches, when production from the corrals is reduced. Similar
movement of commercial reef fish catches from an outlying atoll to the main urban centre is
also found in the neighbouring Cook Islands. Relatively large volumes of parrotfishes, mullet
and trevallies, caught with gill nets and drive-in nets at Palmerston Atoll (Fig 2, 78), are
regularly sent to markets in Rarotonga (Richards 1993).
Reef fishing in the remoter atolls of Micronesia and Polynesia are entirely for subsistence, apart
from the small amounts of fish that might occasionally be traded with passing ships. Smith &
Dalzell (1993) described reef fishing methods used on Woleai Atoll, one of the outlying atolls
in the Caroline Islands, where many aspects of traditional life are maintained. Reef fishing
methods include hand-lines, spear fishing, portable fish traps and drive in net fishing. While
this is similar to other islands in the Pacific, gears like leaf sweeps used for drive-in-fishing and
fish traps are still manufactured from traditional materials. Furthermore, techniques such as fish
trapping require considerable skill and there are several different trap types deployed in
different seasons to target various reef fish species. Increasing urbanization in atolls, as
elsewhere, is leading to changes in reef fisheries with the development of commercial fisheries
and the adoption of more modern efficient fishing techniques. At Tarawa (Fig. 2, 98), the
principal atoll of Kiribati and home to 40% of the population of the Gilbert Islands (Fig. 2, 30),
the numbers of monofilament hand-lines and gill nets increased exponentially over a 10-year
period to become the most important fishing methods for reef and lagoon fishes (Yeeting &
Wright 1989).
Many of the American associated islands of Micronesia (Palau, Guam, Northern Mariana
Islands, Federated States of Micronesia) are becoming increasingly urbanized as populations
grow and accelerate demand for fresh fish and in particular fresh reef fish. Tourism, mainly
from Japan, is a major industry in islands such as Guam, Palau and Saipan, and is also creating
an additional demand for reef fish. A large range of traditional techniques to catch reef fish have
been documented on Guam (Amesbury et al. 1986) but, as elsewhere, they are largely replaced
with more modern gears. Commercial reef fishing on Guam comprises mainly hand-line fishing
and spear fishing, with minor contributions from various net fishing methods (Myers 1993).
Commercial hand-line fishing targets reef fish stocks in waters < 150 m, mainly emperors
(Lethrinidae), jacks (Carangidae) and snappers (Lutjanidae). Spear fishing consists of two
components based on whether SCUBA equipment is used. Higher proportions of certain
species such as wrasses (Labridae), groupers (Serranidae), parrotfishes (Scaridae) and
goatfishes (Mullidae) are caught by spear fishermen using SCUBA equipment. Commercial
spear fishermen on Guam have driven certain reef species, such as the bump-headed parrotfish
(Bolbometopon muricatum) and the Napoleon wrasse (Cheilinus undulatus), to very low
population levels and similar practices are thought to be depleting populations of the same
species on Palau (Myers 1989, Hensley & Sherwood 1993).
Traditional and contemporary fishing methods for catching reef fish in Palau, include
hand-lining, spear fishing, gill netting, fish trapping and set nets (Johannes 1981). Women and
children on Palau obtain a subsistence catch of fish primarily by hand-lining in reef pools
during the day or spearing fishes from the surface at night (Mathews & Oiterong 1991). No
information is available on the relative contribution to commercial and subsistence catches by
the various gears, although Johannes (1981) states that set nets and spear fishing are the two
most important and productive reef fishing methods employed on Palau. Set nets, known
locally as kesokes, work on the same principle as fish corrals in that they trap fish as they
migrate into deeper water with the falling tide, and concentrate the catch in the apex of a sta-
tionary V-shaped barrier net (Johannes 1981). Besides markets in the capital, Koror (Fig. 2, 41),
reef fishes are also exported to Guam and Saipan, both as official exports and in the form of
passenger luggage on planes. An increasing number of fish buyers are coming to Palau from
Guam and the Northern Mariana Islands to buy fish for sale at home and transporting it in ice
boxes as luggage (Preston 1990a, Adams 1993a), which means that this is not registered in the
official exports from Palau.
Reef fisheries in countries with very limited reef and lagoon areas such as Niue, the Northern
Mariana Islands and Pitcairn Island may still form an important component of total fisheries
landings. In the Northern Mariana Islands, surrounded mainly by narrow fringing reefs and
with limited lagoon area, reef fishes account for half of commercial fish landings. The principle
fishing methods include gill nets, fish fences or corrals, hand-lining and spear fishing (Watt
1990). Nearly all subsistence catches are shallow water reef fishes taken by simila gears. Niue
is a makatea or raised atoll with a narrow coral-encrusted rock shelf. Half of the total fish catch
on Niue comes from fishing on the narrow reef around the island, and about two-thirds of this
catch is taken by hand-line fishing (Dalzell et al. 1993). Commercial fishermen on Niue
concentrate on deep slope and pelagic fish and all reef fish catches are part of the subsistence
production. The small population on Pitcairn Island fish regularly for subsistence and, perhaps
surprisingly for such a remote location, for commercial purposes (P. Sharples, South Pacific
Commission, pers. comm.). Because of historical interest in Pitcairn, however, several vessels
stop by the island each month for the Pitcairners to market fish and carvings. Fishing is
conducted on the fringing reefs and reef slope around Pitcairn Island, either from dinghies or
from the rocky shore. Almost all fishing is conducted with hand-lines targeting the drummer,
Kyphosus bigibbus, and the grouper, Epinephelus fasciatus, for subsistence, while the red
grouper, Variola louti, and the larger eteline snappers on the deep slope are the targets of
commercial fishing.
By contrast, fisheries production on Nauru and Futuna, both islands with narrow fringing reefs
and no lagoon area, is mainly from pelagic rather than reef fisheries. Nauru, like Niue, is a
makatea but it is unusual in that despite its small size it is a very wealthy country, as a result of
substantial revenues generated from mining the phosphate bearing rock that forms most of the
interior of the island. Nauruans fish mainly for recreational purposes from powered skiffs,
trolling for large pelagic species rather than fishing for reef fishes (Dalzell & Debao 1994). The
several thousand Kiribati and Tuvaluan mine workers on Nauru supplement their incomes by
commercial fishing, mainly for large pelagic fishes. A little commercial hand-line fishing for
reef fishes is conducted, however, on the reef slope in waters between 50 to 100 m, often using
a T-shaped or cruciform wire assembly, known as a Christmas Tree, with between 18 and 32
hooks. Small amounts of reef fish are also caught commercially by spear fishing using SCUBA.
In all, reef fishes comprise about 10% of the total fish landings on Nauru. Reef fishes are a1so
caught on Futuna for subsistence, using handlines, spears, and gill nets (Galzin 1985). As on
Nauru reef, however fishes make only a minor contribution (6.0%) to the total fisheries
production on the island, most of which comes from exploitation of large pelagic fishes.
The foregoing summarizes the salient features of reef fisheries in the South Pacific islands. We
will also briefly mention the characteristics of reef fisheries on the Australian Great Barrier
Reef (GBR) (Fig. 2, 29) and around the Hawaiian archipelago. Commercial reef fishing on the
GBR is highly specialized and mainly targets the coral trout, Plectropomus leopardus, and the
emperor, Lethrinus chrysostomus, together with other high value snappers, groupers and
emperors. Catches in both the commercial and recreational fisheries are made with handlines.
Other reef fishes that are highly valued by Pacific islanders such as surgeonfishes, parrotfishes,
rabbitfishes and wrasses are generally not targeted by commercial and recreational fishermen.
The total annual commercial reef fish catch from the GBR amounts to about 3000 t (Brown et
al. 1994). Reef fisheries in Hawaii exhibit more similarities to those in the Pacific islands,
although subsistence catches are not as important and recreational catches form the largest
proportion of the non-commercial catch. Like New Caledonia, Hawaii has a large fleet of
recreational craft, estimated to be 12690 vessels and nearly 190 000 anglers (Smith 1993). Reef
fishes form a relatively small part of the total commercial inshore catch of about 700 tyr-l
(10%) but market preferences increase the value of the reef fishes catch (Smith 1993). Reef
fish are caught predominantly with hand-lines and gill nets by commercial fishermen, while
angling with rod-and-reel assemblies, and spear fishing with and without SCUBA equipment
generate most of the recreational reef fish catch.
The composition of reef fish catches is extremely varied, both in time and location. Table 3
presents information on the composition of reef fish landings from various locations in the
South Pacific classified to the family level. The dominant feature of fish landings in many parts
of the Pacific is the emperors (Lethrinidae), while other important components include
surgeonfishes (Acanthuridae), snappers (Lutjanidae), parrotfishes (Scaridae), and coastal tunas
and mackerels (Scombridae). Although these families contain a large range of species, often
one or a few species will dominate in each family. In New Caledonia and Fiji, for example,
landings of emperors consist mainly of Lethrinus nebulosus (Dalzell et al. 1992, Anon. 1994b),
while in Tikehau Atoll (French Polynesia) emperor landings consist mainly of Lethrinus
miniatus (Caillart 1988a). Similarly, surgeonfish landings in New Caledonia are dominated by
Naso unicornis (Anon. 1992a), while Acanthurus dussumieri and Naso spp. (mainly N.
unicornis and N. brevirostris) constitute most of the surgeonfish landings in the reef fishery on
the South Papuan coast (Lock 1986a). Although commercial reef fish landings in Palau contain
over 200 species, half of the catch comprises only seven species (N. unicornis, Bolbometopon
muricatum, Lutjanus gibbus, Lethrinus ramak, Hipposcarus longiceps, Siganus canaliculatus,
S. lineatus).
Pelagic species such as the small mackerels, Rastrelliger spp., and the large predatory Spanish
mackerel (Scomberomorus commerson) are common components of reef fish landings although
not reef fish sensu stricto. Fishermen trolling along the reef edge often catch large pelagic
predators such as Spanish mackerels, dogtooth tunas (Gymnosarda unicolor), rainbow runners
and queenfish (Scomberoides spp.), which may be included in the reef fish catch. Furthermore,
landings of carangids may be dominated by the small bigeye scads, Selar crumenophthalmus,
and the less common S. boops. These small schooling pelagic fishes are universally prized as a
food fish throughout the Pacific and in some years, when particularly abundant, will dominate
landings of jacks and of reef fishes in general (Helm 1992, Saucerman 1994). A feature of
bigeye scad landings in reef fisheries is their inconsistency, where they can dominate landings
in one year and be virtually absent from the fishery the next (Helm 1992, Hensley & Sherwood
1993, Saucerman 1994).
Catch composition will also depend on the type of fishing gear employed in the fishery.
Hand-lines catch predominantly predatory species such as snappers, groupers and emperors,
but small hooks baited with items such as seaweed, coconut flesh and congealed squid ink can
be used to catch herbivores such as surgeonfishes, rabbitfishes and rudderfishes (Amesbury et
al. 1986). Spear and net fishing tend to take a broader range of species. This is well illustrated
by Table 4, which shows the catch composition for three different methods of net fishing plus
hand-lining and spear fishing on shallow reef stocks of the South Papuan Barrier Reef near Port
Moresby. Two-thirds of the hand-line catch are emperors with most of the balance of the catch
made up from snappers, jacks and groupers. Emperors are also a dominant feature of the net
catches, but there is a wider range of species taken including herbivores such as surgeonfishes,
parrotfishes and rabbitfishes. Spear fishermen rely on getting close to their quarry and emperors
tend to shy away from divers underwater. Other species, such as surgeonfishes, groupers and
scombrids such as Spanish mackerel, that become curious of divers, are vulnerable to spear
There are few long time series of catch species composition data for reef fisheries in the South
Pacific from which to judge the long-term effects of fishing on reef fish communities. Kitalong
& Dalzell (1994) examined a 14-yr time series of commercial reef fish landings data from Palau
and concluded that there had been little change in the compostion of landings over time at the
level of the family. Declines were noted, however, of certain species, such as
Table 3: Percent composition of reef fish catches from various locations in the South Pacific region.
