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Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
1
Small cetacean captures and CPUE estimates in artisanal
fisheries operating from a port in northern Peru, 2005-2007
Joanna Alfaro Shigueto
1,2
, Jeffrey C. Mangel
1,2
and Koen Van Waerebeek
3
1
Pro Delphinus, Octavio Bernal, 572-5, Lima 11, Peru.
2
University of Exeter, Center for Ecology and Conservation, Penryn, Cornwall, United Kingdom.
Email: joga201@exeter.ac.uk
3
Peruvian Centre for Cetacean Research (CEPEC), Museo de Delfines, Pucusana, Lima 20, Peru.
ABSTRACT
This work provides the first direct, at-sea monitoring of small cetacean interactions with Peruvian artisanal drift gillnet
and longline vessels. A total of 253 small cetaceans were observed captured during 66 fishing trips (480 sets) monitored
from March 2005-July 2007 in the port of Salaverry, northern Peru. Interactions consisted of 231 animals caught in
gillnets, 1 in a longline and 21 direct takes by harpooning for use as bait. The most commonly captured species were
long-beaked common dolphins Delphinus capensis, dusky dolphins Lagenorhynchus obscurus, common bottlenose
dolphins Tursiops truncatus (offshore stock) and Burmeister’s porpoises Phocoena spinipinnis. Overall bycatch CPUE
(catch per unit effort) was estimated to be 0.677 animals/set and 0.007 animals/set for gillnet and longline vessels,
respectively. Based upon total fishing effort for the port, we estimated the average of small cetacean bycatch at 2,623
animals/year (CI 2,061-3,185) for 2002-2007. This work indicates that, in at least one Peruvian port, bycatch and
harpooning of small cetaceans persist at high levels and on a regular basis, particularly in driftnet vessels. The formerly
unknown practice of at-sea discarding of carcasses stands in sharp contrast with current, high small cetacean discard rates
(49%) found in this study. That, combined with high prices/lack of availability of traditional bait fish suggest that small
cetacean bycatch and harpooning could now potentially be reduced through the implementation of bycatch mitigation
measures and greater accessibility to preferred bait.
KEYWORDS: Direct capture, effort, fisheries, gillnets, incidental catches, conservation, catch per unit effort, South
America, Pacific Ocean
INTRODUCTION
International legal measures to ban the take of dolphins and porpoises in fisheries have acted as a protective measure to
reduce declines of cetacean populations. However, cetacean bycatch remains a concern for fisheries worldwide (Lewison
et al., 2004, Read et al., 2006). Moreover, artisanal fisheries may contribute significantly to cetacean mortalities caused
at sea (Read et al., 2006). Gillnet fisheries in particular have been cited as significant causes of small cetacean mortality
(Jefferson and Curry, 1994; Dawson and Slooten, 2005; Read et al., 2006).
In Peru, previous research into small cetacean captures has focused on monitoring of landings of carcasses and
monitoring fishmarkets for presence of small cetacean products (Read et al., 1988; Van Waerebeek and Reyes, 1990,
1994; Van Waerebeek, 1994; Van Waerebeek et al., 1997, 2002a). This long-term monitoring work has been extremely
valuable in documenting the changes in fisheries interactions and in developing estimates of small cetacean captures for
the country, besides collecting much needed natural history data. The species primarily affected included long-beaked
common dolphin Delphinus capensis, dusky dolphin Lagenorhynchus obscurus, Burmeister’s porpoise Phocoena
spinipinnis, and common bottlenose dolphins Tursiops truncatus (both inshore and offshore forms), although low
numbers of at least another ten species were also taken (see Van Waerebeek et al., 1988; Van Waerebeek and Reyes,
1994).
Before ministerial decrees came into force in 1990 and 1994 and, failing, were reinforced by a national law in 1996
(Anonymous, 1996), prohibiting the take, landing and sale of small cetaceans in Peru, the bycatch and directed take could
be monitored in Peruvian fishing ports (reviewed in Van Waerebeek et al., 1994). Indeed, discards were minimal
because of the important commercial value of fresh dolphin meat. When cetaceans gradually disappeared from view in
fishmarkets with the implementation of the ban of small cetacean exploitation, other methods were required to tally
catches. Here we report on recent at-sea observations of artisanal gillnetting and longlining activities allowing direct
estimates of bycatches per unit of effort for artisanal fisheries operating from a Peruvian port.
Captures of small cetaceans were thought to have peaked in the period 1990-1993 when estimates of total takes ranged
between 15,000 and 20,000 animals per annum (Van Waerebeek and Reyes, 1994). However, this legislation is not fully
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
2
enforced and the capture and trade of small cetaceans continues (e.g. Van Waerebeek et al., 2002a, unpublished data;
This paper). Moreover, updated data on numbers of cetaceans caught and the spatial and temporal distribution of
cetaceans and bycatch are essential in defining the scale of this continuing problem and in designing appropriate national
and regional management and conservation measures. The IUCN Cetacean Specialist Group (CSG) and the IWC
Scientific Committee have all at some point listed both the Peruvian dusky dolphin and Burmeister´s porpoise as
priorities for cetacean bycatch reduction. Likewise, the IUCN-CSG noted the need for reliable estimates of fisheries
related mortality of small cetaceans (Reeves et al., 2003, 2005).
