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Distribution of commercially important fish species of Curieuse Marine National Park

Authors:
Draft Report, 1997
Distribution of commercially important fish species
of Curieuse Marine National Park
Simon J. Pittman
Seychelles Marine Conservation Expedition, Nov-Dec, 1996
Introduction
Coral reef associated fisheries provide an important source of economically affordable animal protein for the
populations of the Seychelles. In addition to satisfying the domestic market, demersal fishery supports a
buoyant export market of fresh and frozen fish. Demersal nearshore fish are primarily caught from small
boats, including pirogues and small boats with both outboard and inboard motors using a variety of gear
types. Highest effort and catch rates are from outboards using handlining, traps and encircling gill nets.
From 1990 to 1994, the catch from the small boat fishery of Praslin and La Digue includes a large range of
demersal and pelagic species. Pelagics comprise a large proportion of the catch recorded at landings from
small boats, including Carangidae (Jacks), Scombridae (Tuna/Mackerels) and Caesionidae (Fusiliers) and
others. This accounted for some 47% of the catch from 1990 to 1994. The remaining component of the
catch were species associated with coral reefs or have largely nearshore demersal life histories. These fish
were largely the Lutjanidae (Snappers) and Lethrinidae (Emperors) 18.8%; the Siganidae (Rabbitfish),
15.2%; other trapfish including Acanthuridae (Surgeonfish), Scaridae (Parrotfish), Haemulidae (Sweetlips)
and Mullidae (Goatfish) and others, 12.8%; Serranidae (Groupers), 3% and Sphyraenidae (Barracuda) caught
mainly with handlines making up a very small proportion. Other significant catches included sharks, rays and
octopus. These figures give some indication of the importance of particular target fish families to the
artisanal fishery of Praslin. Further analysis shows a declining catch rate over 5 years from 54.2 kg/boat/day
in 1990 to 36.03 kg/boat/day in 1994. Although these types of statistics are prone to large variations and a
longer time scale study would be necessary to elucidate a trend. Most notably, landings of grouper have
declined significantly from 16.8 MT in 1990 to 4.4 MT in 1994 in the Praslin and La Digue fishery. In this
time statistics show a general increase in effort i.e. mean number of boats (SFA, 1990-94).
Fisheries biologists in the Seychelles have suggested that the average catch of recent years is close to
sustainable levels and that future exploitation must be closely monitored (Khadun, 1991). Efforts are being
taken to encourage exploitation of fish stocks further offshore by improving the design and long-range
efficiency of boats and their engines. This is a management strategy designed to relieve pressure on near
shore populations and provide a refugia that will allow populations to increase to a more sustainable level
and provide for a smaller scale nearshore artisanal fishery. Statistics show a general decrease in mean
number of Pirogues operating per month (185 in 1985 to 64 in 1994) and increase in number of whalers
(from 37 in 1985 to 91 in 1994) indicating an increased mechanisation of the Seychelles artisanal fishery
fleet.
Data collected from landing sites within the Curieuse MNP boundary (Anse Boudin, Baie Pasquiere and
Anse Possession) by the SFA show a small increase in the number of outboards and inboards used and a
general decrease in catch. This may not necessarily include catch within the MNP, but rather gives an
indication of local fishing intensity and perhaps a reflection of the larger trends in the Seychelles artisanal
fishery. Data is unavailable for catch composition at these landing sites. The recorded catch landed at
Curieuse MNP sites on Praslin comprised some 8 % of the total Praslin small boat fishery catch. This is not
a large proportion and it has become smaller over the 5 year period between 1990 and 1994. Although catch
data was not analysed prior to 1990 it is likely that this area yielded a greater proportion of the total Praslin
catch in earlier years. This assumption is supported by comments from local fishermen. However, it may
also be the case that fisherman land larger catches at other sites, such as Anse Volbert which is within
economical range.
At some sites in the park, broken and discarded fishing lines were found, particularly at the Praslin coast site
at Anse Petit Cour. This particular site had been cleared of lines some months before by local divers and this
then would indicate the importance of this reef to local fisherman. It is not known whether the lines
belonged to licensed fishermen.