PNG PNG Solomon N. Mariana Kosrae Am. W. Tikehau (Fr. New
Family Fiji (North) (South) Is Kiribati Palau Guam Islands1 (FSM) Samoa Samoa Tonga Polynesia) Nauru Caledonia
Lethrinidae 17.66 10 29 6.2 7.8 14 17.70 1.35 5.36 1.44 19.5 38.36 6 31.02
Chanidae 0.32 2
Balistidae 0.33 2 0.57 0.97 2 4.74
Albulidae 0.01 1 16.5 2
Hemiramphidae 1.66 1
Serranidae 12.62 9 3 6.6 3.1 9 7.58 1.01 5.21 12.84 4.55 4 3.62 18
Scombridae 18.74 3 10 15.3 24.3 1.39 12.57
Carangidae 7.41 14 8 10.2 3.2 4 16.59 1.26 7.88 8.05 1.59 18 3.26
Mullidae 1.48 5 5.1 2.9 1 1.81 0.38 3.56 2.22 8.05 4.56 10 0.77
Lutjanidae 11.01 13 5 192 11.1 12 3.63 0.26 7.36 7.02 1.75 1.33 6 39.54 3.50
Acanthuridae 406 5 7 6.4 14 9.12 1.11 22.73 27.76 19.5 16 20.78 3.65
Scaridae 3.84 8 5 11.5 18 8.48 5.55 6.91 6.33 14 2.69 10 1.17
Belonidae 0.17 5 3.9 0.33 0.02 0.61
Mugilidae 10.24 21 4 3.3 1 0.36 0.04 6.57 7.47 10.45 17.00 6 1.12 10.85
Siganidae 1.08 1 6 3.9 10 5.62 1.80 7.31 0.01 1.05 1.43 2 3.91
Sphyraenidae 7.45 3.2 7.90 0.10 1.07 2 0.24
Gerridae 0.21 2 5.3 0.01 0.07
Haemulidae 1.33 3 4 5.4 0.01
Labridae 4.31 0.03 2.77 0.8 0.16
Holocentridae 5.05 12.47 2.25 4.47 17.26
Theraponidae 0.39 0.03
Others 8 6 6.3 19.3 17 15.99 87.10 22.06 18.62 10.05 26.12 16 6.62 16.51
1. Most reef fish landed in the Northern Mariana Islands are reported only as mixed reef fish.
Table 4: Percent catch composition by different artisanal fishing methods on reef fish
stocks on the South Papuan Barrier Reef.
Fishing method
Family Spear Hand line Gill net Drive-in net Surround net
Carcharhinidae 1 2
Mylobatidae 1
Chanidae 2 1
Hemiramphidae 3
Belonidae 0 1
Serranidae 21 10 3 1
Carangidae 5 7 11 13 4
Lutjanidae 3 12 13 6
Gerridae 0 3
Haemulidae 14 10 5 1
Lethrinidae 1 65 42 31 37
Sparidae 0
Mullidae 3 12
Mugilidae 11
Platacidae 4
Kyphosidae 8 2 1
Sphyraenidae 2 1
Labridae 2 2
Scaridae 3 1 7 10
Acanthuridae 17 2 2 17
Siganidae 0 8 5
Scombridae 17 11 5
Balistidae 3 0 1
Others 3 3 2 6 0
Total 100 100 100 100 100
Crenimugil crenilabis, that were thought to be linked to excessive fishing pressure. Stein
(1988) summarized information from a 25-yr time series of landings of reef fishes from the
Tuamotu Archipelago but, unfortunately, did not comment on whether there have been major
shifts in the catch composition over this time. Catch data between 1982 and 1991 from Guam
were analyzed by Hensley & Sherwood (1993) who showed that there were large declines of
certain species in the reef fish catch such as goatfish (Mulloides flavolineatus), parrotfish
(Bolbometopon muricatum), wrasse (Cheilinus undulatus), and large snappers and groupers.
Catch rates
Catch rates from deployment of artisanal gears such as hand-lines, spears and nets are at best
modest (Tables 4 – 7). Catches from hand-line fishing in shallow water ranged from 0.03 to
12.12 kgline-1h-1 and from 0.44 to 3.5 kgline-1h-1 for overall mean catch rates. In most instances,
the hand-line gear consists of monofilament line equipped with between 1 and 3 hooks, usually
with some form of sinker, although in Nauru, wire rigs bearing between 18 and 32 hooks (see p.
414) are preferred to maximize catches. The principal targets of shallow water hand-line fishing
are groupers, snappers, emperors and jacks. The highest catch rates in Table 5, reported by
Dalzell & Preston (1992), are from fishing mainly on snapper and grouper stocks beyond the
reef margin in waters between 80 and 400 m in depth (see p. 432). Catch rates from underwater
spear fishing ranged from 0.08 to 9.6 kgman-1h-1, with average ranging from 0.4 to 8.5
Table 5: Summary of catch rate (CPUE, catch per unit effort) and catch composition data for hand-line fishing on shallow coral reef and deep-slope
fish stocks in the South Pacific
CPUE (kgline-1h-1) Principal
Location Target stock range mean components Source
Papua New Guinea Shallow reef species 0.68 – 40 2.46 Lutjanidae, Carangidae, Serranidae, Lethrinidae Lock 1986a, c
(Port Moresby)
Papua New Guinea Shallow reef species na 1.2 Lutjanidae, Carangidae, Serranidae, Lethrinidae Wright & Richards 1985
(Tigak Is)
American Samoa Shallow reef species 0.25 – 1.51 0.54 na Saucerman 1994
Guam Shallow reef species 0.03 – 2.04 0.55 Carangidae, Lethrinidae, Acanthuridae, Siganidae Katnik 1982
Palau Shallow reef species 2.2 – 7.32 3.49 Lutjanidae, Lethrinidae, Serranidae Anon. 1992e 1993b
Fiji (Ba Fig. 2, 6) Shallow reef species 0.14 – 12.12 2.27 Lutjanidae, Lethrinidae, Carangidae, Serranidae J. Anderson, MRAG,
London, pers. comm.
FSM (Kosrae) Shallow reef species na 1.78 na Smith 1992a
Tonga (Tongatapu) Shallow reef species na 0.44 Lethrinidae, Holocentridae, Lutjanidae Munro 1990
Tuvalu (Funafuti) Shallow reef species 0.33 – 5.93 2.35 Lutjanidae, Lethrinidae, Serranidae, Carangidae Patiale & Dalzell 1990
Wallis Shallow reef species na 1.3 Lutjanidae, Lethrinidae, Serranidae, Carangidae Taumaia & Cusack 1988
FSM (Pohnpei) Shallow reef and deep 0.69 – 5.12 3.01 Lutjanidae, Carangidae, Serranidae, Lethrinidae Dalzell unpub data
slope species
FSM (Yap) Shallow reef and deep 0.97 – 3.1 1.67 na Uwate 1987
slope species
FSM (Chuuk Outer Banks) Shallow reef and deep 1.31 – 4.57 2.30 Lutjanidae, Carangidae, Lethrinidae, Scombridae Diplock & Dalzell 1991
slope species
Nauru Shallow reef and deep 0.75 – 72 3.0 Lutjanidae, Serranidae, Carangidae, Holocentridae Dalzell & Debao 1994
slope species
Tropical Pacific atolls Deep slope species 0.4 – 19.0 7.7 Lutjanidae, Serranidae, Carangidae, Lethrinidae Dalzell & Preston 1992
Tropical Pacific high islands Deep slope species 2.2 – 13.2 6.0 Lutjanidae. Serranidae, Carangidae, Lethrinidae Dalzell & Preston 1992
Tonga Deep slope species 3.64 – 5.31 45 Lutjanidae, Serranidae, Lethrinidae Mees 1994
Papua New Guinea (Kavieng) Deep slope species 0.6 – 11.24 3.1 Lutjanidae, Serranidae, Lethrinidae Richards & Sundberg 1984
Papua New Guinea Deep slope species na 3.7 Lutjanidae, Serranidae, Carangidae, Lethrinidae Chapau 1988
FSM (Pohnpei) Deep slope species 3.9 – 5.5 4.7 Lutjanidae, Carangidae, Serranidae, Lethrinidae McCoy 1990
Tuvalu Deep slope species 1.72 – 9.62 6.1 Lurjanidae, Serranidae, Carangidae Anon. 1993c
Vanuatu Deep slope species 0 – 5.00 1.44 Lutjanidae, Serranidae, Lethrinidae Schaan et al.1987
Niue Deep slope species 2.1 – 8.5 5.5 Lurjanidae, Serranidae, Carangidae Dalzell et al. 1992
na = not available
Table 6: Summary of catch rates (CPUE, catch per unit effort) and catch composition of
spear-fishing on South Pacific reefs.
CPUE (kgman-1h-1) Principal catch
Location Target stock range mean components Source
Papua New Guinea Reef & lagoon 1.2 – 3.6 2.4 Serranidae, Acanthuridae, Lock 1986a
(Port Moresby) species & large Scombridae, Haemulidae
Papua New Guinea Reef & lagoon na 2.4 Scaridae, Serrallidae, Wright & Richards
(Kavieng) species Lutjanidae, Haemulidae 1985
Palau Reef & lagoon 7.4 – 9.6 8.5 Scaridae, Serranidae, Anon. 1992e,
species Acanthuridae, Lethrinidae 1993b
Nauru Reef and reef 0.2 – 4.3 2.0 Lutjanidae, Holocentridae, Dalzell & Debao 1994
slope species Serranidae, Acanthuridae
Guam Reef & lagoon 0.08 – 1.14 0.41 Scaridae, Kyphosidae, Katnik 1982
species Siganidae, Acanthuridae
Kosrae Reef. & lagoon 18 – 57 3.28 na Smith 1992a
Woleai Reef & lagoon 0.55 – 204 1.27 Acanthuridae, Scaridae Smith & Dalzell
(Micronesia) species Balistidae, Labridae
Tonga Reef & lagoon 1.2 – 1.7 14 Acanthuridae, Scaridae, Halapua 1982
specles Holocentridae, Serranidae
Fiji (Dravuni) Reef & lagoon 0.81 – 1.6 1.20 Serranidae, Acanthuridae, Emery &
species Lutjanidae, Carangidae Winterbottom 1991
Fiji (Ba) Reef & lagoon 0.12 – 5.7 1.51 Lethrinidae, Lutjanidae, J. Anderson, MRAG,
species Serranidae, Scombridae London (pers. comm..)
na = not available
kgman-1h-1. The principal targets for spear fishing are groupers, surgeonfishes, parrotfishes and
snappers (Table 6).
Tables 7 and 8 give details of catches by gill nets, drive-in nets and beach seining in the Pacific
islands. Unlike spear fishing and hand-lining where CPUE is invariably reported as kgman-1h-1
or kgline-1h-1, a range of different units to express CPUE have been used. Comparisons are
further complicated by the variation in net length and mesh sizes employed. Catch per set is the
commonest reported CPUE for gill nets and this ranged from 4.2 to 31.8 kgset-l for the
examples given here. The principal targets for gill net fishing appear to be jacks, mullets,
emperors, goatfishes and snappers. The same problems in the expression of effort and CPUE
were found with the examples of drive-in net fishing in Table 8. Catch rates for drive-in-net
fishing varied between 0.25 and 3.9 kgman-1h-1, or 13.1 and 42.7 kgset-l. The beach seine
catches in Table 8 were all directed towards catching small pelagic fishes in coral reef lagoons,
and all but one of these were taken from the published records of the South Pacific
Commission’s Skipjack Survey and Assessment Programme. The very high average catch rate
for beach seining in Rabaul (Fig. 2, 83), PNG was a result of regular fishing on a large school of
bigeye scads (Selar spp.). Elsewhere, in the Pacific, beach seine catches, predominantly of
small pelagic fishes, tended to be lower, with catches comprising sardines, herrings, goatfishes
and jacks.
Records of catch rates from traditionally manufactured portable fish traps set on reefs in the
South Pacific could not be found in the literature. Available information on performance of fish
traps comes from experimental deployment of Caribbean-style traps on Pacific reefs to catch
species in the shallow reef community or on the deep reef slope to catch mainly large groupers
and snappers. Dalzell (1996) quotes average catch rates of between 0.85 and 4.6 kgtrap-1 for
traps set on shallow reefs and 3.2 to 8.9 kgtrap-1 for traps set on deep reef slopes. Caillart &
Morize (1985) quote average catch rates from fish corrals at Tikehau Atoll during the peak of
Table 7: Summary of catch rate (CPUE, catch per unit effort) and catch composition data for gill net fishing on reef and small pelagic fish stocks in the
South Pacific region
Net length Mesh size CPUE Principal catch
Location (m) (cm) Target stock range mean components Source
American Samoa Reef & lagoon 3.3 – 6.8 kgh-1 5.0 kgh-1 na Saucerman
species 1994
Kiribati na 5.7 – 12.7 Reef & lagoon 5 0 – 96.0 kgtrip-1 43.4 kgtrip-l Albulidae, Carangidae, Anon. 1991c
species Mugilidae, Mullidae
Solomon Islands na 5 – 15 Reef & lagoon 0.26 – 0.90 0.46 kgl00m Sharks, Chanidae, Blaber et al.
species kgl00mnet-lh-l net-1h-l Carangidae, Mugilidae 1990
Cook Islands 90 – 230 4.5 – 5.0 Small pelagics & 0.14 – 18.04 2.2 kg10mnet-1 Carangidae, Priacanthidae, Chapman &
reef fish kg10mnet-1 Mullidae, Caesionidae Cusack 1988d
Fiji (Rabi Island) 150 1.9 – 7.6 Reef & lagoon 15 – 26 kgset-1 189 kgset-1 Lethrinidae, Lutjanidae, Anon. 1983a
species Mugilidae, Holocentridae
Fiji (Rotuma 229 7.6 Reef & lagoon 10.0 – 600 kgset-1 31.8 kgset-1 Mugilidae, Carangidae, Anon. 1983b
Fig. 2, 90) species Lutjanidae, Lethrinidae
Papua New Guinea na 5.0 – 12.7 Reef & lagoon na 2.0 kgman-lh-l Lethrinidae, Lutjanidae, Lock 1986a
(Port Moresby) species Carangidae, Scombridae
Papua New Guinea 35 – 100 3.8 Smll pelagics 0.7 – 6.7 kgset-1 3.0 kgset-1 Carangidae, Clupeidae Dalzell 1993a
Papua New Guinea 100 7.6 – 15.0 Reef & small 0.0 – 17.2 kgset-1 757 kgset-1 Sharks, Scombridae, Chapau &
(Manus) pelagics Chanidae, Clupeidae Lockani 1986
Kosrae (FSM) na na Reef & lagoon 4.2 – 9.1 kgh-l 6.3 kgh-1 na Smith 1992a
Tonga 100 – 1200 5.0 Reef & lagoon 5.6 – 7.2 kgset-1 6.0 kgset-1 Acanthuridae, Labridae, Halapua 1982
species Siganidae. Lethrinidae
Guam na na Reef & lagoon 0 67 – 12.24 kgset-1 4.24 kgset-l Acanthuridae, Mullidae, Karnik 1982
species Scaridae, Labridae
na = not available
Table 8: Summary of catch rate (CPUE, catch per unit effort) and catch composition data for drive-in-net and beach seine fishing on reef and small
pelagic stocks in the South Pacific region.