Building upon this previous work and in line with recommendations for small cetacean research needs in Peru, the
objective of this project was to assess the effectiveness of the existing ban on the capture and trade of small cetaceans by
placing onboard observers on fishing vessels to directly record and characterize incidental and direct takes of dolphins
and porpoises. The study provides a more direct and thus more accurate estimate of CPUE rates than was possible from
landings and provides insights into aspects of the contrast between the legal requirements of a ban on small cetacean
captures and the realities of virtually unavoidable bycatches and short-sighted local fishing practices.
MATERIALS AND METHODS
At-sea observers
All observers were biologists and were trained in data collection methods and marine mammal identification. Data
sheets, GPS units and all other necessary equipment were provided. Datasheets were designed to gather information on
fishing operation, the vessel specific gear used (longline or gillnet) and the bycatch obtained during the fishing trip.
Biological samples were also collected from many captured small cetaceans. Tissue samples (muscle or skin) were
packed in salt and stored in individual containers for future genetic analysis. Observers were provided with disposable
cameras in order to photograph unusual or unidentifiable captures for later species identification. Common dolphins
Delphinus spp. were not identified to species in the boats, nor were Tursiops truncatus (further referred to as ‘bottlenose
dolphins’) assigned to inshore/offshore morphotype, considering there was a degree of uncertainty about positive
identification among observers. All observer data were managed in a Microsoft Access relational database.
All vessels upon which observers operated were voluntary participants in the project. Observers did not take part in
fishing activity. They worked throughout the year in order to account for changes in target species and to account for any
possible seasonal and spatial variation. Observers monitored both longline and gillnet vessels. Observer effort varied by
month depending on various factors such as the availability of boats and observers, weather conditions and project
funding.
From March 2005 to July 2007 these observers monitored a total of 66 artisanal fishing trips (480 sets) for small cetacean
bycatch. Artisanal fisheries are defined here, according to Peruvian fisheries regulations, as containing boats with a
maximum of 32.6m
3
of storage capacity, 15m of length, and principally based on the use of manual work during fishing
operations (Ley General de Pesca, 2001). Trips monitored were on gillnet and longline vessels originating from the port
of Salaverry (8
o
14’S, 78
o
59’W). Captures of seabirds, sea turtles and pinnipeds were also recorded but are not reported
here. Bycatch per unit effort (CPUE) was calculated as bycatch/set and bycatch/trip. Longline CPUE was also reported
as catch/1000 hooks. Descriptive statistics are presented ± standard deviation (SD) and with 95% confidence intervals
(CI) unless specified otherwise. Statistical tests were performed using SPSS 15.0. All spatial analyses and maps were
prepared using ESRI ArcMap 9.1, MATLAB and Hawth’s Tools (Beyer, 2004). Bathymetry values were determined
with Global Gridded Relief Data (ETOPO2v2) with 2’ minute resolution (USDOC, 2006). Quartic kernal and 90%
probability contour analyses were performed using 2km grid spacing and least squares cross validation derived optimised
smoothing factors for longline (23km) and gillnet (24km) sets and a person selected smoothing factor of 35km for small
cetacean capture locations.
Shore-based observers
Shore based observers were employed in Salaverry to monitor daily fishing activity from September 2001 to March
2008. Observers collected data on the daily number of fishing trips, locations of fishing activity and associated catch and
bycatch. Data collection was based upon interviews with fishermen and monitoring of dockside activity.
Fishermen interviews
In Salaverry from July to October 2006 Pro Delphinus researchers also conducted guided interviews with fishing captains
and crew of gillnet and longline vessels regarding the frequency of small cetacean harpooning and use as bait and reasons
for this practice. Interviews were held at the port over the course of three days with fishermen who agreed to participate.
While not a representative sample of the Salaverry fishery generally, the purpose of the interviews was to provide more
detail on small cetacean interactions than could be obtained solely through the work of onboard observers. Respondents
were asked in ten questions to describe the fishery in which they worked (target species, fishing areas, etc.) as well as
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
3
types of bait used, frequency of small cetacean harpooning, reasons small cetaceans are used as bait, species targeted and
use of small cetaceans as a food source.
RESULTS
Gillnets characteristics
This project monitored 46 trips (342 sets) by artisanal drift gillnet vessels. All monitored trips targeted sharks and rays
(mainly smooth hammerheads Sphyrna zygaena, eagle rays Myliobatis spp., blue sharks Prionace glauca, short-fin
makos Isurus oxyrinchus and thresher sharks Alopias vulpinus). The average duration of trips was 8.2±2.4 days (range:
3-13). The average number of sets per gillnet trip was 7.4±2.4 (range: 2-11). Gear was typically set in the afternoon and
retrieved the following morning. Gillnet sets averaged 14.5±5.0 hours (range: 0.78-38.6). The only reported bait used
was small cetacean blubber or meat (see Results and Discussion). Gillnets observed were made of multifilament nylon
cord. Nets were made of panels averaging 48.3±15.0 fathoms (Range: 30-80 fathoms) in length by 6 to 7m in depth.
Vessels deployed an average of 20.7±4.4 panels (Range: 10-36). Stretched mesh sizes ranged from 4.5 to 10 inches
(11.2 x 25.4cm).