In order to quantify the distribution of commercially important food fish in coastal waters, visual census was
used with estimates of species diversity, abundance and size recorded at each site. This technique together
with a knowledge of fishing activity in an area is often used to help assess the status of these populations and
to provide resource managers with baseline information which may help in the design of management plans.
Methodology
Transect based visual census was undertaken at 9 sites within Curieuse MNP. Non-transect observations
were made at an additional site in the park and two sites further afield and outside the park (Ile aux Cocos
and Marianne). The technique used followed that outlined for the Reefwatch methodology for non-
commercial fish assemblages, but included size estimation. At the two sites outside the park single 20
minute counts were undertaken.
Size estimation - it is important to estimate the size of fish in the census area in order to be able to
extrapolate information on the age class structure i.e. relative numbers of juveniles and adults. In fished
areas population age structures often become distorted, whereby older and larger fish become increasingly
rare. Information can also be collected from fisheries depots for comparison. This study used 3 size classes
for recording estimated individual fish lengths; < 20 cm, including juveniles; 21-30 cm and 31-50 cm; no
individuals were recorded above 50 cm within the transect survey band.
The survey for commercial species targeted four families; Serranidae (Groupers), Lutjanidae (Snappers),
Lethrinidae (Emperors) and Haemulidae (Sweetlips).
Groupers typically include many of the largest fish seen on the reef. They are the largest top quality edible
fish (target fish) and of considerable commercial value and often the fish that are first depleted as fishing
pressure increases. Estimates of size and abundance provides important information for assessing the impact
of fishing and for monitoring the reef community.
Snappers, Emperors and Sweetlips are three related families of similarly typically shaped medium sized
fish. All are important predators of invertebrates and fish. After the grouper these types of fish are usually
the next to decline in number as fishing intensity increases.
Trap fisheries include many reef associated fish species that will not be dealt with in this section.
Commercial fish survey results
Groupers - Throughout the survey area 15 species of Epinephelini groupers were identified, however, only
10 species were recorded within the survey band. These species and the mean abundance per size class at
each site are shown in the table fig. 1c. Fig. 1a and fig. 1b show the abundance and species richness at each
site.
Highest abundance and species richness was found at coralline reefs. Anse Petit Cour yielded greatest
diversity and abundance. Most of these individuals were less than 20 cm in length. Most noticable were the
relatively large number of juvenile Anyperodon leucogrammicus and this reflected the complexity or
rugosity of the substrate and the preponderance of prey species. This species is shy and quickly retreats to
cover if approached. Plectropomus species were also comparatively abundant at this site with juveniles
appearing to prefer deeper areas on the reef slope. Cephalopholis argus a primary target species for the
artisanal fishery is well represented at all size classes across the survey area, but is only found at full adult
size at Anse Petit Cour and Turtle Reef. The coralline sites at Coral Gardens with similar reef substrate
complexity have fewer grouper species and lower abundance than Anse Petit Cour. Another primary target
species is Aethaloperca rogaa. This species is represented in highest abundance at Point Rouge and Coral
Gardens. Generally, granitic sites yielded lower abundance and diversity than coralline sites. Wolfgang
Wall had highest diversity of the granitic sites but showed low abundance and a preponderance of small
individuals (all <30 cm). Fully grown adult individuals of A. rogaa and C. argus (primary target sp.) were
only recorded for coralline reefs, with highest abundance on the Praslin coastline at Anse Petit Cour and
Turtle Reef (refer to table fig. 1c).
Previous surveys at Baie Ternay and Beau Vallon show similar size class distribution and diversity but
slightly higher abundance with a preponderance of small - medium individuals (<30 cm). However,
diversity and abundance at Anse Petit Cour exceeds all sites thus far surveyed by our group on Mahe or
Praslin. Comparison with surveys in Kenya using the same techniques and some of the same observers
show similar size structure to those recorded in fished areas of marine reserves but abundance more closely
to records of fish in protected parks i.e. with lower fishing intensity (Watson and Ormond, 1994, TMRU,
1993, TMRU, 1994, TMRU, 1995). Results from studies in Kenya also suggest a slower recovery time for
populations of Serranids depleted by artisanal fisheries than for other commercial families such as the
Lutjanids.