Net length Mesh size CPUE Principal catch
Location (m) (cm) Target stock range mean components Source
Drive in net
Woleia (Micronesia) 35 4.5 Reef & lagoon 8.1– 129.4 kgset-l 42.7 kgset-l Acanthuridae, Scaridae, Smith &
species Siganidae, Lethrinidae Dalzell 1993
Palau na na Reef and small 2.3 – 1l.1 kgman-lh-1 5.1 kgman-lh-l Carangidae,Lethrinidae, Anon. l993b
pelagic species Acanthuridae, Siganidae
Papua New Guinea na 5.0 – 12.7 Reef & lagoon 1.41 – 4.95 kgman-lh-l 252 kgman-1h-l Lethrinidae,Carangidae, Lock 1986a
(Port Moresby) species Mugilidae, Siganidae
Papua New Guinea 100 6.3 – 7.5 Reef & lagoon na 3.9 kgman-1h-1 Mugilidae,Chanidae, Wright &
(Tigak Is) species Carangidae, Scaridae Richards 1985
Papua New Guinea 100 7.6 Reef.& lagoon 0.45 – 0.74 kgman-lhr-1 0.69 kgman-1h-1 Scaridae, Mugilidae, Chapau &
(Manus) species Carangidae, Acanthuridae Lokani 1986
Cook Islands 14 – 480 2.3 Reef & lagoon 0 – 41 kgset-1 13.1 kgset-l Scaridae Anon 1988a
(Palmerstoll Atoll) species
Nauru na na Reef & lagoon l.1 – 8.0 kghr--l 3.9 kghr--1 Kyphosidae, Mugilidae, Dalzell &
species Acanthuridae, Lutjanidae Debao 1994
Guam 140 – 280 na Reef & lagoon 0.09 – 0.46 kgman-1h-1 0.25 kgman-1h-1 Siganidae, Acanthuridae, Katllik 1982,
species Labridae, Lethrinidae Amesbury et al 1986
Beach seine
Papua New Guinea 200 2.5 Small pelagic na 350 kgset-1 Carangidae, Clupeidae Dalzell 1993a
(Rabaul) species
Papua New Guinea 100 2.5 Small pelagic 1.0 – 44.6 kgset-1 17.3 kgset-l Carangidae Dalzell
(Kavieng) species unpub. data
Butaritari(Kiribati) 80 0.5 Small pelagic 8 – 345 kgset-1 130.6 kgset--l Clupeidae,Atherinidae, Kleiber &
(beach seine) species Apogonidae Kearney 1983
French polynesia 80 0.5 Smal1 pelagic 5 – 33 kgset-1 18.6 kgset-1 Clupeidae, Mullidae, Gillett &
(Marquesas Is) species Carangidae Kearney 1983
Tokelau(Fakaofo 80 0.5 Small pelagic 7.5 – 25.5 kgset-1 13.5 kgset-1 Mugilidae, Clupeidae SSAP 1983a
Atoll) species
Tonga (Vava’u) 80 0.5 Small pelagic 13 – l8 kgset-l 15.0 kgset-1 Atherinidae, Clupeidae, SSAP 1983b
species Mullidae
Marshall Islands 80 0.5 Small pelagic 16 – 38 kgset-1 21.5 kgset-l Clupeidae, Ayherinidae, SSAP 1984
(Majuro & Jalult species Lethrinidae
Atolls (51))
Na = available
the fishing season (November — February) of 380 — 580 kgday-1. Grand (1983) does not give
daily catch rates for fish corrals at Kaukura Atoll but reports that the average fish production
ranged from 1 to 2.3 tcorral-lmonth-l, with a mean of 1.5 tcorral-1month-l
As stated earlier a variety of other methods are used to catch fishes on coral reefs, although
documentation on these is scarce. Average catch rates for cast netting on reefs in Nauru (Dalzell
& Debao 1994), Guam (Katnick 1982) and Kosrae (Smith 1992a) were 0.7 kgman-1h-l, 2.8
kgman-1h-l and 5.6 kgman-1h-l respectively, and comprised rudderfishes (Kyphosidae),
rabbitfishes, surgeonfishes, jacks and goatfishes. Collection of invertebrates and molluscs is a
common pastime on reefs for women and children, and may add significantly to the overall
harvest from the reef (see p. 427). Mathews & Oiterong (1991) made a detailed study of
women’s reef fishing activities and found that they target over 25 species of echinoderms,
molluscs and crustaceans for collection, as well as catching fish with hand-lines and nets. Catch
or harvest rates of all species for gleaners in Kosrae ranged from 2.2 to 4.1 kgh-1, with a mean of
3.6 kgh-l.
Fisheries biology and stock assessment
The biology of reef fishes has received considerable interest in the past 50 yr, due in part to the
development of SCUBA equipment and the ability of biologists to conduct observations in situ.
Sale (1980) provided the first major review of reef fish biology and ecology, and more recently
various contributions in Sale (1991) have provided the most comprehensive review of various
aspects of reef fish biology. Aspects of the biology of South Pacific reef fishes are also covered
by Wright (1993) and Pyle (1993) who, together with Sale, include information on the biology
of reef fishes in the Atlantic and Indian Oceans. Many of the studies on reef fish biology in the
South Pacific have been conducted on the Australian GBR, Hawaii, French Polynesia and
Guam. The focus of much of the research on Pacific reef fishes in the last five decades has been
on small strongly site-associated species, such as damselfishes, with which it is relatively easy
to conduct underwater observations and experiments. However, Munro & Williams (1985)
pointed out in their review of reef fisheries management that there is a general dearth of stock
assessment studies of commonly exploited reef fish populations, either in the South Pacific or
elsewhere, and that there are very few estimates of life history parameters and population
studies such as age, growth, mortality, and recruitment that are essential for stock assessment.
We shall not undertake a detailed biological review in this section, nor in the subsequent
sections on other coastal fisheries resources. We are mainly concerned here with documenting
those studies that have been conducted in the South Pacific on the most commonly exploited
fish and invertebrate stocks, and which have generated information on life histories relevant for
management. From Table 3 (p. 416), the principal reef fish families include the emperors,
surgeonfishes, snappers, jacks, parrotfishes, groupers, mullet, goatfishes, rabbitfishes and
squirrelfishes. As stated earlier, coastal scombrids may form an important component of reef
fish catches, but the biology of these species in the Pacific is reviewed further below (p. 444).
We will also review the methods used to estimate reef fish standing stocks and to compute
maximum sustainable yields (MSYs) from reef fish stocks in the region and compare yields
among the different locations in the Pacific.
The emperors or lethrinids are probably the most widely studied of the Pacific reef fishes that
form major components of reef and lagoon fishery landings. Lethrinids have proved very
amenable to ageing using well established techniques for reading annuli in otoliths and scales,
as well as through more recent techniques for ageing using otolith microstructure (daily
increments) and length based methods. Loubens (1978b, 1980) estimated age and growth of
emperors and a range of other reef fish species from otolith annuli including the economically
important species Lethrinus nebulosus and L. miniatus (= L. chrysostomus). Age and growth of
L. nebulosus from the Australian GBR have also been determined through reading of otolith
annuli (McPherson et al. 1985). Scales (Walker 1975) and otoliths (Brown et al. 1994) have
both been used to age L. miniatus from the GBR and subsequent age-frequency distributions
were used to generate catch curves for mortality estimation. Otolith microstructure or daily
growth increments were also used to estimate the age and growth of L. olivaceus (= L. miniatus)
in French Polynesia (Caillart et al. 1986), L. semicinctus in northern PNG (Mobiha 1993), and
L. rubrioperculatus in American Samoa (Ralston & Williams 1988a). Age, growth and
mortality of exploited stocks of emperors, mainly L. nebulosus, L. mahsena and L. harak, have
been studied in Fiji (Dalzell et al. 1992) using a combination of length based methods and age
estimates from oto1iths. L. harak was also included in a study of commonly exploited reef
stocks in Palau (Kitalong & Dalzell 1994), where growth and mortality estimates were
generated from length-frequency data.
Life spans of the larger Lethrinus species such as L. nebulosus and L. olivaceus would appear to
be in excess of 20 yr, while small species such as L. nematacanthus and L. semicinctus have life
spans of between 7 and 10 yr. Loubens (1978b, 1980) also estimated age and growth from
otolith annuli for the smaller lethrinids or breams in New Caledonia belonging to the genus
Gymnocranius, including G. japonicus, G. lethrinoides and G. rivularus. Age and growth of
another bream, Nemipterus peroni (= furcosus) (Nemipteridae), was also included in Loubens
(1980) study and Chapau (1993) has used otolith annuli and tagging to estimate age, growth
mortality rates and abundance of the same species in populations in northern PNG. Both groups
of breams have average life spans of about 5 — 10 yr.
Surgeonfish biology and life histories have been studied in a number of locations in the South
Pacific, most notably Acanthurus triostegus in Hawaii (Randall 1961), Naso brevirostris in
Tikehau Atoll (French Polynesia) (Caillart 1988b) and Acanthurus nigricauda and A.
xanthopterus in northern PNG (Dalzell 1989). Age and growth of these species have been
described from a combination of observations on captive specimens (A. triostegus), otolith
microstructure (A. nigricauda, Naso brevirostris), length frequency data (Acanthurus
xanthopterus, Naso brevirostris) and tagging (Acanthurus triostegus, A. xanthopterus). Daily
growth increment formation was validated in the otoliths of several juvenile surgeonfishes
including Ctenochaetus binotatus, C. striatus, Zebrasoma scopas and Z. veliferum from the
GBR (Lou & Moltschanowskyj 1992). Otolith microstructure has also been used to provide
preliminary age and growth estimates for Acanthurus lineatus and Ctenochaetus striatus from
American Samoa (Ralston & Williams 1988a). C. striatus has been studied in some detail in
French Polynesia as it is frequently implicated in cases of ciguatera poisoning (Bagnis 1970).
Attempts to estimate growth for this species from tagging data were unsuccessful (Walters
1968, Bagnis 1970) but growth, mortality and recruitment were determined for C. striatus from
Moorea using length-frequency data (Arias-Gonzalez et al. 1993). Similar analyses were also
conducted with length-frequency data for Naso unicornis from Palau (Kitalong & Dalzell
Surgeonfishes appear to have relatively long life spans. Randall (1961) reported adult
surgeonfishes such as Naso unicornis and Acanthurus xanthopterus living for between 15 and
20 yr in captivity. Age and growth studies of A. nigrofuscus populations on the GBR suggest
that this species, one of the smallest acanthurids, has an average maximum life span of over 20
yr (Hart & Russ in press), together with another common species, Ctenochaetus striatus
(N. V. C. Polunin & E. D. Brothers unpub. data). Furthermore, 40 presumptive annuli have
been observed in the otoliths of Acanthurus lineatus from the same location (A. Fowler, Bed-
ford Institute of Oceanography, pers. comm.; Polunin & Brothers unpubl. data). It should be
noted that surgeonfishes on the GBR are subject to virtually no fishing pressure and populations
only experience mortality through natural causes.
Some aspects of the biology of the rabbitfishes or siganids have been studied both in wild
populations and from studies in captive populations in Guam (Tsuda et al. 1976). The species
covered in the various contributions in Tsuda et al. (1976) include Siganus spinus, S. rostratus
and S. argentus. The biology of wild populations of S. lineatus and S. canaliculatus was
observed from wild populations in Palau (Drew 1973), while in Fiji the biology of S.
vermiculatus was described from a combination of observations on wild and captive
populations (Gundermann et al. 1983). Only the growth of juveniles was observed in each of
these various studies, either in captive populations (Tsuda et al. 1976, Gundermann et al. 1983)
or from tagging of juveniles (Drew 1973). The biology of S. canaliculatus in Palau has also
been described by Hasse et al. (1977), while the population biology of this and other rabbitfish
species (S. argentus and S. lineatus) in Palau were described by Kitalong & Dalzell (1994) from
length frequency data.