Longline characteristics
A total of 20 trips by artisanal longline vessels (138 sets; 167,670 hooks) were monitored. Sixteen of 20 trips (80%)
targeted dorado Coryphaena hippurus with the remaining 4 trips targeting sharks (mainly blue and shortfin mako). The
average duration of trips was 10.3±2.6 days (range: 5-14). The average number of sets per longline trip was 6.9±2.3
(range: 3-11). Longline sets averaged 9.15±2.6 hours (Range: 2.1-18.7). Gear was typically set in the morning and
recovered the same day in the late afternoon. An average of 1,215±268.5 hooks was deployed per set (Range: 600-
1,650). Mainlines were set at the sea surface. Mainlines were made of multifilament nylon rope. Branchlines were
made of narrow diameter nylon multifilament cord. Leader materials used were either nylon monofilament when
targeting dorado or metal cable when targeting sharks. Average length of branchlines was 3.8±1.9 fathoms (range: 2.5-
10 fathoms). Bait used included jumbo flying squid Dosidicus gigas and small cetacean blubber or meat (see Results and
Discussion).
Summary of small cetacean interactions
A total of 253 dolphins and porpoises were recorded captured during the study period. Eighty percent of gillnet trips (37
of 46 trips) and 5% of longline trips (1 of 20) reported small cetacean bycatch. In addition, 15% of longline trips also
harpooned dolphins for use as bait (Table 1). No fishing trips that targeted dorado reported small cetacean bycatch.
Three quarters of all captured animals were either common dolphins (47%) or dusky dolphins (29%). Captures also
included Burmeister’s porpoises, bottlenose dolphins, Risso’s dolphins Grampus griseus, unidentified small cetaceans
and ‘Cachalotillo’ (which could refer to pilot whales Globicephala spp., Risso’s dolphin or Kogia spp.) (Table 1). A
subsample of available photos examined indicated long-beaked common dolphins D. capensis and no evidence of short-
beaked common dolphins Delphinus delphis. We therefore believe that interactions were largely, if not wholly, with
long-beaked common dolphins.
All entangled dolphins and porpoises were captured in 105 sets during 38 fishing trips undertaken by 18 different vessels.
All but one of these capture events were by gillnet vessels. For sets with dolphin or porpoise captures, the mean number
captured per set was 2.24±1.65 (range: 1 to 9 animals/set, n=105 sets). The average reported water temperature for sets
with captures was 19.1±1.9
o
C (Range: 15 to 25
o
C).
Common dolphins, dusky dolphins and bottlenose dolphins were mainly either discarded dead or used for bait (Table 2).
Of known fate individuals, a majority of bottlenose dolphins and common dolphins were discarded dead. Half of known
fate dusky dolphins were used for bait with the remaining half distributed among the other fate categories. Final fate of
Burmeister’s porpoises differed from the other three common bycatch species with 71.5% reported as either consumed by
the boat crew or brought to shore to be eaten at home.
Four gravid females were entangled in gillnets. These consisted of 2 dusky dolphins (October 2005), 1 Burmeister’s
porpoise (March 2005) and 1 common dolphin (April 2005).
A total of 21 dolphins were harpooned, of which 16 were by longline vessels. These events occurred on 3 trips by 3
different boats and included takes of 8, 6, and 2 individuals. The remaining five animals were killed by gillnet vessels.
The gillnet events also occurred over three trips and three different boats and included takes of 3, 1, and 1 individuals.
Thirty-eight percent of harpooned animals were dusky dolphins (Table 2). All harpooned animals were used for bait.
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
4
Spatial distribution
The unreliability of remote sensing bathymetry data in coastal zones (<200m) makes detailed interpretation of the depths
of captures difficult since most captures were in less than 250m depth (Cracknell, 1999; Malthus and Mumby, 2003).
However, several general patterns do emerge when examining fishing effort and small cetacean capture locations.
Gillnet sets were more coastal than longline sets (Figure 1a) with gillnet trips occurring over the continental shelf and
longline trips occurring on the continental slope or pelagic. All small cetacean interactions appear to take place on the
continental shelf or near the slope. There was a statistically significant difference in perpendicular distance to shore of
captures between the four most commonly taken species (H=52.117, Kruskal-Wallis, P=0.000). Captures of
Burmeister’s porpoises were the most nearshore, occurring in a small area fronting Salaverry and an average of
16.9±15.3km from shore (Range: 3.2-52.5.0km; Figure 1e). Bottlenose dolphin interactions occurred furthest from shore
at an average of 97.8±46.1km (Range: 49.4-191.3km; Figure 1d). Locations of captures of bottlenose dolphins also
indicate that animals were from offshore as opposed to the inshore (coastal) population (sensu Van Waerebeek et al.,
1990; Sanino et al., 2005). There was no significant difference (Z=-0.380, Mann-Whitney, P=0.704) in capture locations
of common (Average=63.2±30.5km; Range: 3.2-170.0km) and dusky dolphins (Average=67.4±35.9km; Range: 10.7-
191.3km), with both species more dispersed throughout the continental shelf (Figure 1a, b).