Habitat correlates are an important consideration and Serranidae are generally found in higher abundance at
coral rich areas with plentiful prey species and adequate substrate structure providing refuge or hiding
places. This is evident at Anse Petit Cour but does not account for the comparatively low abundance and
species diversity at Coral Gardens, since this site is also coral rich with high rugosity and high prey fish
abundance. Differences may be due to extraction due to fishing since individuals at these two sites were
almost all less than half fully grown. However, differences could be attributed to spatial patterns in
recruitment and site preferences such as reef profile and physical protection through embayment as at Anse
Petit Cour and Turtle Reef.
St. Pierre, a shallow granitic transect showed lowest abundance and diversity and largely this can be
attributed to habitat type. Shallower transects on granitic reefs may also have excluded larger Serranidae
which generally prefer deeper water coral rich sites.
Other studies in Seychelles have compared reef fish assemblages exposed to varying levels of fishing
intensity to show significant differences in Serranidae abundance and biomass, suggesting Serranids are
particularly effective direct indicators of fishing pressure. Jennings (1994 draft, 1996) showed that primary
target species including Cephalopholis argus were found to contribute significantly to total biomass of the
reef fish community in the well protected areas with no or little fishing effort. Although estimated biomass
calculations were not used in this current study, data on size and abundance show that primary target species
of Serranidae would not contribute a significantly high proportion of biomass within the fish assemblages at
most of the sites in Curieuse MNP.
Relatively high site attachment for groupers would suggest increased importance in the protection of
coralline reefs, particularly areas such as Anse Petit Cour and Turtle Reef since these areas appear to be
importance nursery areas maintaining high diversity and abundance of important piscivores and
commercially valuable Serranidae.
Snappers, Emperors and Sweetlips - 7 species of Lutjanids, 10 species of Lethrinids and 4 species of
Haemulids were identified throughout the marine park. 5 species of Lutjanids, 8 species of Lethrinids and 3
species of Haemulids were recorded within the survey bands. These were almost all primary target species
for the artisanal fishery. Highest abundance was recorded at Coral Gardens 1 with high mean abundance
being comprised primarily of small-medium (<20) Lutjanus kasmira; medium-large (31-50 cm + several
larger) Aprion virescens; a large group of medium sized and juvenile L. bohar and small-medium (<20)
Lethrinid species (refer to fig. 2c) Highest diversity was recorded at Turtle Reef with a higher diversity of
Lethrinids and Haemulids than other sites. L. kasmira defined as a secondary target species was only
recorded at the Coral Garden sites (refer to figs. 2a, 2b).
Several small Lethrinus nebulosus were recorded foraging close to the substratum at granitic sites with
expanses of sand and rubble, particularly at Roche Canon. Solitary L. obsoletus, L. mahsena and L. harak
were more commonly seen over coralline reefs. Monotaxis grandoculis was recorded at all sights apart from
Coral Gardens 1. Most of these fish were juveniles showing distinctive juvenile colouration and particularly
young/small individuals were recorded at Anse Petit Cour and Turtle Reef. Two large adults were recorded
at Coral Gardens 2.
In addition, coralline reefs were characterised by large mixed species shoals of Caesionidae (Fusiliers) and
occasional groups of large roving Carangids. A large group of Caranx melampygus were observed feeding
on a cluster of fish larvae at Anse Petit Cour.