The biology of shallow water snappers has received less attention than the more commercially
valuable deep slope species. Loubens (1978b, 1980) succecded in ageing in New Caledonia
Lutjanus amabilis, L. bohar, L. fulviflamma, L. kasmira, L. quinquelineatus and L. vitta by
reading otolith annuli. In the same location, Baillon & Kulbicki (1988) have aged the sweetlip,
Diagramma pictum, from otolith and scale annuli and from otolith microstructure.Although not
strictly a snapper, this species belongs to the family Haemulidae, which is closely related to the
Lutjanidae. Wright et al, (1986) described the biology of the red bass, Lutjanus bohar, in
northern PNG and estimated age, growth and mortality parameters from length-frequency data,
Length-frequency data were also used by Kitalong & Dalzell (1994) to generate the same
parameters for L. gibbus in Palau.
Ralston & Williams (1988a) included the small blue-lined snapper, L. kasmira, in studies of
depth distributions, growth and mortality of deep slope fishes in the Northern Mariana Islands.
Age estimates in this study were made from otolith microstructure, whereas mortality rates
were computed from length data, The age and growth of L. kasmira in American Samoa have
also been estimated from otolith microstructure, while Morales-Nin & Ralston (1990) esti-
mated the age and growth of the same species in Hawaii, where it is an introduced exotic, from
both otolith annuli and daily increments, Another small snapper, L. fulvus, from French Poly-
nesia (Caillart et al. 1986) was aged using otolith microstructure, Age and growth of three large
snappers from the Australian GBR, L. sebae, L. malabaricus and L. erythopteru, were
determined from otolith annuli (McPherson & Squire 1992). Although these three species are
not strictly speaking shallow water snappers, they can be found in a greater range of depths than
the eteline snappers, including shallow reef areas. Longevities of between 10 and 20 yr appear
to be typical for Lutjanus spp. and Loubens (1980) reports life spans in excess of 20 yr for even
small species such as L. fulviflamma and L. quinquelineatus.
Parrotfishes, although a common component of reef catches, have received little attention from
fisheries biologists in reef areas. The formation of annular marks in the otoliths of Scarus
schlegeli from the GBR has been validated by Lou (1992), while daily increments in the
otoliths of a range of juvenile parrotfishes, including S. rivulatus, S. globiceps, S. psittacus, S.
sordidus, S. niger, S. frenatus and S. oviceps (all from the GBR) have been observed by Lou &
Moltschaniwskyj (1992) and Lou (1993). Coutures (1994) used annular marks on scales to age
the largest of the parrotfishes, Bolbometopon muricatum, in New Caledonia, and estimated
mortality rates from length-frequency data. Kitalong & Dalzell (1994) also used
length-frequency data to generate growth and mortality parameters for the same species in
Palau. Lou’s (1992) estimates of age and growth of Scarus schlegeli, one of the species in the
middle of the size range of the Scaridae, suggest longevities of between 6 and 9 yr, while
Coutures’ data for Bolbometopon muricatum indicates a life span of about 25 yr. Polunin &
Brothers (unpubl. data) using a combination of scanning electron and light microscopy on
putative annual and finer banding in otoliths, inferred longevities of over 20 yr for Scarus
globiceps, S. sordidus and S. frenatus. The related wrasses or Labridae, appear to have received
even less attention than the parrotfishes. Kitalong & Dalzell (1994) estimated growth and
mortality parameters from length-frequency data for the large Napoleon wrasse, Cheilinus
undulatus, in Palau. Preliminary studies on this species from the GBR suggest that ageing
through reading otolith annuli is practicable and that this species has an expected life span of
about 25 yr (G. McPherson, Northern Fisheries Centre, Cairns, pers. comm.).
Groupers are among the most important of the reef fish landings but little is known about the
biology of species captured in the Pacific islands. The age, growth and mortality of the coral
trout Plectropomus leopardus on the central GBR has been studied by Ferreira & Russ (1992),
while a detailed comparative study of the population biology of P. leopardus from different
locations on the GBR is given by Brown et al. (1994). Earlier estimates of the age and growth of
P. leopurdus were made from length-frequency data (Goeden 1978) but this species like others
on the GBR has otoliths with clear annual markings. Loubens (1978b, 1980) aged P. leopardus
from otolith annuli and included some age-at-length estimates for Epinephelus areolatus, E.
fasciatus, E. hoedti, E. maculatus, E. merra and E. tauvina. Little else has been documented on
the biology of other groupers in the South Pacific. Morize & Caillart (1989) have made some
preliminary investigations of ageing juvenile and adult Epinephelus polyphekiadon (=
microdon) from French Polynesia from otolith microstructure. Their results suggest that the
periodicity of primary growth increments is once every two days rather than daily and that the
rate of increment formation is correlated with growth but not with fish length. Longevities of
groupers in the South Pacific based on the studies reviewed here appear to be typically in excess
of 10 yr.
The biology of other commonly exploited reef fishes in the South Pacific is more fragmentary
with most examples confined to studies in Hawaii, the GBR and French Polynesia. Like the
groupers, jacks (Carangidae) are also a major component of reef fish catches but the biology of
these species does not appear to have been the focus of much attention from fisheries biologists
in the region. The biology of the large jacks, Caranx melampygus and C. ignobilis, in Hawaii
has been studied by Sudekum (1984), who was able to age C. melampygus by primary growth
increments in the otoliths. Also in Hawaii, a study was conducted on the movements,
distribution and growth rates of the goatfish Mulloidichthys flavolineatus by Holland et al.
(1993) using tagging data. Other studies on reef fishes in Hawaii that have generated life history
data related to fisheries management include age and growth from otolith microstructure of the
millet seed butterflyfish, Chaetodon miliaris (Ralston 1976) and of the brick soldierfish
Myripristis amaena, which Dee & Radtke (1989) suggested had a typical life span of 14 yr.
Growth and mortality of another soldierfish Sargocentron microstoma in French Polynesia
have been estimated from length-frequency data by Arias-Gonzalez et al. (1993).
Relatively few estimates of biomass or standing stocks have been made for reef fish
populations in the Pacific islands and these are summarized in Table 9. The majority of esti-
mates are from the Australian GBR and the French territory of New Caledonia. The tech-
Table 9: Estimates of biomass or standing stocks of reef fish on South Pacific coral reefs.
Biomass (tkm-2)
Location Reef type Range mean Method Source
Woleai atoll Atoll lagoon 5 – 25 12 Depletion Smith & Dalzell
(FSM) back reef fishing 1993
Australian GBR Inshore reef 92 Explosives Williams &
Hatcher 1983
Australian GBR Mid-shelf reef 237 Explosives Williams &
Hatcher 1983
Australian GBR Outer shelf 156 Explosives Williams &
Hatcher 1983
Australian GBR Coral island 17.5 – 195 97.5 UVC Goldman &
fringing reef Talbot 1976
Papua New Guinea Fringing reef 43.5 Explosives A. Wright FFA
(New Ireland) pers. comm.
Chesterfield Coral islands 1.7 – 230 105 UVC and Kulbicki et al.
Islands and atolls rotenone 1990
(Fig.2, 15)
New Caledonia Fringing reef 110 UVC Kulbicki 1988
New Caledonia Mid shelf reefs 78 – 96 90 UVC Kulbicki 1988
New Caledonia Barrier reef 92 UVC Kulbicki 1988
New Caledonia Ouvea Atoll 25 – 400 56.2 UVC Kulbicki et al
Enewetak Atoll reef 42.5 UVC Odum & Odum
Hawaii Fringing reefs 0.8 – 237 38.8 UVC Brock 1954
French Polynesia Fringing reefs 140 UVC Galzin 1987
Western Samoa Fringing reef 1l.7 – 74.7 38.7 UVC Samoilys &
slopes and lagoon Carlos 1991a
Fiji Barrier reefs 22.2 – 289 25.1 UVC Samoilys &
Carlos 1992b
a, b. Biomass estimates of Serranidae, Acathuridae, Scaridae, Lethrinidae & Lutjanidae only
UVC = underwater visual census, see text
niques used to estimate standing stocks include underwater visual census (UVC), controlled use
of explosives, poisoning and short-term intensive fishing experiments. UVC techniques
comprise underwater counts of reef fishes, either along a transect line of a given width or in a
given radius from the observer, and estimation of lengths of all individuals for subsequent
conversion of numbers to weight through length-weight equations. As a technique for esti-
mating abundance and biomass of target species, UVC has several limitations, as evident from
the rarity of emperors in extensive counts around reefs of six different fishing grounds in Fiji
(Jennings & Polunin 1995c), whereas these species constitute a major part of the reef catch.
Explosive sampling is based on setting charges where fishes will be killed or stunned within a
known radius and then can be collected by divers following detonation. However, species such
as eels, gobies and blennies in which the swimbladder is poorly developed or absent are not as
susceptible to this method of sampling. The use of poisons involves surrounding patch reefs or
parts of a reef with nets then introducing an ichthyocide such as rotenone on to the reef to kill all
fish within the demarcated area. The objective of such intensive fïshing over a short period of
time is to reduce the standing stock and hence the CPUE where factors such as growth mortality
and recruitment are negligible. The reduction in CPUE can be correlated with cumulative catch
(Leslie’s method) or fishing effort (DeLury’s method) to determine initial biomass or standing
stock within the area being subjected to intensive fishing (Ricker 1975).
From the examples in Table 9, the average standing stock biomass on Pacific reefs ranges from
12 to 237 tkm-2. It is difficult to make any serious comparisons of these figures, given the range
of methods used and the restricted number of locations. The lowest mean figure from Woleai
Atoll was obtained from a series of intensive fishing experiments. Smith & Dalzell (1993) have
suggested that their biomass estimates refer only to that fraction of the total biomass that was
susceptible to the fishing methods employed, namely spear fishing and drive-in net fishing.
Furthermore, the inner reefs of Woleai Atoll are fished regularly by the inhabitants of this
island, who rely on fish as a main source of protein and so the low biomass estimates may also
reflect the removals by fishing. Smith & Dalzell noted that there was an apparent correlation
between biomass on the four reefs in their study and the time interval between the experiments
and the last large-scale community fishing events on these reefs. The other examples in Table 9
are from reefs that are unexploited or were only lightly fished during the period of observations.
The highest figures overall are from the Australian GBR. Here the use of explosives, although
not effective against certain species, permitted sampling throughout the water column and
revealed the large contribution from planktivores, especially fusiliers (Caesionidae), to the reef
fish biomass. Based on the limited data in Table 9 it appears that unexploited or lightly
exploited coastal reefs may typically have standing stocks of reef fishes in the range 50 to 100
As the areas of reef, lagoon and coastal shelf in many locations in the South Pacific and
elsewhere are readily obtainable from nautical charts, aerial photographs and satellite images, it
is often possible to express the catch from reefs in terms of production per unit area. This then
gives an index of exploitation that can be compared with other locations and from which it may
be possible to obtain an indication of the sustainable yield. There are a number of examples
from the South Pacific and elsewhere in the tropics where the amount of fish and/or
invertebrates taken from a given area of reef have been estimated. However, authors have used
a variety of techniques to estimate the fish and invertebrates harvested from a given area, and
they have given different definitions of the area of reef being fished. Some workers have
restricted the definition of reef to include only actively growing hermatypic reef to depths
ranging between 8 and 60 m (see Russ 1991). Some authors have estimated yields based on reef
area and on area of shallow lagoon, which included tidal mangrove areas, seagrass beds and
sand flats. Others have included the reef and the adjacent shelf area to a depth of 200 m in their
estimation of reef yields. These boundary conditions clearly affect the results substantially.
Using a depth limit of 40 m for reef areas and 60 m for other habitats, Jennings & Polunin
(1995a) estimated yield ranges of 0.3 — 10.2 tkm-2yr-l (reef fish/reef area) and 0.2 — 3.4
tkm-2yr-l (reef fish/total area) in six Fijian fishing-grounds (qoliqoli).
The selection of species to be included in harvests creates particular problems when comparing
reef yields between different locations. Catches by reef fishermen may contain substantial
catches of scombrid fishes such as tunas and mackerels (Table 3, p. 416) or snappers, groupers
and other deep slope species caught away from the reef, thus inflating reef yields. Reef yields
may also include the shellfish and other invertebrates collected from the inshore reefs at low
tide. This gleaning activity can in some locations account for a significant fraction of the total
harvest from a reef area, as in Western Samoa where invertebrates account for 36% of the total
reef landings (Wass 1982, Munro 1984), and in Fiji where they account for 72% by weight of
artisanal catches and almost half of subsistence landings (Rawlinson et al. 1994). Despite these
inconsistencies it is still possible to draw some conclusions from the estimates of yield from
Pacific reefs summarized in Table 10. The observed yields are primarily a function of fishing
effort that is itself a function of population density. In the smaller Pacific island countries where
marine produce has always been a primary source of protein, population pressure may lead to
relatively high levels of exploitation on nearshore stocks. Small islands such as Nauru and
Niue, with limited reef and shelf area and extensive fishing activity, have estimated yields of
4.8 tkm-2 (Dalzell & Debao 1994) and 9.3 tkm-2 (Dalzell et al. 1993) respectively from the reef
and shelf areas combined. The highest estimated annual fisheries yields were for fringing reefs
in American Samoa, with a range of 8.6 to 44.0 tkm-2 and a mean of 27 tkm-2.