Fishermen interviews
Twenty-one interviews were conducted over three days in July, September and October of 2006. Nine respondents were
crew members on longline vessels and 12 were from gillnet vessels. Respondents indicated that the preferred bait for
longlines was mackerel Scomber japonicus (47%) or jumbo flying squid (47%). Small cetacean was also listed as a bait
type but was not preferred (6%). For gillnet respondents, 38% indicated that they used small cetaceans as bait. Seventy-
nine percent of gillnet respondents indicated that small cetacean meat was the bait used for catching sharks because of its
high blood and fat content. When asked why they used small cetaceans for bait, 29% reported it was because other bait
was not available and another 14% stated that small cetaceans were inexpensive to buy or harpoon. Sixty-two percent of
respondents indicated that they eat small cetaceans at home. The most frequently captured species reported was the
bottlenose dolphin (50%). When asked if they were interested in stopping the use of small cetaceans as bait 86% agreed.
When asked for possible solutions to the use of small cetaceans as bait, 67% responded that other types of bait must be
found to replace dolphin meat.
CPUE and fishing effort
Gillnets
Gillnet CPUE of small cetaceans was 0.677±1.37 animals/set (CI 0.531-0.824) or 5.02±4.58 animals/trip (CI 3.66-6.38).
These calculations exclude the six dolphins harpooned by gillnet vessels. The overall interaction rate for gillnet vessels
(including entangled and harpooned animals) was 5.13±4.59 animals/trip (CI 3.77-6.49). Bycatch rates per species are
presented in Table 3.
Gillnet entanglements made up 91.3% of small cetacean captures. Ninety-seven percent of gillnet entangled animals
were recovered dead and approximately half (49%) of all gillnet entangled animals were discarded. A large number
(31%) of entangled animals were used for baiting gillnets. Half of all gillnet interactions were with common dolphins
with the remaining half divided among Burmeister’s porpoises, dusky dolphins, bottlenose dolphins, and unidentified
species. Entangled animals were also used for sale in local markets, for consumption in the boat or at home, released
alive or were given to other vessels for use as bait (Table 2).
Longlines
Longline CPUE (which consisted of 1 dusky dolphin) was 0.007±0.080 animals/set or 0.05±0.224 animals/trip, i.e. about
1% of the bycatch rate in gillnets. The dusky dolphin observed had become entangled around its flukes or tail stock and,
while captured alive, was killed and used for bait. This project observed 167,670 hooks and yielded a bycatch estimate
of 0.006 animals/1000 hooks. The overall interaction rate for longline vessels (including bycatch and harpooned
animals) was a relatively high 0.85±0.52 animals/trip due to the common habit of harpooning dolphins for bait.
Salaverry fishing effort
Based upon daily shore based monitoring of fishing effort in Salaverry we calculated that there were an average of
518.2±90.0 gillnet trips (range: 411 to 620 trips/year) and 300.7±25.2 longline trips (range: 272 to 341 trips/year) per
annum, for the years 2002 to 2007.
Knowing total monthly fishing effort and total monthly observer effort for the period March 2005 – July 2007 we were
then able to calculate the percent of fishing trips observed. Observer effort averaged 3.4±2.6% (range: 0-10%) of
monthly gillnet trips (March 2005-July 2007) and 3.7±4.6% (range: 0-17%) of monthly longline trips.
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
5
Based upon our bycatch estimates and the data on the total annual Salaverry fishing effort we are able to estimate the
total number of small cetacean interactions for the gillnet and longline fleets. The average number of sets per observed
gillnet and longline trip were 7.4 and 6.9 respectively. Combining this information with the data on annual total trips we
estimated the total number of sets per year (Tables 3-5). For the years 2002 to 2007 the estimated annual number of
small cetaceans captured in gillnets and longlines in the port of Salaverry was 2,608 (CI 2,046-3,170) and 15 animals,
respectively (Table 4). Based upon the per species bycatch rates calculated (Table 4) we then estimated annual per
species bycatch (Table 5).
DISCUSSION
Small cetacean interactions
Previous work monitoring the take of small cetaceans in Peru’s artisanal fisheries focused largely on dockside monitoring
of landing, monitoring of fishmarkets for small cetacean products and assessing beach cast carcasses for evidence of
fishery interactions (Read et al., 1988; Van Waerebeek and Reyes, 1990, 1994; Van Waerebeek, 1994; Van Waerebeek
et al., 1997, 2002a). The work presented here provides the first direct, at-sea monitoring of small cetacean interactions
with Peruvian artisanal gillnet and longline vessels. It has shown that, in at least one port in northern Peru, bycatch and
harpooning of small cetaceans persist at high levels and on a regular basis, particularly in driftnet vessels, despite the
existence since the mid-1990s of national legislation banning the capture of marine mammals and commerce in their
products. Many opportunistic interviews with fishermen in Pucusana by one of us (KVW) over the past few years
suggest that the situation of continued bycatches and harpoonings, despite much reduced landings, is similar on Peru’s
central coast.
Similar to previous work, we found that small cetacean interactions took the forms of bycatch and harpooning. The four
most common small cetacean bycatch species reported, both then and now, were long-beaked common dolphins, dusky
dolphins, bottlenose dolphins and Burmeister’s porpoises. The most frequently entangled species in the current study
was the common dolphin which made up 50% of gillnet interactions. The dusky dolphin was the second most frequently
captured species with 28% of gillnet interactions.
For 1991-1993 Van Waerebeek (1994) noted a decline in the catch composition proportion of dusky dolphins and an
increase in the proportion of common dolphins (also Van Waerebeek et al., 2002a). The author suggested that the
proportional decline in dusky dolphins captures could be a result of several decades of exploitation by Peruvian fisheries.