Granitic sites are characterised by large aggregations of boulders which in many places create ideal
protective habitats with caves, gullies and overhangs. At other areas in the Seychelles this type of habitat is
often occupied by mixed aggregations of Lutjanids and the more recluse Haemulids. At Roche Canon a
small group of L. fulviflamma were recorded amongst the boulders and a large group of small
Plectorhynchus sp. sheltered in cave like structures at Roche Canon and St. Pierre. However, to some extent
this type of habitat appeared under utilised at many of the granitic transects at Curieuse MNP. Particularly
low abundance and diversity at Wolfgang Wall may in part be linked to limited habitat diversity with large
areas of monospecific soft coral covered granite and low sand and rubble cover within the transect band
(refer to fig. and fig. 4). Other authors (Sainsbury, 1988) have recorded shifts away from community
dominance of Lutjanids and Lethrinids with a decrease in structural heterogeneity of the substrate.
For comparative purposes additional sites were visited, primarily for observations of commercial species.
One site within the park which was poorly known and not as easily accessible from the shoreline and two
sites (Ile aux Cocos and Marianne South) several kilometres outside the park were visited. Reconnaissance of
a 9-10 m sand and patch coral plateau in the middle of the park revealed strikingly different assemblage
structure to any of the other areas surveyed. Shoals of some 400 Lutjanus kasmira were recorded, large
numbers of adult and juvenile L. sebae, moderate numbers of Lethrinids and the only sightings of Lethrinus
enigmaticus and the distinctive looking emperor Gnathodentex aurolineatus. In addition, several conger eels
(Conger cinereus) and large numbers of the grouper Epinephelus fasciatus were seen. Pelagic species were
also abundant and large numbers of Carangids and Caesionids were common. Animals were noticeably
more curious than at any other site and this reflected the absence of any significant disturbance.
Counts at Marianne were undertaken over granite boulder/cliff and sand substrate. Moderate numbers of
commercially important species were recorded including 37 medium-large L. kasmira, 18 medium L.
fulviflamma, 30+ large Macolor niger high in the water column between granite boulders, 7 juvenile
Monotaxis grandoculis, several large Haemulids and solitary Lethrinus sp.
Counts at Ile aux Cocos were undertaken over living coralline substrate, wave damaged coral and
sand/rubble. One large shoal of L. kasmira (300+) were recorded. Lethrinid species were not well
represented and included L. obsoletus and L. nebulosus. 8 L. bohar were recorded, 5 of which showed
advanced juvenile colouration and one swam around with a large fishing hook with a length of nylon line
embedded in its flank.
Visual fish census at Baie Ternay and Beau Vallon (TMRU, 1996) showed lower diversity and abundance at
almost all survey sites. This reflects a higher fishing intensity as might be expected nearer a larger fishing
population. Jennings (1994 draft, 1996) found correlation’s between Lutjanid and Lethrinid species diversity
and fishing intensity whereby significantly less species were recorded in areas of higher fishing pressure. In
the current study at Curieuse MNP, diversity of commercial species alone can not be used as an indicator
since large site to site variations in substrate were found and adequate measures of fishing effort per site
could not easily be estimated. If a general correlation is accepted patterns of distribution recorded at
Curieuse MNP would indicate highest fishing intensity at Wolfgang Wall and Coral Gardens 2. Studies by
the TMRU in Kenya show comparable counts at coralline sites in a reserve having been exposed to moderate
- heavy fishing pressure. However, the large numbers of Lutjanids recorded at the mid-park plateau and the
large abundance and diversity of both Lethrinids and Lutjanids at Coral Gardens 1 more closely resembles
counts at some of the protected park sites in Kenya. This may suggest that commercial fish populations at
Curieuse MNP are intermediate between that expected for a protected park and that expected for an area
subjected to moderate-heavy fishing intensity, if habitat differences were not highly correlated with observed
patterns. Results show many habitats in the park with low populations of commercial species and highlight
the importance of undisturbed areas for the maintenance of commercially viable populations.
Commercial fish utilization of Mangroves at Baie Laraie, Curieuse
Extensive stands of mangrove species grow landward of a stone causeway at Baie Laraie on Curieuse. The
plant species include Rhizophora mucronata, Sonneratia sp., Lumnitzera sp., Avicennia marina, Xylocarpus
granatum and X. moluccensis. The enclosed area is subjected to the tidal regime and regularly flushed
although never entirely emptied at low tide. Substrate is fine-coarse sediment with dense molluscan
assemblages contributing to the coarser sediment. Brackish water algae is abundant and in some areas forms
extensive floating mats. Seaward of the causeway is a fringing reef with relatively young hard coral
communities and extensive algae growing over older carbonate structures. In some deeper areas Acropora
sp. form thickets and reef associated species are diverse.