Table 10: Estimated yields from coral reef fisheries in the South Pacific.
Area fished depth fished Yield
Location Habitat type (km2) (m) (tkm-2yr-l) Source
Papua New Guinea Fringing reefs 207.7 30 0.42 Wright & Richards
Kavieng and patch reefs 1985
Papua New Guinea Barrier and 116 40 5.0 Lock 1986b
Port Moresby fringing reefs
Papua New Guinea Fringing and 61.1 20 2.8 Chapau & Lokani 1986
Manus patch reef
Papua New Guinea (total) All coral reefs 39 940 30 – 60 0.21 Dalzell & Wright 1986
American Samoa Fringing reef 3.0 40 8.6 – 44.0 Wass 1982
Western Samoa Fringing reef 300.0 40 1l.4 Zann et al. 1991
Tarawa (Kiribati) Atoll reef and 459.0 30 7.2 Mees et al. 1988
Ontong Java (Solomon Atoll reef and 122 na 0.6 Bayliss-Smith 1975
Islands) lagoon
Nauru Fringing reef and 7.5 100 4.5 Dalzell & Debao 1994
reef slope
Niue Fringing reef and 6.2 60 9.3 Dalzell et al. 1993
reef slope
Vanuatu Fringing reef and 1063 100 1.9 David & Cillauren
reef slope
Futuna Fringing reef 150 na 0.01 Based on data
in Galzin 1985
Palau Fringing and 450 20 1.7 – 30 Kitalong & Dalzell
barrier reefs
Fiji (Koro (41) & Fringing reefs 8.4 na 5.0 Bayliss-Smith 1975
Lakeba (45))
Fiji (Yanuca (116), Fringing reefs na na 0.3 – 10.2 Jennings & Polunin
Dravuni, Moala (62), 1995a
Totoya (105), Nauluvatu
Ifaluk Atoll (35) Atoll reefs and 5 na 5.1 Stevenson & Marshall
lagoon 1974, based on
observations by Alkire
Locations in Melanesia, where agricultural land is generally more abundant and population
densities much lower, tend to have much lower yields from nearshore fisheries. In PNG the
annual total reef fisheries yield for the whole country was estimated to be 0.21 tkm-2 (Dalzell &
Wright 1986). Based on data presented by David & Cillauren (1989), the total yield of reef
fishes and invertebrates in Vanuatu amounted to only 0.16 tkm-2. Higher annual yields have
been recorded at individual locations in PNG such as Manus (Fig. 2, 54) (3.0 tkm-2) (Chapau
& Lokani 1986) and at the capital city Port Moresby (5.0 tkm2) (Lock 1986c), but these are
still relatively modest when compared with islands in Polynesia and Micronesia. The limited
data suggest that finfish yields in the range 5 to 20 tkm-2yr-1 are probably sustainable in the long
term. If coastal reefs typically have standing stocks in the range 50 to 100 tkm2, then annual
sustainable harvests are likely to represent between 5 and 40% of the standing stock (fishable
teleost biomass), although we acknowledge that this amounts to little more than
speculation given the limits of the present data on standing stocks and yields.
A log book study of six Fijian fishing grounds (qoliqoli) established that at least up to 10.2
tkm-2yr-l (reef fish/reef area up to 40 m depth), yield was linearly related to a rescaled index of
effort (Jennings & Polunin 1995b), indicating that such harvests are sustainable and indeed they
appear to have been maintained for some years in the most fished area (Jennings & Polunin
1995a). Although catch composition varied between grounds, there was no evidence that
less-favoured species were increasing at the more intensely fished sites (Jennings & Polunin
The most comprehensive study of fisheries resources and potential MSY in the region has been
conducted by the French scientific organization ORSTOM in Ouvea Island (Fig. 2, 75)
(Kulbicki et al. 1994), one of the Loyalty Islands archipelago that lie to the east of New Cal-
edonia. From a series of underwater observations and experimental fishing surveys, Kulbicki et
al. (1994) estimated that the total standing stock of reef and lagoon fish was 46500 t of which
l2500 t was found on the reefs. Kulbicki et al. (1994) estimated that the MSY for the fishable
stock might be as high as 4300 tyr-l or about 10% of the total standing stock, but recommended
that a more conservative yield of 1000 tyr-l would be a better management objective. This
would amount to a relative yield of about 1.1 tkm-2yr-1 from the lagoon and reef area combined.
The present volume of landed catch from Ouvea is only 50 tyr-1 or one-twentieth of the
predicted MSY.
Other attempts to estimate MSY for reef fisheries have used modifications of simple surplus
production models, either the simple parabolic form initially developed by Schaefer (1954) or
the exponential modification of Schaefer’s model proposed by Fox (1970). Both forms of the
model are based on the assumption that growth in fish populations conforms to a logistic or
S-shaped curve, with maximum production from a given stock at some intermediate population
density (Ricker 1975). The sustainable yield is the level of fishing effort that takes only the
annual surplus production from the population without depleting the biomass. In the Schaefer
model the relationship between catch and fishing effort conforms to a symmetrical parabola
with MSY when the population is reduced through fishing to half of the unexploited biomass.
The exponential Fox model is an asymmetrical dome shaped curve where MSY occurs when
the population is reduced to about 40% of the unexploited biomass.
Conventional versions of the Schaefer and Fox surplus production models require time series of
catch and effort data to generate MSY and optimum fishing effort. While long time series of
reef fish catch data (15 25 yr) are available for countries such as Palau, French Polynesia and
Fiji, there are no accompanying data on fishing effort due to the multiplicity of gears involved
in the fishery. A shorter, incomplete set of catch and fishing effort data for Tarawa Atoll
(Kiribati) was analyzed by Yeeting & Wright (1989). A direct measure of fishing effort was not
available but an index of effort could be expressed as number of canoes or skiffs, and numbers
of gears such as hand-lines and gill nets. Catch was broadly separated into reef catch, lagoon
catch and ocean catch. Ocean catches were predominantly tunas caught by trolling and, not
surprisingly, mean annual catch rates showed no relationship to annual fishing effort. Mean
annual catch rates from the atoll’s lagoon and reef stocks showed an inverse linear relationship
with effort in gear numbers and in terms of vessel numbers, and catch and effort data could be
fitted with Schaefer curves. The conclusions from this analysis were that the MSY of reef and
lagoon fish stocks in Tarawa Lagoon was about 2800 tyr-l or a yield from the total fished area
(141.8 km2 reef and 330.4 km2 lagoon) of 6 tkm-2yr-l.
Lock (1986bc) fitted a Fox surplus production model using spatial variation in fishing, effort
and catch on a number of different reefs in the Port Moresby-Daugo Island reef fishery over a
1-yr period, to compensate for the lack of a time series of catch and fishing effort data. This
method was adopted from Munro (1983) who developed this technique to estimate the MSY for
the nearshore canoe fishery in Jamaica. Lock’s estimate of MSY for the Port Moresby-Daugo
Island Fishery was 524 tyr-1 or a yield of 7.6 tkm-2yr-l. Munro (1984) also used this approach
with data from Wass (1982) to fit a surplus production model to yield data for finfish and
invertebrates from reefs around Tutuila Island in American Samoa. Although total harvests
from Tutuila (Fig. 2, 108) are not known, Munro concluded that the data indicated an annual
finfish MSY of 20 tkm-2yr and an invertebrate yield of 15 tkm-2yr-l.
Another approach to investigating fisheries yield from coral reefs has been to construct a
trophodynamic model of a reef system. Polovina (1984a) developed an ecosystem box model,
ECOPATH, to estimate the biomass budget of an ecosystem given inputs that specify the
ecosystem components, together with their mortality, diet and energetics value. This approach
was used to model a coral reef ecosystem at French Frigate Shoals in the Northwest Hawaiian
Islands (Polovina 1984b, Atkinson & Grigg 1984, Grigg et al. 1984), and suggested that
fisheries yield might be maximized by harvesting low in the food chain, particularly if top
carnivores can be cropped to release predator pressure on selected prey. One use of
trophodynamic modelling of reef communities has been the indication that fishes around reefs
contain substantial proportions of the total amount of inorganic nutrient elements such as
nitrogen stored within biomass (Polunin 1996). The implication is that in some cases intense
fishing may lead to nutrient-depletion because of the removal of a major reservoir within the
reef system, recovery of which may be slow. The extent to which reef fish productivity may
depend on nutrient inputs, however, is unknown. The opportunity to examine changes in
biomass and turnover of reef fish stocks in nutrient-poor and upwelling-enriched regions
offered by the Pacific has apparently not been explored. The potential role of planktonic inputs
in the production of groupers, snappers and other important reef predators is being explored,
however, by using carbon, nitrogen and sulphur stable isotopes (N. V. C. Polunin unpubl. data).
Socioeconomic developments
Shallow water reef fisheries, like most coastal fisheries in the Pacific, remain the preserve of
small-scale artisanal fishermen. Even in the commercial sectors of most countries, the gears
employed are largely non-mechanized, and in the Pacific, most reef fish catches are generated
from hand-lines, spears, gill nets or drive-in nets. The only exception has been the proliferation
of fish corrals in the Tuamotu Archipelago of French Polynesia, where these gears are used to
catch large volumes of reef fishes to satisfy the demand for fish on Tahiti, the principal island in
the territory. Elsewhere, fishermen have sought to improve catches through the greater use of
modern fishing gears such as monofilament lines and nets, diving equipment and more reliance
on outboard motors to range over wider areas. Governments have sought to encourage greater
fisheries production from reef and other coastal fisheries by providing better facilities for
fishermen to dispose of catches and in some instances provision of easy credit or “soft” loans to
buy vessels and equipment.
In the past, most catches from nearshore reef fisheries were consumed at or close to the landing
site but, as indicated earlier, there was a greater dispersai of landings from their point of origin
to other domestic and international markets as national economies developed and urbanisation
increased. Besides the examples given earlier for French Polynesia, Cook Islands and Western
Samoa, reef fishes are now exported from Kiribati to Hawaii and Nauru, from Solomon Islands
to Japan, and from Fiji to Tonga and New Zealand. A trend in the western part of the region is
the development of live reef fish fisheries for the restaurant trade in Southeast Asia. Reef fishes,
such as coral trout, other groupers and Napoleon wrasse, are caught around the coast of PNG
and shipped live by air and sea to markets in Hong Kong, mainly for the restaurant trade,
although there is also a demand for live stonefish (Synanceia verrucosa and S. horrida) for
traditional Asian medicines as well as for food (Richards 1993). A similar type of operation was
conducted from Palau to Hong Kong before concern over levels of fishing pressure forced the
closure of the fishery (Johannes 1991). Interest has also been shown in developing live reef fish
exports from Tuvalu (I. Keay, Tuvalu Fisheries Division, pers. comm.) and from the Australian
GBR (A. H. Richards, Forum Fisheries Agency, pers. comm.) and Richards (1993) has
suggested that as reef fish resources are increasingly depleted in the South China Sea region,
companies based in Taiwan, Hong Kong and Singapore will venture increasingly into the South
Pacific in search of groupers and Napoleon wrasse.
There is also growing interest in the Pacific islands in developing export fisheries for the
international aquarium fish trade. Aquarium fish fisheries are operating in Fiji, the Cook Is-
lands, Vanuatu, Palau, Kiribati, Tonga and the Marshall Islands. The common target species of
aquarium fish fisheries are the smaller reef species not normally targeted heavily for food. Pyle
(1993) lists 10 families (Pomacanthidae, Chaetodontidae, Acanthuridae, Labridae, Serranidae,
Pomacentridae, Balistidae, Cirrhitidae, Gobiidae and Blenniidae) as the most important to the
aquarium trade. Over 240 species of reef fish are listed in the export figures reported from Palau
(Anon 1993b), with the most common being the damselfishes (Pomacentridae), Chrysiptera
cyanea, Chromis albipectoralis and Dascyllus aruanus, which are of little unit value, price
range US$0.2 – 0.3 per fish. However, this is much higher than the price received for reef fishes
sold for food and comparatively rare specimens such as Ctenochaetus tomiensis may be worth
as much as US$25 per fish.
Improvements in fishing power of gear and growth of human populations have in many
locations been paralleled by declines in stocks, catch rates and, in some cases, landed volume of
reef fishes. Certain species may be extremely vulnerable to particular fishing gears. As stated
earlier, the combination of spear fishing and SCUBA gear is believed to responsible for the
extinction of Bolbometopon muricatum and Cheilinus undulatus at Guam and the large-scale
population decline of these species on Palau. Other cases of finfish stock depletion have been
reported in the Pacific. These include declines in reef and lagoon fish stocks in Palau (Johannes
1981, 1991), reef fishes and lagoon fishes in Kiribati (Yeeting & Wright 1989), bonefishes,
milkfishes and parrotfishes in the Cook Islands (Anon. 1988a, J. Dashwood, SPC Fisheries
Programme, pers. comm.), various grouper stocks in French Polynesia (Bell 1980), Tokelau (
Hooper 1985) and the Cook Islands (Sims 1990), and reef and small pelagic fïshes in Western
Samoa (Helm 1992).