The higher proportion of common dolphins found in the current study could be indicative of this continued decline but
may also be due to the fact that the present study occurred at a port near the northern limit of the species’ known range
(Van Waerebeek, 1992a, 1992b).
Van Waerebeek and Reyes (1994) and Van Waerebeek et al. (1997) provide the only previously available description of
small cetacean interactions for the port of Salaverry. Both studies reported that Burmeister’s porpoise was the most
frequently landed species (in 1994, 75% of 73 identified cetaceans), with landings occurring on an almost daily basis. In
the present study, Burmeister’s porpoise was the fourth most commonly captured species at 6% of all captures. Given
the paucity of information on Burmeister’s porpoise abundance, distribution or fishery interactions it is not clear why this
discrepancy in catch frequency may exist but we note that many gillnet sets tended to be further offshore than the narrow
coastal area in which Burmeister’s porpoise bycatch occurred (figure 2d). Usual fishing grounds may have moved
further offshore as the density of fish schools closer to port may have decreased due to high fishing pressure.
The present study also supports previous findings that fishery interactions come in the forms of bycatch and harpooning.
Our results indicate that bycatch of small cetaceans is a much more important cause of mortality than harpooning.
Bycatch occurred in both gillnet and longline vessels and while longline entanglement is almost negligible (1%)
compared to gillnet entanglement, harpooning is more common on longliners. Almost all gillnet bycatch was recovered
dead and approximately half of all entangled small cetaceans were discarded at sea. Thus, while half of carcasses were
used opportunistically as bait or for consumption, the fact that the other half of all bycatch was discarded indicates that
interactions with small cetaceans are often unwanted. This stands in sharp contrast with the 1985-1994 situation when
discards were rare and most carcasses were landed to be sold, openly or covertly (e.g. Van Waerebeek and Reyes, 1994).
This suggests that the promotion and implementation of bycatch avoidance measures in the gillnet fishery may now,
perhaps for the first time, be acceptable to fishermen as a means of reducing unwanted catch.
Clearly though, a demand for small cetacean products in the form of bait and meat persists. Bait was collected from
entangled animals but also from animals harpooned specifically to collect bait. Harpooning for bait occurred on both
gillnet and longline vessels. When used in gillnets, pieces of dolphin blubber and meat were tied to the center of the net
pane, with this being repeated for each pane. Dolphin blubber and meat was the only bait reported used in gillnets during
the study and was used specifically due to its claimed effectiveness in attracting blue and short-fin mako sharks. Use of
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
6
small cetaceans as bait was also reported during interviews with fishermen (both in Salaverry and Pucusana) where they
noted dolphin meat’s particular effectiveness for catching sharks given its high blood and fat content. Previous work also
reported on this usage and warned that increasing demand for small cetacean meat and blubber as shark bait could offset
any reductions in small cetacean take as a result of the ban on capture and commerce (Van Waerebeek et al., 1997; Van
Waerebeek et al., 2002a). The capture of small cetaceans for use as bait has also been reported in coastal communities in
Colombia (Mora-Pinto et al., 1995) and Argentina (Goodall et al., 1994), but the practice is common worldwide.
In discussions with fishermen regarding their use of small cetaceans for bait, a large number indicated that one reason for
the use of dolphins and porpoises was the high cost of traditional bait fishes like mackerel. These fishermen indicated
that they would, in fact, prefer to use their traditional bait. Given that all observed harpooning events in this study were
to collect bait, that preference suggests that if these, or effective alternative, baits could be provided cheaper, then
harpooning of small cetaceans could perhaps largely be avoided.
Small cetaceans were also reported as either consumed by boat crews or brought to shore for consumption at home or
sale in markets. Of the four species, the Burmeister’s porpoise was the most preferred as a food source with 5 of the 7
porpoises for which fate is known, were consumed either by the boat crew or by family at home. Interviews with
fishermen revealed that a majority of respondents eat small cetacean meat at home.
Additional research conducted by Pro Delphinus biologists at fishmarkets in the ports of Salaverry and Chimbote
indicates that small cetacean meat is available on an regular basis and consisted of the same four species documented
here and in previous market studies (Pro Delphinus unpublished data; Van Waerebeek et al., 2002a; Van Waerebeek et
al., 1997; Van Waerebeek and Reyes, 1990, 1994; Read et al., 1988).
CPUE and fishing effort
The four most common small cetacean species involved in bycatch are distributed along most of the Peruvian coast
where they overlap with artisanal fishing activity. Dusky dolphins and Burmeister’s porpoises have been encountered
along the entire Peruvian coast up to Salaverry and Bahia de Paita (05
o
01’S) respectively (Reyes and Van Waerebeek,
1995; Van Waerebeek et al., 1997, 2002b). Inshore bottlenose dolphins are documented along most of Peru’s coast and
offshore bottlenose dolphins are thought to form a continuous distribution from southern Ecuador to at least central Chile
(Van Waerebeek et al., 1990; Sanino et al., 2004). Delphinus spp. are also distributed along the entire Peruvian coast
(Van Waerebeek et al., 1988, 1994). Data from two research cruises (respectively from 4
o
-12
o
S and from 3
o
-18
o
S) to
100-150nm offshore, conducted by Peru’s marine research agency IMARPE in 1998, indicated that common dolphins,
dusky dolphins and bottlenose dolphins were the most commonly encountered small cetaceans from approximately 5
o
S to
18
o
S (Sánchez et al., 1998; Sánchez and Arias-Schreiber, 1998).