Observations were made at low tide (0.2 - 1 m deep) along the seaward edge of the vegetation. Juveniles of
Monodactylus argenteus were abundant and this habitat provides for the young of the larger populations
(200+) of adults observed at Roche Canon. Other juveniles included Sphyraena sp. (Barracuda), L.
fulviflamma inside and on surrounding algal flats and several juvenile parrotfish. L. harak and L. obsoletus
adults and adult Haemulids were seen sheltering under algal mats and around the raised pipeline which
appeared to act as an attractant, providing a permanent structure across the sediment. Larger numbers of
unidentified commercial juvenile fish and prawn were seen amongst the plant roots. It is likely that this
habitat has significant value as a nursery for some species and a feeding area for others. Monodactylids are
intimately associated with this type of habitat and adults were also seen in large numbers over shallow reef
areas near the mangroves at Baie Ternay. Survey at high tide may reveal a higher proportion of reef
associates utilizing this habitat.
References
Jennings, S., Grandcourt, E.M. and Polunin, N.V. (Draft copy, 1994) Effects of fishing on the diversity,
biomass and trophic structure of Seychelles‘ reef fish communities.
Jennings, S., Marshall, S., and Polunin, N. V. (1996). Seychelles marine protected areas : Comparative
structure and status of reef fish communities. Biological Conservation, 75, 201-209.
Khadun, A. (1991). Ecological research in the coastal lagoons of the Republic of Seychelles. In Workshop
on Tropical Coastal Lagoon Ecosystems, Inhaca Island, Mozambique. Dec 3-5, 1991. SAREC
DOCUMENT.
Sainsbury, K.J. (1988). The ecological basis of multispecies fisheries, and management of a demersal
fishery in tropical Australia. In Fish Population Dynamics eds. J.A. Gulland. pp. 349-382. Wiley.
SFA, 1990-1994. Seychelles Artisanal Fisheries Statistics. SFA Technical Report. SFA, P.O. Box 449,
Mahe, Seychelles
TMRU (1993) Report on the distribution of fish species between Kisite Marine National Park and Mpunguti
Marine National Reserve. Tropical Marine Research Unit, University of York.
TMRU (1994) Habitats and species of the Diani coast, Kenya. Tropical Marine Research Unit, University
of York.
TMRU (1995) Habitats and species of the Malindi and Watamu National Marine Reserve, Kenya. Tropical
Marine Research Unit, University of York.
TMRU (1996) Habitats and species of Baie Ternay MNP and Baie Beau Vallon, Mahe. Tropical Marine
Research Unit, University of York.
Watson, M. and Ormond, R. F. G. (1994) Effect of an artisanal fishery on the fish and urchin populations
of Kenyan coral reef. Mar. Ecol. Prog. Ser., 109, 115-129.
Fig 1a. Serranid abundance and species richness at Curieuse Marine National Park
2
7
9
2
5
3
3
4
3
0
10
20
30
40
50
60
70
80
Coral Gdns 1
Coral Gdns 2
Point Rouge
Curieuse Reef
Wolfgang wall
Roche Canon
Anse Petite Cour
Turtle Reef
St Pierre
Sites
Mean number of fish
per 2500m
2
Fig 1b. Serranid abundance classes for Curieuse Marine National Park
Sites
Species
CG1 CG2 Point
Rouge
Curieuse
Reef
Wolfgang
Wall
Roche
Canon
Anse
Petite
Ceour
Turtle
Reef
St.