In many locations in the Pacific, exploitation of reef resources is regulated by communities,
particularly via traditional concepts of marine tenure (see contributions in Ruddle & Johannes
1985 and South et al. 1994). In some locations, customary ownership of fishery resources has
almost disappeared, resulting in open access to nearshore reef resources. Fisheries management
and development must account for traditional ownership where it exists, and this may be
formalized in legislation as in Fiji (Adams 1993c, Adams 1996). Contemporary approaches to
managing reef fisheries in some locations in the region may include very detailed fisheries
regulations and ordinances that specify closed seasons, areas closed to fishing, size limits for
certain species and mesh size limits for fishing gear. Such approaches are likely to be more
enforceable in the commercial sector than at the community or village level.
Apparently, the only objective attempt to assess the robustness of traditional management in the
face of resource pressure has been that of A. Cooke and N. V. C. Polunin (unpulbl; see also
Cooke (1994) and Cooke & Moce (1995). An index of “management aptitude” was derived
from the responses of eight Fijian qoliqoli managers to a set of specific questions including
queries as to their use of information for management, approach to goodwill payments, work
with the Fisheries Division and management and enforcement measures taken. Of four qoliqoli
subject to high commercial fishing pressure, two showed high aptitude and two low aptitude.
Among the qoliqoli studied, those with highest aptitude showed, in particular, evidence for
liaison and collaboration with the Fisheries Division. The inference was that those exhibiting
low aptitude might benefit from some form of co-management with the Fisheries Division.
Coastal reef finfish catches will continue to be the main source of subsistence protein for most
Pacific island countries for the foreseeable future, but there is likely to be an increasing volume
of high value species being transported to domestic urban and tourist centres and exported to
overseas markets. Problems are likely to occur in countries where yields from coral reef
fisheries cannot keep pace with population growth and where there are no major developments
in targeting offshore fish stocks or aquaculture. Those islands most at risk from this
“Malthusian overfishing” (as defined by Pauly 1990) of reef fish will be those with a high
human population in comparison with the available reef and lagoon area. There is not yet any
comprehensive quantification of coastal fisheries habitat are as for the Pacific islands, so this
ranking cannot yet be made, but islands such as Saipan, Upolu, Rarotonga and Tarawa, for
example, would definitely appear to be in a high-risk category.
Deep-slope fisheries
Beyond shallow reef slopes, in depths where hermatypic corals do not flourish, lie the deep reef
slopes. These are usually areas of sand and coral boulders, but with other sediments also present
depending on island type and proximity to rivers and alluvial deposition. The deep reef slope
typically starts at about 80 m and extends to about 400 m depending on the steepness of the
island shelf. The fish community of the deep reef slope is simpler than the neighbouring
shallow reef and comprises mainly large carnivorous species of snappers (Lutjanidae), groupers
(Serranidae), emperors (Lethrinidae) and jacks (Carangidae). Catches of snappers from the
deep reef slope are dominated by members of the genera Pristipomoides and Etelis (referred to
here collectively as eteline snappers) that are high quality fish with a high demand from
overseas markets in Japan and Hawaii. These deep-slope fish stocks have, until recently, been
lightly exploited or unexploited throughout most of the South Pacific region. Exceptions are the
limited subsistence fisheries for deep-slope snappers and oil fish (Ruvettus pretiosus) at some
Polynesian atolls (Wankowski 1979) and in Hawaii where deep-slope fish stocks have been
continuously exploited for over 50 yr (Ralston & Polovina 1982, Polovina 1987, Shomura
During the early 1970s, the South Pacific Commission commenced surveying the deep reef
slope stocks of the Pacific islands and demonstrating techniques useful for exploiting these
stocks (Dalzell & Preston 1992). Initial surveys in Polynesia and Melanesia revealed the
existence of fishable stocks but the techniques used were not appropriate for the Pacific
islands. From 1979 onwards the Commission propagated the use of more appropriate fishing
technology, based around small diesel-powered dories and manual fishing reels first developed
in Western Samoa (Gulbrandsen 1977). The efforts of the Commission and its extension
programme led to the establishment of deep-slope fisheries in many locations in the South
Pacific, including Tonga, Fiji, Vanuatu, American Samoa, Western Samoa, Solomon Islands,
PNG, Federated States of Micronesia and French Polynesia.
Not all of these fisheries have persisted and the reasons why they have failed in various
locations are a mixture of both stock depletion and socioeconomic factors. The most successful
deep-slope fishery is probably the fishery in Tonga, which began on the nearshore slopes of the
archipelago but graduated to the numerous seamounts in the Tongan EEZ from which most of
the Tongan deep-slope catch now originates. The deep-slope fishing fleet is composed of
wooden dories between 6 and 11 m in length, powered by 20 hp Yanmar diesel engines. The
boats were constructed locally with credit supplied from two United Nations agencies. All
boats use between four and five wooden hand-reels, most commonly baited with the
commercial long-line bait of saury (Cololabis saira).
Descriptions of the Tongan fishery are given by Langi & Langi (1987) and Latu & Tulua
(1991). The dories make voyages lasting 5 days, of which 2 days are traveling time and three
days are spent fishing on seamounts. On average between three and four reels are deployed
during a fishing trip for a period of about 7 h per day. Each vessel completes about 30 fishing
trips per year. Most of the dories are based in Tongatapu, with a small number of boats landing
fish into Vava’u. The fishermen sell their catch to fish buyers, some of whom also own fishing
vessels. About two-thirds of the catch is sold locally, while the prime species Etelis coruscans
and Pristopomoides filamentosus are air freighted to markets in Hawaii. Initially, about 40
dories were operating in the fishery, but the fleet has now shrunk to between 15 and 20 vessels:
some boats have been used for other purposes such as bêche-demer collection or simply were
no longer seaworthy Annuallandings from the Tongan deepslope fishery amount to between
210 and 514 tyr-1 with current production at around 250 tyr-1.
The deep-slope fishery in Fiji has not been as well documented as the Tongan fishery but was
nearly as large during the mid 1980s in terms of production volume. Furthermore, the Fiji
fishery was innovative in the use of larger more sophisticated fishing vessels, using commercial
fish-finding sonars and deploying bottom long-lines and hydraulically operated reels rather
than the simple wooden hand-reel. The Fijian fishery was also the first in the South Pacific to
explore the possibility of exporting fish to more lucrative overseas markets. Lewis et al.
(1988b) provide the best description of the Fiji deep-slope fishery prior to its demise after 1987.
The Fiji deep-slope fleet comprised one 20 m Hawaiian long-liner, four larger local vessels
(three drop-line and one long-line) and a number of 9 m dories, similar to those used in Tonga.
The larger vessels deploying hydraulic reels used lines with five or more hooks per line. Bait
used throughout the fishery was skipjack rejected by the local cannery. The larger vessels used
a palu, or chum bag, to aggregate fish and increase catch rates. At the peak of the Fiji fishery
about 200 t of deep-slope fishes were landed annually, with about 75% of this sold overseas.
Disruption in airline scheduling following political events in 1987 was a serious setback to the
fishery, where profit margins were not large. However, the vessels involved in the fishery
began to shift from demersal fishing to pelagic long-lining to catch large high-value tunas such
as yellowfin (Thunnus albacares) and bigeye (T. obesus). These species can be caught more
reliably than deep-slope fishes, realize a much better return on overseas markets and stocks are
not nearly as limited as stocks on the deep slope. The expansion of the deep-slope fishery in Fiji
was based largely on catches from unexploited stocks, where catch rates could fall by one order
of magnitude in a short period of time, particularly when fishing on seamounts.
The Vanuatu deep-slope fishery was based on the Village Fisheries Development Plan (VFDP)
that was conceived as a strategy to increase the supply of fresh fish from village based fisheries
in the country. As part of the overall plan, locally built wooden dinghies and catamarans were
equipped with the Samoan hand-reel and various incentives were offered to village groups to
become involved in the fishery, such as duty-free gasoline. In recognition of the fact that
Vanuatu villagers were not used to fishing outside the shallow reef zone, a training centre was
established in Luganville (Fig. 2, 125), to impart the skills required to become an artisanal
fishermen targeting deep slope fishes. The fishery expanded from just six boats in 1982 to 180
by 1988, although not all boats were engaged in full-time fishing. Descriptions of the
deep-slope fishery in Vanuatu are given by Schaan et al. (1987) and Carlot & Nguyen (1989).
The volume of landings in the Vanuatu fishery between 1982 and 1988 ranged from 10 to 86
tyr-l with a mean of 50 tyr-1, while a survey of commercial fisheries in Vanuatu during 1992
suggested an annual production from the deep-slope fishery of about 80 t (Anon. 1992b).
Dalzell (1992a) noted that in response to declines in catch of deep-slope fishes, Vanuatu
fishermen were now targeting shallow reef species. Although the VFDP was planned to
increase fish supply for the village population, much of the deepslope catch is now sold to the
restaurant and hotel trade in Port Vila (Fig. 2, 81) and Luganville.
PNG has by far the largest resource of deep-slope species in the South Pacific but only one
commercial fishery, on the north coast of the mainland, was ever successfully established there.
The fishery landed between 5 and 20 tyr-1 between 1983 and 1985, before going into decline
after government support for the fishery was reduced (Chapau & Dalzell 1991). A combination
of factors contributed to the decline of the American Samoan fishery, which was comparable in
scale to the fishery in northern PNG, but where landings were exported to Hawaii to realize
greater profits. Among the factors responsible for the decline in the fishery were a fall in catch
rates of deep-slope stocks, volatility of the prices on the Hawaiian market, delays in payment
for export catches and competition from purse-seine by-catch on the domestic market (Itano
Elsewhere in the South Pacific, small amounts of deep-slope fishes are caught for local
markets. Landings of deep-slope fishes in French Polynesia are mainly from recreational
fishermen and landings range from 0.5 to 10 t annually (Wrobel 1988). Between 40 and 80 t of
deep-slope fishes are landed annually in New Caledonia for domestic consumption (Anon
1994a). Recently, a commercial survey of seamounts and banks in the Tuvalu EEZ has led to
catches of deep-slope fishes, some of which have been marketed in Hawaii (Anon 1993c).
Small amounts of deep-slope fishes have been caught and air-freighted to Japan and Hawaii
from the Federated States of Micronesia, but production has not been consistent (P. Dalzell
unpub. data).
Catch composition
By contrast to shallow reef fish fisheries, which have been largely ignored by fisheries scien-
tists in the South Pacific, deep-slope species have been the focus of a considerable amount of
research and monitoring. Dalzell & Preston (1992) present the most coherent data set on
composition of deep-slope fishery catches throughout the Pacific. These data (Table 11) are
based on surveys conducted by the South Pacific Commission on what are essentially
unexploited stocks. Nearly all the Pacific islands are included in this data set, notable excep-
tions being Guam, Nauru and Pitcairn. The snappers, or Lutjanidae, are divided into two
groups, following the taxonomy proposed by Johnson (1980); the subfamilies Etelinae and
Apsilinae, or deep-slope snappers, and the subfamilies Lutjaninae and Paradichthyinae, or
shallow water snappers.
The Lutjaninae are more a feature of shallow lagoon habitats but species such as Lutjanus
bohar and L. argentimaculatus migrate down the deep reef slope as they increase in size
(Wright et al. 1986). Indeed, of the total number of fishes caught in the Commission surveys, L.
bohar was the commonest species (4.6%), followed by Caranx lugubris, Pristipomoides
filamentosus, Etelis carbunculus and Pristipomoides flavipinnis that together formed over 20%
of the total catch. A further eight snapper species (Pristipomoides zonatus, P. multidens, P.
auricilla, Etelis radiosus, E. cornscans, Lutjanus gibbus and Aphareus rutilans), formed a
further 20% of the total.