Also distributed along the entire Peru coast are the 122 ports and landing sites used by the artisanal fishery. A survey of
the artisanal fleet conducted in 2004-2005 found that there were 9,667 artisanal vessels operating in Peru (Estrella, 2007).
This represents a 54% increase in the size of the artisanal fleet from 1996-1997 (Escudero-Herrera, 1997). Longline
vessels increased from 3.5% of the fleet in 1996-1997 to 9.8% of the fleet in 2004-2005. The number of longline trips
also showed an increase and for the second half of 1999, 1,968 longline trips were recorded (Estrella et al., 2000). For
the entire year of 2002, 11,316 trips were conducted (IMARPE, unpublished data). This suggests substantial growth in
the longline fishery since 1999. The increase in the size of the longline fleet came in part due to efforts in the 1990s to
promote longlining as a means to reduce small cetacean interactions in artisanal fisheries (Reyes, 1993). However, even
though the percentage of gillnet vessels in the fleet declined from 1996-1997 to 2004-2005, the absolute number of
vessels increased from 2,520 to 3,190. Gillnets were the most frequently used fishing methods reported in both studies.
During 1999, 63,083 gillnet trips were conducted (Estrella et al., 1999, 2000).
Given the high rates of small cetacean interactions reported here for one port (an estimated average annual take of 2,608
animals in gillnets for the years 2002-2007) and the distribution of small cetaceans along the coast overlapping with the
large number of artisanal fishing trips, it is feasible that, at the national level, interactions between artisanal fisheries and
small cetaceans remain very substantial. Indeed, it is possible that total mortality by the artisanal fishery is on the order
of that which was occurring in 1990-1993 when there was an estimated take of 15,000-20,000 small cetaceans annually
for all of Peru including captures by industrial purse-seiners (Van Waerebeek and Reyes, 1994), prior to the
implementation of the ban on captures in the mid-1990s. We believe, however, that the CPUE estimate for longline
bycatch obtained in this study may be an overestimate. For example, onboard observer monitoring of 193 longline trips
(1,324 sets) from the port of Ilo in southern Peru by Pro Delphinus observers documented a bycatch of one small
cetacean. In addition, harpooning has not been observed (Pro Delphinus unpublished data). The overall interaction rate
for longline vessels remains relatively high though, given the frequency of harpooning off Salaverry.
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
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It is possible, but unlikely given historical perspectives, that results presented here for Salaverry are not representative of
interaction rates for the rest of Peru. However, we note that a study based upon monitoring of 15 artisanal landing sites
in 1999-2001 in northern and central Peru reported that small cetacean landings were still commonplace (Van Waerebeek
et al., 2002a). It is also in central and northern Peru where gillnet activity is greatest due to the greater width of the
continental shelf in comparison with the south of the country. Results of recent market sampling conducted in the port of
Chimbote in 2006-2007 indicated that small cetacean meat was available on a regular basis (Pro Delphinus unpublished
data). Given the size of the artisanal and industrial fleets operating out of Chimbote, it is likely that small cetacean
products originated there as opposed to being transported from Salaverry. Furthermore, genetic analyses of Burmeister’s
porpoises captured in the ports of Salaverry and Chimbote found a weak but significant nuclear DNA differentiation
between the two harbours (Rosa et al., 2005). One proposed explanation for this result was that fishing vessels from the
two ports were using distinct fishing grounds.
Future directions
This research makes clear that small cetacean bycatch and direct take continues despite the existence of national
legislation prohibiting capture and commerce in their products. We believe these results show the need for renewed
interest on the part of all stakeholders to expand the scope of research and monitoring of small cetacean populations and
their interactions with Peru’s artisanal fleet. This study demonstrates the feasibility and use of independent observer
programmes onboard artisanal fishing boats, and we strongly recommend that such surveys be continued and expanded.
Priority should be given to increased monitoring of gillnet fisheries in the center and north of the country where the fleet
is concentrated. Given the large number of ports and landing sites used by the artisanal fleet it may be more practicable
to choose a number of ‘index’ ports distributed along the coast and to focus on maximizing onboard observer coverage in
these locations. Babcock et al. (2003) recommended 20% observer coverage for creation of accurate estimates for
common species and 50% for rare species. Observer effort should optimally be continuous in order to account for any
temporal variations in interactions, or should at least ensure an adequate coverage of all seasons. Special attention should
be paid to interactions with dusky dolphins and Burmeister’s porpoises since previous research indicate that the Peruvian
populations of these species form reproductively and genetically isolated stocks that should be subject to stock specific
management measures (Van Waerebeek, 1992a, 1993; Cassens et al., 2003, 2005; Rosa et al., 2005). The population
status of long-beaked dolphins off Peru is unknown but is currently under study.
While large, the artisanal fishery is one of several fisheries operating in Peruvian waters and potentially interacting with
small cetaceans. One must also consider interactions with other fisheries, most notably industrial purse-seine vessels
targeting small schooling fish, especially anchovy. Based upon onboard observer effort of 2% of the fleet in 2002, van
Oordt and Alza (2006) reported an average capture rate of 0.041 dolphins/set. They noted that small cetacean captures in
the fishery could be significant given the estimated 80,000 fishing trips per year. Data on fishing effort for all fisheries
operating in Peru’s coastal waters need to be compiled in order to have a clear understanding of the overall impacts on
small cetacean populations.