Pierre
Aethaloperca rogaa
o
Anyperodon. leucogrammicus
o o
o
Cephalopholis argus
C. miniata
o
o
o
Epinephelus caeruleopunctatus
o o o o o o o o o
E. tauvina
o o o o o o
o o
E. fuscoguttatus
o o o o o o
o o
E. malabaricus
o o o o o o o
o
E. polyphekadion
o o o o o o
o o
Plectropomus laevis
o o o o o o
o
P. punctatus
o o o o
o
o
o
0
1-5
6-10
11-20
Key for abundance classes
(individual fish per 2500 m
2
)
Fig 2a. Lutjanid, Lethrinid and Haemulid abundance and species richness at Curieuse
Marine National Park
8
10
7
8
3
8
8
6
8
0
10
20
30
40
50
60
70
80
Coral Gdns 1
Coral Gdns 2
Point Rouge
Curieuse Reef
Wolfgang wall
Roche Canon
Anse Petite
Ceour
Turtle Reef
St Pierre
Sites
Mean number of fish
per 2500m
2
Fig 2b. Lutjanid, Lethrinid and Haemulid abundance classes for Curieuse Marine National Park
Sites
Species
CG1 CG2 Point
Rouge
Curieuse
Reef
Wolfgang
Wall
Roche
Canon
Anse
Petite
Ceour
Turtle
Reef
St.
Pierre
Lutjanus fulviflamma
o o
o o
o o o
L. bohar
o o
o
L. gibbus
o o o o o o o o o
L. kasmira
o o o o o o o
Macolor niger
o o o
Lethrinus harak
o
L. elongatus
o o o o o o o
L. mahsena
o o o o o
L. microdon
o o o o o o o o
L. nebulosus
o o
o
o
o
L. obsoletus
o
o
L. variegatus
o
o o o
o
M. grandoculus
o
Aprion virescens
o o
o
Plectorhynchus spp.
o o
o o
o 0
1-5
6-10
11-20
31-50
Key for abundance classes
(individual fish per 2500 m
2
)
... Cette espèce est l'une des principales capturée au chalut dans le golfe d'Aden (Aldonov et Druzhinin 1979) et elle constitue l'une des espèces principales des pêcheries démersales dans le golfe Persique (Grandcourt et al. 2006). L. nebulosus est une espèce commerciale importante aux Seychelles et s'y rencontre surtout sur les fonds détritiques (Pittman 1997 Il existe en effet une corrélation entre taille et profondeur ainsi qu'une évolution de l'abondance en fonction de l'habitat. Aucune migration n'est connue, mais il est probable que cette espèce vient pondre dans des zones peu profondes à proximité des îlots, de préférence dans les zones présentant un peu de courant. ...
Article
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Effective management of Seychelles' reef resources is essential because the conflicting demands of fishing, tourism and conservation must be reconciled if sustainable development and the protection of natural resources is to be assured. Marine protected areas play a key role in the existing management strategy and yet there is little quantitative understanding of the benefits they may provide. We compare the biomass and species richness of fish assemblages on coral and granitic reef habitats in four areas which receive different levels of protection from fishing and other human activities. Species richness of the total fish community, biomass of the total fish community and species richness and biomass of many families were higher on both coralline and granitic reefs in two marine protected areas where protective regulations were effectively enforced. However, the biomass of the three principal families of fishes targeted by the fishery was significantly lower in one of these areas. This was attributed to illegal fishing and the fishing concessions offered to local people. We conclude that poaching and minor fishing concessions did not affect the aspects of the fish community which are important to most tourist visitors (biomass and overall species richness), but that they have a statistically significant effect on the structure of the fish community. Furthermore, whilst a small well-patrolled area will provide an effective refuge from fishing, it will often be stocked by larval fishes which are the progeny of adults living many kilometres away. As such, the protected area cannot operate in isolation to maintain biomass and diversity. A valid longterm aim of reserve management may be to assure the protection of a greater proportion of Seychelles' fishes throughout their life history. This may be achieved if current plans for the management of marine protected areas can be instituted.