Factors such as position or longitude, average depth fished, seasonality, island type and size and
fishing intensity will have an effect on the composition of catches. Dalzell & Preston (1992)
compared species composition between catches at high islands and catches around atolls. They
showed that catches from high islands contain a significantly greater amount of the
commercially valuable eteline snappers than at atoll sites. Furthermore, catches at atoll sites
contained greater numbers of sharks, which have little or no commercial value. Regional
differences also exist between the species composition of deep-slope catches from the Pacific
islands. We have summarized data on catches from the South Pacific Commission’s surveys
Table 11: Percent composition of deep-slope catches from different locations in the South
Country/ Lutjaninae Serranidae Carangidae/ Gempy- Sphyrae- Other
Territory Etelinae Lethrinidae Scombridae lidae nidae teleosts Sharks
American 42.4 18.1 14.9 2.1 12.4 0.7 8.9 0.8 0.0
Belau 36.0 11.8 4.1 12.4 15.2 7.0 1.7 3.5 5.2
Cook Islands 50.7 2.0 1.2 9.4 9.9 4.7 0.1 6.7 15.2
Federated 21.7 18.6 4.4 7.4 18.5 2.4 1.0 4.9 21.2
States of
Fiji 24.6 11.9 5.4 8.1 15.1 2.7 5.2 1.5 25.6
French 28.7 2.5 0.2 30.2 19.7 14.1 0.1 1.6 3.0
Kiribati 13.5 32.8 3.4 21.6 5.5 5.4 0.4 0.7 17.1
Marshall 8.5 14.3 6.5 10.1 8.1 1.1 0.3 2.3 48.9
New Caledonia 24.4 9.6 19.4 11.4 56 0.0 2.8 0.2 25.3
Niue 10.1 27.2 11.2 13.5 9.2 3.9 1.2 15.3 3.3
Northern 60.3 0.0 0.1 0.5 34,4 0.0 0.0 0.0 0.0
Papua New 49.2 16.1 3.8 7.2 7.0 0.5 0.9 0.4 153
Solomon 61,0 14.3 0.4 10.8 1.9 0.0 7.8 3.8 0.0
Tokelau 21.8 2.9 6.1 6.9 27.9 5.5 1.5 2.3 25.4
Tonga 49,0 3.9 20.2 13.8 5.5 0.8 1.1 0.5 5.0
Tuvalu 17.1 10.2 0.9 10.1 12.6 32.8 0.7 0.5 15.2
Vanuatu 45.5 10.6 2.1 19.1 3.9 4.6 0.2 1.3 12.9
Wallis & 56.8 4.6 5.8 12.2 1l.6 0.0 0.1 0.3 8.8
Western 45.9 7.1 1.2 5.6 5.0 25.0 0.0 3.8 65
Table 12: Composition by species of three families taken by deep-slope hand-line fishing
in the South Pacific region.
Percentage composition by sub-region
Family and species Melanesia Micronesia Polynesia
Aphareusfurca 0.05 0.82 0.90
A. rutilans 7.98 6.27 8.34
Aprion virescens 1.49 4.41 6.49
Etelis carbunculus 6.76 20.56 9.47
E. coruscans 4.71 15.02 5.53
E. radiosus 2.79 0.20 0.89
Pristipomoides kuskarii 3.13 2.91 0.00
P. amoenus 1.20 0.52 0.21
P. auricilla 1.59 5.82 27.63
P. filamentosus 23.41 10.83 10.84
P. flavipinnis 18.61 9.32 4.80
P. multidens 22.99 1.11 0.98
P. zonatus 2.80 17.29 18.19
Others 2.50 4.92 5.73
Lutjanus argentimaculatus 8.76 18.08 2.65
L. bohar 22.59 43.38 33.18
L. gibbus 11.85 29.66 15.20
L. kasmira 2.16 1.85 32.06
L. malabaricus 18.86 0.25 0.22
L. monostigma 8.64 0.95 0.49
L. rufolineatus 2.04 4.38 1.57
Others 25.10 1.44 14.62
Gymnocranius japonicus 5.23 0.30 0.82
Lethrinus chrysostomus 11.80 0.89 53.18
L. kallopterus 0.81 5.33 4.00
L. miniatus 15.90 32.99 17.01
L. reticulatus 0.15 3.11 0.00
L. variegatus 1.76 11.09 5.94
Wattsia mossambica 52.09 27.51 7.99
Others 12.27 18.79 11.07
Cephalopholis aurantia 0.25 1.25 2.32
Epinephelus areolatus 4.39 8.26 4.01
E. chlorostigma 7.05 2.35 0.23
E. cometae 8.13 0.16 0.41
E. fasciatus 0.00 0.55 1.82
E. jlavocaeruleus 1.53 1.76 0.27
E. magniscutis 0.49 0.63 0.00
E. miliaris 3.79 18.23 9.43
E. morrhua 27.35 14.44 12.48
E. retouti 1.13 0.47 10.02
E. septemfaciatus 4.73 0.08 5.15
Saloptia powelli 0.89 0.16 5.60
Variola louti 7.24 8.10 11.75
Others 33.02 43.58 3649
presented by Dalzell & Preston to highlight differences between four common components of
deep slope catches, namely eteline snappers, lutjanine snappers, emperors and groupers, with
respect to the three archipelagic groupings of Melanesia, Micronesia and Polynesia (Table 12).
This effectively splits the Pacific into the small high islands and atolls north of the equator
(Micronesia), the large high islands in the west of the Pacific and south of the equator
(Melanesia) and the small high islands and atolls of the central Pacific that lie to the south of the
equator (Polynesia).
In the small high islands and atolls of Micronesia, north of the equator, deep-slope catches of
eteline snappers are dominated by Pristipomoides auricilla and P. zonatus. In similar habitats
in the central and southern Pacific P. zonatus is also a major component in deep-slope catches
along with Etelis carbunculus and Pristipomoides filamentosus. Catches on the slopes of the
large Melanesian islands are dominated by P. multidens and to a lesser extent by P.
filamentosus. As with the etelines, there are subregional differences in the lutjanine snapper
composition from deep-slope hand-lining. In the Polynesian islands the small blue-line
snapper, Lutjanus kasmira, and the red bass, L. bohar, each form about one third of the
lutjanine snapper catch, with the other major contribution being from L. gibbus. In similar
habitats in Micronesia, L. bohar is the dominant lutjanine snapper, along with L. gibbus and L.
argentimaculatus. On the larger slope areas of the Melanesian islands, L. bohar, L.
argentimaculatus and L. gibbus are still dominant features of the snapper catch but dominance
is shared with L. malabaricus.
Over half of the catch of emperors from the deep slopes around the large Melanesian islands
comprises the deep-slope bream, Wattsia mossambica. Other dominant emperors included
large and readily identifiable Lethrinus olivaceus (= miniatus) and L. miniatus (=
chrysostomus). L. olivaceus and Wattsia mossambica were also dominant features of the
emperor catch from Micronesian islands along with Lethrinus kallopterus and L. variegatus.
The dominant feature in the catch from Polynesian islands was L. miniatus followed by L.
olivaceus. Wattsia mossambica formed only a small portion of the lethrinid catches around
Polynesian islands.
The proliferation of species in the family Serranidae and the difficulties in identifying species,
particularly in the field, are reflected in the relatively large percentages in the other species
category (Table 12). However, grouper catches from the Pacific islands tend to be formed
mainly from the following species: Epinephelus morrhua, E. miliaris, E. retouti and Variola
louti. In Melanesia, Epinephelus morrhua was clearly the dominant grouper species in
deep-slope catches, while in Micronesia dominance was shared between E. miliaris and E.
morrhua, and in Polynesia, among E. morrhua, E. miliaris and E. retouti. The coral cod Variola
louti was common to grouper catches in all three locations, while Epinephelus cometae and E.
chlorostigma were dominant features of catches in Melanesian waters, and E. areolatus of
catches from Micronesia. Another feature of deep-slope catches from Melanesian and
Polynesian islands, particularly from unexploited fishing grounds is the giant grouper E.
septemfasciatus. This species is among the first to be fished out in deep-slope fisheries where
effort is particularly heavy.
Brouard & Grandperrin (1985) classified catches of deep-slope catches in Vanuatu according to
depth. Shallow species were defined as those in waters < 120 m and included many species
commonly found on coral reefs such as squirrelfishes, small groupers, emperors and snappers.
Species in waters of intermediate depths (120 — 240 m) consisted mainly of eteline snappers of
the genera Pristipomoides and Paracaesio, and the larger emperors, lutjanine snappers and
groupers. Deep water species (> 240 m) included the three Etelis species, large groupers such as
Epinephelus septemfasciatus, hexanchid sharks and oil fish (Ruvettus pretiosus). Sundberg
& Richards (1984) arranged the 10 most common species in deep-slope (80 — 300 m) catches
from northern PNG from common to less common as follows: Lutjanus bohar, Lethrinus
miniatus, Lutjanus erythropterus, Aphareus rutilans, Lutjanus malabaricus, L.
argentimaculatus, Wattsia mossambica, Pristipomoides multidens, Etelis coruscans and E.
Catch rates
The most comprehensive summary of catch rates from fishing on Pacific island deep-slope
stocks is given in Dalzell & Preston (1992). It should be noted, however, that these catch rates
are for mainly unexploited stocks and do not apply to commercial fishing. Catch rates ranged
from 0.5 — 19.0 kgline-1h-l with a mean of 7.0 kgline-lh-l. These gross catch rates include
sharks, which are sometimes discarded and not recorded in catches. Catch rates for teleost fish
only ranged from 0.3 — 14.5 kgline-1h-l, with a mean of 6.6 kgline-1h-l. Average catch rates
around high islands and atolls were 5.5 and 6.8 kgline-1h-l respectively but there were no
significant differences between these means.
Average catch rates in commercial fisheries and survey fisheries in the South Pacific are also
included in Table 5 (p. 418). Catch rates in the Tonga deep slope fishery ranged from 2.76 —
13.3 kgline-1h-l with an overall mean of 6.4 kgline-1h-l for the years 1986 — 92 (Mees 1994).
Sustained fishing on deep-slope stocks over a period of 1 yr in northern PNG by Richards &
Sundberg (1984) produced catch rates ranging from 0.6 to 11.24 kgline-1h-l, with a mean of 3.1
kgline-1h-l. Similarly, Chapau (1988) reported an average catch rate of 3.7 kgline-1h-l in the
small commercial deep-slope fishery based near Wewak (Fig. 2, 114) in northern PNG between
1983 and 1985. A similar small-scale operation fishing around Pohnpei (Federated States of
Micronesia) and the nearby atolls of Ant and Pakin (Fig. 2, 2) between 1983 and 1986 produced
catch rates that ranged from 3.9 to 5.5 kgline-1h-l with a mean of 4.7 kgline-1h-l (McCoy 1990).
A small-scale pilot commercial fishery operating around Pohnpei in 1989 experienced catch
rates of 0.7 — 5.1 kgline-1h-l with a mean of 3.0 kgline-1h-l (P. Dalzell unpub. data). Survey
fishing of banks and seamounts around Tuvalu during 1992 and 1993 experienced catch rates
ranging between 1.72 and 9.62 kgline-1h-l with an overall mean of 6.1 kgline-1h-l (Anon. 1993c).
Catch rates experienced by village fishermen fishing on deep-slope stocks in Vanuatu in the
mid 1980s ranged from 0 to 5.00 kgline-1h-l with a mean of 1.44 kgline-1h-l. Average monthly
catch rates for hand-line fishing on the Chuuk Outer Banks (Fig. 2, 17) ranged from
1.3 — 4.57 kgline-1h-l with a mean of 2.30 kgline-1h-l. Catches comprised both deep-slope and
shallow water reef fishes. Sustained commercial fishing on the deep-slope stocks of Niue
between 1988 and 1990 generated average monthly catch rates ranging between 2.1 and 8.5
kgline-1h-l, with an overall mean of 5.5 kgline-1h-l.
Less information is available on catch rates from long-line fishing on deep-slope stocks and
most of the fishing refers to surveys of virgin stocks. The limited information available has
been summarised in Table 13. Average catch rates ranged from a low of 6.8 kg100hooks-1 on
the Chuuk Outer Banks to a high of 124 kgl00hooks-1 on the shelf area off the south coast of
Espiritu Santo (Fig. 2, 22) in Vanuatu. The catch data from Fiji are from a commercial fishing
operation that fished on the outer banks and sea mounts in Fiji’s EEZ and are probably more
indicative of the returns from this method of fishing on deep-slope fish. Also included in Table
13 is a summary of long-line fishing in the lagoon of New Caledonia in waters between 5 and
40 m in depth. Although in shallow waters the composition of the New Caledonia target stocks
Table 13: Summary of catch rate and catch composition data for long-line fishing on
coral reef and associated stocks in the South Pacific region.
CPUE (kg100hooks-l) Principal catch
Location Target stock range mean components Source
New Caledonia Shallow reef 3.0 – 12.2 8.2 Lethrinidae, Kulbicki &
species Serranidae, Grandperrin
Labridae, 1988
Chuuk Outer Deep slope 1.6 – 12.3 6.8 Lutjanidae, Diplock &
Banks species Carangidae, Dalzell 1991
Tonga Deep slope na 11 Lutjanidae, Mead 1987
species Serranidae,
Fiji Deep slope 12.5 – 29.2 19.1 Lutjanidae, Walton pers.
species Serranidae comm.
Vanuatu (Paama (Fig 2, Deep slope 10 – 92.5 33.7 Lutjanidae, Fusimalohi &
76) & Espiritu Santo) species Serranidae, Preston 1983
Vanuatu (Espiritu Deep slope 15 – 389 124.6 Lutjanidae, SPC unpub.
Santo) species Serralridae, data
at the family level was closer to that from deep-slope fishing than from reef areas, their
inclusion in Table 13 allows for some comparisons to be made with deep-slope catch rates.
Seasonal trends in catch rates of deep-slope fishes have been reported from Vanuatu (Brouard
& Grandperrin 1985) and from Tonga (Latu & Tulua 1991). In Vanuatu catch rates for E.
carbunculus and E. coruscans reached a maximum between February and June, with minima
towards the year’s end. Maximum catch rates of Pristipomoides flavipinnis and P. multidens
were observed between April and July. By contrast the CPUE for Lutjanus malabaricus was at
a maximum during December and lowest in June and July. There was little evidence of
seasonality in CPUE from the total catch from the deep-slope fishery in Tonga; however,
individual species had very clear seasonal maxima in Tonga. The CPUE of both Pristipomoides
filamentosus and P. flavipinnis were lowest in September and highest in December-January.