Two promising findings stand out from this research. First, it is apparent, given the high discard rates observed, that
small cetacean bycatch was often undesirable or unusable. Fishermen may therefore be open to using mitigation methods
to reduce small cetacean bycatch. Closure of fishing areas to gillnetting or modification of gillnets (Dawson, 1991) seem
hardly implementable in Peru. The use of acoustic alarms has been shown to reduce gillnet bycatch in some dolphin and
porpoise populations (Kraus et al., 1997; Kastelein et al., 2001; Cox et al., 2003; Barlow and Cameron 2003; Koschinski
et al., 2006; Leeney et al., 2007). Acoustic alarms should also be trialed in the Peru gillnet fishery. Second, discussions
with fishermen indicated that small cetacean meat and blubber was used as bait in part due to the high cost of traditional
bait Finding an appropriate, low-cost substitute bait to cetacean meat and blubber could reduce harpooning in both the
longline and gillnet fleets and could further promote the use of bycatch mitigation measures by gillnet vessels.
ACKNOWLEDGEMENTS
Pro Delphinus (JAS, JCM) research on cetacean bycatch has received funding from the Oak Foundation though Duke
University, Rufford Foundation, Whale and Dolphin Conservation Society, Cetacean Society International and Cleveland
Metroparks Zoo. CEPEC (KVW) research on cetacean bycatch has benefitted from long-term IFAW support. Van
Waerebeek attends the IWC/60 SC meeting as head of scientific delegation for the Federal Public Service, Public health,
Food Chain security and Environment, Brussels, Belgium. We sincerely thank Dr. Brendan Godley for his assistance
and comments developing the manuscript, Dr. Matthew Witt for assistance with spatial analyses and Mariela Pajuelo and
Celia Caceres for their vital contributions implementing the observer program. JAS and JCM are ORSAS and Exeter
University scholarship awardees.
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
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REFERENCES
Anonymous. 1996. Ley 26585. Declaran a delfines y otros mamiferos marinos como especies legalmente protegidas.
Diario El Peruano, Normas Legales, Lima, 9 de Abril de 1996: 138665.
Babcock, E.A., Pikitch, E.K. and Hudson, C.G. 2003. How much observer coverage is enough to adequately estimate
bycatch? Report to the Pew Institute for Ocean Science and Oceana. 36pp. [Available at http://www.oceana.org]
Barlow, J. and Cameron, G.A. 2003. Field experiments show that acoustic pingers reduce marine mammal bycatch in the
California drift gill net fishery. Mar. Mamm. Sci. 19(2): 265-283.
Beyer, H.L. 2004. Hawth’s Analysis tools for ArcGIS. [Available at http://www.spatialecology.com/htools]
Cassens, I., Van Waerebeek, K., Best, B., Crespo, E.A., Reyes, J. and Milinkovitch, M.C. 2003. The phylogeny of
dusky dolphins (Lagenorhynchus obscurus): A critical examination of network methods and rooting procedures. Mol.
Ecol. 12: 1781-1792.
Cassens, I., Van Waerebeek, K., Best, P.B., Tzika, A., van Helden, A., Crespo, E.A., Milinkovitch, M.C. 2005. Evidence
for male dispersal along the coasts but no migration in pelagic waters in dusky dolphins (Lagenorhynchus obscurus).
Molecular Ecology 14: 107-121.
Cox, T.M., Read, A.J., Swanner, D., Urian, K.and Waples, D. 2003. Behavioural response of bottlenose dolphins,
Tursiops truncatus, to gillnets and acoustic alarms. Biol. Conserv. 115: 203-212.
Cracknell, A.P. 1999. Remote sensing techniques in estuaries and coastal zones an update. Int. J. Remote Sens. 20(3):
485-496.
Dawson, S.M. 1991. Modifying gillnets to reduce entanglement of cetaceans. Mar.Mamm. Sci. 7(3):274–282.
Dawson, S.M. and Slooten, E. 2005. Management of gillnet bycatch of cetaceans in New Zealand. J. Cetacean Res.
Manage. 7(1): 59-64.
Escudero-Herrera, L. 1997. Encuesta structural de la pesquería artisanal del litoral Peruano. Inf. Prog. Inst. Mar Perú
59(Junio). 87pp.
Estrella, C., Guevara-Carrasco, R., Avila, W., Palacios, J. and Medina, A. 1999. Informe estadístico de los recursos
hidrobiológicos de la pesca artisanal por species, artes, meses y caletas durante el primer semester de 1999. Inf. Inst.
Mar Perú 148: 1-214.
Estrella, C., Guevara-Carrasco, R., Avila, W., Palacios, J. and Medina, A. 2000. Statistic report on hydrobiological
resources of artisanal fishery, by species, arts, ports, coves and months during the second semester 1999. Inf. Inst. Mar
Perú 151: 1-194.
Estrella, C. 2007. Resultados generals de la segunda encuesta structural de la pesquería artisanal en el litoral Peruano: II
ENEPA 2004-2005 (unpublished). 8pp. [Available from Instituto del Mar del Peru IMARPE]
Goodall, R.N.P., Schiavini, A.C.M. and Fermani, C. 1994. Net fisheries and net mortality of small cetaceans off Tierra
del Fuego, Argentina. Rep. Int. Whal. Commn (Special Issue 15): 295-304.