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A fishery independent underwater visual census technique was used to assess the effects of fishing on the diversity, biomass and trophic structure of the diurnally active non-cryptic reef- associated fish communities of the Seychelles. One hundred and thirty four species associated with three significantly different types of reef habitat were censused at one unfished ground and in six fishing grounds subject to different fishing intensities. There was an inverse relationship between fishing intensity and the biomass of several species targeted by the fishery. The diversity of families containing target species (lutjanidae, lethrinidae) was significantly higher at unfished and lightly fished sites as was the total biomass of the fish community and the biomass of piscivorous, piscivorous/invertebrate feeding and herbivorous trophic groups. However, there was no indication that the biomass of non-target species increased in response to the removal of their predators by fishing. The findings of this study are significant for fishery managers because they suggest that the intensive differential cropping of top predators will not necessarily lead to increases in the biomass and productivity of their prey.
Article
An investigation of the effects of artisanal fishing on coral reef fish assemblage structure was undertaken through a comparison of fish stocks on 2 apparently identical sets of reefs, one (within the Kisite Marine National Park) on which all fishing is prohibited, and one (within the Mpunguti Marine National Reserve) on which artisanal fishing only is allowed. Replicate visual censuses of fish along 250 x 10 m band transects at 6 intensive study sites demonstrated that there were large differences in population density and biomass of the principal families of commercial reef fish (Lethrinidae, Lutjanidae and Serranidae) between the unfished marine park area and the adjacent intensively fished marine reserve area, with abundances of commercial species within the park (unfished) being up to 10 or more times those in the reserve (fished). In addition, 6 species of butterflyfish (Chaetodontidae) and 2 species of triggerfish (Balistidae) were significantly more abundant on shallow and/or deep transects within the park. For most species of commercial fish, larger individuals were observed in the park than in the reserve, an effect expected from greater fishing pressure within the reserve. In contrast, smaller Cephalopholis spp. (Serranidae), 1 species of butterflyfish, and sea urchins (mostly Echinometra mathaei) were significantly more abundant on transects in the reserve. It is suggested that these increased abundances may be second order effects (mediated by reduced competition or predation) of increased fishing pressure. In particular, opposing differences in abundance of predatory triggerfishes (Balistidae) and emperors (Lethrinidae) and of sea urchins are compatible with the view that higher populations of sea urchins may sometimes occur where the densities of their predators are reduced. Overall results allow an assessment of the effect of the artisanal fishery on the fish stocks, and provide a measure of the effectiveness of protection afforded by the marine park.
Habitats and species of Baie Ternay MNP and
TMRU (1996) Habitats and species of Baie Ternay MNP and Baie Beau Vallon, Mahe. Tropical Marine Research Unit, University of York.
Habitats and species of the Malindi and Watamu National Marine Reserve
TMRU (1995) Habitats and species of the Malindi and Watamu National Marine Reserve, Kenya. Tropical Marine Research Unit, University of York.
Report on the distribution of fish species between Kisite Marine National Park and Mpunguti Marine National Reserve
TMRU (1993) Report on the distribution of fish species between Kisite Marine National Park and Mpunguti Marine National Reserve. Tropical Marine Research Unit, University of York.
Habitats and species of the Diani coast
TMRU (1994) Habitats and species of the Diani coast, Kenya. Tropical Marine Research Unit, University of York.
The ecological basis of multispecies fisheries, and management of a demersal fishery in tropical Australia In Fish Population Dynamics eds
  • K J Sainsbury
Sainsbury, K.J. (1988). The ecological basis of multispecies fisheries, and management of a demersal fishery in tropical Australia. In Fish Population Dynamics eds. J.A. Gulland. pp. 349-382. Wiley.
Seychelles Artisanal Fisheries Statistics
  • Sfa
SFA, 1990-1994. Seychelles Artisanal Fisheries Statistics. SFA Technical Report. SFA, P.O. Box 449, Mahe, Seychelles
Ecological research in the coastal lagoons of the Republic of Seychelles
  • A Khadun
Khadun, A. (1991). Ecological research in the coastal lagoons of the Republic of Seychelles. In Workshop on Tropical Coastal Lagoon Ecosystems, Inhaca Island, Mozambique. Dec 3-5, 1991. SAREC DOCUMENT.