Etelis coruscans was observed to have two peaks in CPUE, during May and during November,
while only a single peak in CPUE was observed for E. carbunculus during November. Two
seasonal peaks in CPUE were also observed from catches of Lethrinus chrysostomus, during
February and July. The seasonal pattern for Epinephelus morrhua resembled that of the
Pristipomoides spp., but with a peak in April and a low point in August. The seasonal pattern
for Epinephelus septemfasciatus showed a strong peak in CPUE during May.
Variation in catch rate with depth and time of day has been investigated in Vanuatu (Brouard &
Grandperrin 1985) and PNG (Richards & Sundberg 1984). Brouard & Grandperrin (1985)
concluded that there was little difference between day and night catch rates, but that when the
data were broken down by 40 m depth intervals, catch rates were greatest in shallow water at
night. Richards & Sundberg (1984) reported on a study that was specifically designed to test the
differences in CPUE among depths and times of day. They found that peaks in CPUE occurred
progressively later in the day from the deepest to the shallowest depths over 24 h. Dalzell &
Preston (1992) summarized the information from surveys of deep-slope stocks to investigate
the interaction of depth and time of day on deep-slope catches. CPUE increased with increasing
depth between 50 and 150 m, was constant between 150 and 250 m, and declined with
increasing depth between 250 and 450 m. Hourly catch rates showed no particular pattern in
shallow waters, but resolved into peaks at 12.00 and between 22.00 and 02.00h at depths
beyond 200 m. The average pattern of catch rates over a 24 h period, for all depths, produced
peaks at 12.00, 15.00, 20.00 and 03.00h. Ralston et al. (1986) found that the abundance of fish
at Johnson Atoll peaked at 170 m depth with a smaller minor peak at 250 m. Overall, the pattern
of abundance was similar to the depth pattern of catch rates observed from survey fishing data
by Dalzell & Preston (1992). Ralston et al. (1986) found that on average, catch rates were twice
as high in the morning than in the afternoon but that catch rate began to improve with the onset
of the evening crepuscular period.
The foregoing data do not include information on individual species captured and the resultant
patterns in CPUE with depth and time of day are the result of various species interactions.
Haight et al. (1993) reported the results of experimental fishing on the outer banks of the
Hawaiian Islands for eteline snappers using hand-lines and long-lines. This study showed that
overall CPUE in numbers of fish fluctuated throughout the diel cycle and peaked during the
crepuscular periods (04.00 to 06.00h and 18.00 to 20.00h). Catch rates of individual species
also fluctuated markedly, with Pristipomoides spp. and Etelis cornscans being caught mainly in
the morning, in contrast to E. carbunculus, which was captured mainly during the evening and
night. Other species, such as Aprion virescens, were captured throughout the day but generally
not at night.
Fisheries biology and stock assessment
Unlike shallow water reef fishes, there has been a considerable amount of stock assessment
research and biological studies made on Pacific deep-slope fish stocks. A series of review
papers on deep-slope fish biology and stock assessment was edited by Polovina & Ralston
(1987). Age, growth and related biological studies commenced on deep slope species in the
Pacific during the 1980s, principally on the eteline species with the intent of monitoring the
effects of fishing and conducting stock assessments. Ralston (1981) presented an account of the
population biology of Pristipomoides filamentosus in the Hawaiian Islands that included a new
approach to ageing long-lived fishes from daily growth increments. The same method, which
has also been described in detail by Ralston & Miyamoto (1981), does not require a complete
reading of the growth record in the otolith microstructure but only requires several counts of
increment densities at successive distances from the otolith core so that these can be integrated
to give a complete estimate of the age of the fish.
This methodology has been used to age several deep-slope species from the Northern Mariana
Islands (Ralston & Williams 1988b), PNG (Richards 1987) and Vanuatu (Brouard &
Grandperrin 1985). A comparative study of the age and growth of Etelis carbunculus from
Hawaii, Northern Mariana Islands, Vanuatu and French Polynesia was made by Smith &
Kostlan (1991) using Ralston’s technique. They were able to show that there were major dif-
ferences in age at length for the four widely separated stocks of the same species. Other
estimates of growth of deep-slope species have been made by analysis of length frequency data
from Vanuatu (Carlot 1990) and Tonga (Sua 1990, Mees 1994). Most of the studies listed above
have computed mortality rates for deep-slope species from length frequencies, catch curves or a
combination thereof. Deep-slope species typically have life spans of between 20 — 30 yr, with
concomitantly low natural mortality rates. Ralston (1987) has reviewed the mortality rates of
deep-slope snappers and groupers and has suggested that agents responsible for natural deaths
in these species include predation, parasitism, cold water shock and red tide poisoning. Ralston
(1987) has also reviewed information from fisheries for tropical deep-slope snapper and
grouper species and concluded that these species have a relatively limited productive capacity
and are vulnerable to overfishing.
Two basic approaches have been used to estimate the MSY from deep-slope fish stocks in the
South Pacific: multi-species surplus production models where the catch of all or a group of the
commonest species are combined and plotted against effort; and biomass estimation and yield
calculations based on biological characteristics. A third method for assessing deep-slope stocks
is to conduct direct observations on fish populations in situ while conducting survey fishing.
Such a series of observations has been made by Ralston et al. (1986) at Johnson Atoll, where
survey fishing was complemented by a series of deep-slope fish abundance estimates made
from a small submersible. More recently, Ellis & DeMartini (1994) have correlated estimates of
abundance of juvenile Pristipomoides filamentosus and other Hawaiian deep-slope fish made
by a remote video camera with demersal long-line catch rates targeted at the same stocks.
However, such methodology, requiring expensive specialized technologies and skills, is
unlikely to be commonly used in the Pacific.
Ralston & Polovina (1982) fitted a multi-species version of the Schaefer stock production
model to catch and fishing effort data from a deep-slope hand-line fishery on the banks between
the islands of Maui, Lanai, Kahoolawe and Molokai (Fig. 2, 57) in Hawaii. They found that the
annual predicted MSY was 106 t or 272 kgn.mi-1 of 100 fathom isobath. Ralston & Polovina
(1982) explained that expressing yield per linear measure was probably more appropriate for
steep-sided islands than the use of an areal or planar measure. Other authors have adopted this
convention and expressed yields as kgn.mi-1 of 100 fathom or 200 m isobath. Elsewhere, King
(1992a) fitted simple Fox and Schaefer production curves to data for catches of the five
principal species (P. filamentosus, Etelis carbunculus, E. coruscans, Epinephelus
septemfasciatus and E. morrhua) in the Tongan deep slope fishery. King (1992a) found that the
MSY predicted by the two models was 255 and 284 tyr-1 respectively. A similar analysis for all
demersal species suggested MSYs of 400 and 560 t respectively, but the fit to the data was
rather poor. The length of the 200 m isobath in Tonga is estimated to be 294 n.mi (Lam & Tulua
1991) thus the yields estimated from King’s (1992) analysis range from 0.87 to 0.97 tn.mi-1 for
the principal five species to between 1.36 and 1.90 tn.mi-1 for the total demersal catch.
The other approach to estimating MSY from deep-slope stocks in the South Pacific is to use
depletion models to estimate the unexploited biomass and then, using the biological char-
acteristics of the stock, estimate what fraction of the virgin biomass can be harvested. The
simplest approach has been to conduct short-term intensive fishing experiments to generate
cumulative catch and CPUE data for use with a Leslie stock depletion model (see p. 420). For
situations where fishing has commenced and longer time series of catch and effort data are
available, then Allen’s (1966) method, which incorporates natural mortality rates and
recruitment, is more appropriate.
Polovina (1986) used the simple short-term Leslie depletion method to estimate the biomass
and catchability coefficients of deep-slope fishes in the 175 to 275 m depth range, from a
13-day intensive fishing experiment at a small pinnacle reef in the Northern Mariana Islands.
Based on these results and with further fishing at most of the islands and seamounts in the
Northern Mariana Islands, Polovina & Ralston (1986) were able to estimate the total biomass of
deep-slope fishes in this archipelago and the MSYs for the seven principal species in the catch,
namely, one jack, Caranx lugubris, and six snappers, Pristipomoides zonatus, P. auricilla, P.
filamentosus, P. flavipinnis, Etelis carbunculus, and E. coruscans. They suggested that the
MSY for the deep-slope stocks of Northern Mariana Islands was about one-third of the original
unexploited biomass, which ranged between 0.260 and 1.207 n.mi-1 of 200 m isobath with a me
an of 0.675 tn.mi-1 200 m isobath, giving an MSY of 0.22 tn.mi-l of 200 m isobath or an absolute
value of 109 t.
The more complex approach to estimating biomass and yield using Allen’s method has been
employed by Langi et al. (1988) for deep slope fisheries on seamounts around the Tongan
archipelago. They stated that the average surplus production or MSY from three seamounts was
0.74 tn.mi-1 of 200 m isobath, or an absolute value of 217 t for the 294 n.mi of 200 m isobath in
Tongan waters. The Allen and Leslie depletion methods were both used to estimate biomass
and MSY for several other locations in the South Pacific and are presented in a series of papers
contained in Polovina & Shomura (1990). These locations include banks and seamounts in Fiji,
island slopes in Vanuatu and island slopes and seamounts in PNG, as well as a re-analysis of the
data from Tonga using an extended data set. A summary of these estimates was presented in
Polovina & Shomura (1990), which suggested that the unexploited recruited biomass ranged
from 0.2 to 7.0 tn.mi-1 of 200 m isobath, and that MSY lay in the range of one-tenth to one-third
of the unexploited virgin biomass.
Mees (1994) re-analyzed catch and length frequency data from the Tonga deep-slope fishery
and fitted a dynamic production model to catch and effort data from the Tongan fishery to
obtain a total MSY of 588 t. Using a modification of Allen’s model, Mees (1994) estimated a
yield of 0.50 — 0.77 tn.mi-1 of 200 m isobath for a guild of six main species in the fishery
(Pristipomoides filamentosus, P. jlavipinnis, Etelis carbunculus, E. coruscans, Epinephelus
septemfasciatus and E. morrhuaf, and of 0.33 — 0.63 tn.mi-1 of 200 m isobath for
Pristipomoides filamentosus only. Mees (1994) noted that individual species’ catch rates
showed an increase over time for Etelis cornscans and a decrease for Pristipomoides
filamentosus. This was due less to depletion, however, than an increasing trend to fish deeper to
target for E. coruscans which was more valuable on export markets. Mees (1994) did conclude,
however, that there might be some fishing-induced effects between E. coruscans, and
Epinephelus septemfasciatus, with catch rates of the former species increasing as populations
of the latter are reduced. Mees (1994) reasoned that E. septemfasciatus is the largest fish ex-
ploited in the fishery and large specimens will not be replaced rapidly. As they are fished out,
the remaining smaller specimens provide less competition to Etelis coruscans for the baited
hooks and hence the catch rate of this species increases. Indeed, Mees notes that fishermen in
Tonga report actively fishing for this species in order to remove it in order to increase catches of
E. coruscans.
A similar observation was made by Polovina (1986) during short-term intensive fishing
experiments in the Northern Mariana Islands. Polovina noted that as the catch rates of
Pristipomoides zonatus and Etelis carbunculus declined during the 13 day fishing experiment,
the catch rate of Pristipomoides auricilla showed a marked increase. Polovina suggested that
the interaction of P. auricilla and Etelis carbunculus was unlikely to be attributable to the latter
species living at greater depths. However, species interaction would most likely occur between
P. zonatus and P. auricilla that were more abundant in the same depth interval (100 — 120 m).
Polovina (1986) reasoned that if P. zonatus was more aggressive in pursuing fish baits than P.
auricilla, or in some other way affected the behaviour of the latter, then the initial catchability
of P. auricilla would be low but would rise as the population of P. zonatus was reduced.
Polovina (1986) modified the simple Leslie depletion model to account for this species
Socioeconomic developments
Only one deep-slope fishery of any significance (Tonga) persists in the South Pacific. Despite
the initial optimism that was generated by the exploratory surveys on virgin stocks in the
Pacific, it was not immediately appreciated that these populations comprised large, slow
growing species, and that most countries of the region, by virtue of their size, had limited stocks
that could withstand only moderate exploitation. In human terms this meant that deep slope
fisheries must remain small and indeed the Tongan fishery has survived only by reducing fleet
size by half and maximizing the value of the catch by exporting P. filamentosus and Etelis
coruscans to Hawaii.
The access to overseas markets and the importance this has played in the survival and collapse
of deep-slope fisheries cannot be emphasized too strongly. The same is also true of the growing
interest in catching large valuable tunas for the Japanese market (see p. 451). PNG has by far
the largest resource of deep-slope fish in the region by virtue of the extent of the 200 m isobath.
Furthermore, these stocks have been shown to be productive and could probably generate
between 500 to 1500 tyr-l at MSY (Dalzell & Preston 1992). However, PNG does not have