Jefferson, T.A. and Curry, B.E. 1994. A global review of porpoise (Cetacea: Phocoenidae) mortality in gillnets. Biol.
Conserv. 67: 167-183.
Kastelein, R.A., de Haan, D., Vaughan, N., Staal, C., Schooneman, N.M. 2001. The influence of three acoustic alarms
on the behavior of harbor porpoises (Phocoena phocoena) in a floating pen. Mar. Environ. Res. 52: 351-371.
Koschinksi, S., Culik,B.M., Trippel, E.A. and Ginzkey, L. 2006. Behavioral reactions of free ranging harbor porpoises
Phocoena phocoena encountering standard nylon and BaSO
4
mesh gillnets and warning sound. Mar. Ecol. Prog. Ser.
313: 285-294.
Kraus, S.D., Read, A.J., Solow, A., Baldwin, K., Spradlin, Anderson, E. and Williamson, J. 1997. Acoustic alarms
reduce porpoise mortality. Nature 388: 525.
Leeney, R.H., Berrow, S., McGrath, D., O’Brien, J., Cosgrove, R. and Godley, B. 2007. Effects of pingers on the
behavior of bottlenose dolphins. J. Mar. Biol. Ass. U.K. 87: 129-133.
Lewison, R.L., Crowder, L., Read, A.J. and Freeman, S. 2004. Understanding impacts of fisheries bycatch on marine
megafauna. Trends Ecol. Evol. 19(11): 598-604.
Ley General de Pesca. 2001. Reglamento de la ley general de pesca. Decreto Supremo #012-2001-PE. Titulo 3,
Capitulo 2, Articulo 30.
Malthus, T.J. and Mumby, P.J. 2003. Remote sensing of the coastal zone: An overview and priorities for future
research. Int. J. Remote Sens. 24(13): 2805-2815.
Mora-Pinto, D.M., Muñoz-Hincapié, M.F., Mignucci-Giannoni, A.A. and Acero-Pizarro, A. 1995. Marine mammal
mortality and strandings along the Pacific coast of Columbia. Rep Int. Whal. Commn. 45: 427-429.
Read, A., Van Waerebeek, K., Reyes, J., Mckinnon, J.S., Lehman, L.C. 1988. The exploitation of small cetaceans in
coastal Peru. Biol. Conserv. 46: 53-70.
Read, A.J., Drinker, P. and Northridge, S. 2006. Bycatch of marine mammals in U.S. and global fisheries. Conserv.
Biol. 20(1): 163-169.
Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciara, G. (compilers). 2003. Dolphins, Whales and
Porpoises: 2002–2010 Conservation Action Plan for the World’s Cetaceans. IUCN/SSC Cetacean Specialist Group.
IUCN, Gland, Switzerland and Cambridge, UK. ix + 139pp.
Small cetacean captures and CPUE in northern Peru.
IWC Scientific Committee Meeting, Santiago, June 2008
SC/60/SM19
9
Reeves R.R., Berggren, P., Crespo E.A., Gales, N., Northridge, S.P., Notarbartolo di Sciara, G., Perrin, W.F., Read, A.J.,
Rogan, E., Smith, B.D. and Van Waerebeek, K. 2005. Global priorities for reduction of cetacean bycatch. Report to
the World Wide Fund for Nature. 29pp. [Available at http://panda.org/news_facts/publications/]
Reyes, J.C. 1993. Re-introduction of longlines in the Peruvian shark fishery: An alternative to reduce small cetacean
mortality. Final report presented to the Cetacean Specialist Group IUCN and the Whale and Dolphin Conservation
Society, Lima, Peru.
Reyes J.C. and K Van Waerebeek. 1995. Aspects of the Biology of Burmeister's porpoise from Peru. Rep. Int. Whal.
Commn. (special Issue) 16: 349-364.
Rosa, S., Milinkovitch, M.C., Van Waerebeek, K., Berck, J., Oporto, J., Alfaro-Shigueto, J., Van Bressem, M.F.,
Goodall, N. and Cassens, I. 2005. Population structure of nuclear and mitochondrial DNA variation among South
American Burmeister’s porpoises (Phocoena spinipinnis). Conserv. Genet. 6: 431-443.
Sanino, G.P., Van Waerebeek, K., Van Bressem, M.-F. and Pastene, L.A. 2005. A preliminary note on population
structure in eastern South Pacific common bottlenose dolphins, Tursiops truncatus. J. Cetacean Res. Manage. 7(1):
65-70.
Sánchez, R., Arias-Schreiber, M. and Ontón, K. 1998. Sightings of cetacean in Peruvian sea and its relation with the
main pelagic resources. Cruise RV Humboldt 9803-05. Inf. Mar. Peru 135: 163-179.
Sánchez, R. and Arias-Schreiber, M. 1998. Cetacean sightings on the Peruvian sea and their relation with the
distribution and abundance of pelagic fishes. Cruise RV Humboldt 9808-09, from Paita to Callao. Inf. Mar. Peru 141:
55-66.
USDOC. 2006. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National
Geophysical Data Center. 2-minute Gridded Global Relief Data (ETOPO2v2)
http://www.ngdc.noaa.gov/mgg/fliers/06mgg01.html
van Oordt, F. and Alza, L. 2006. Small cetacean interactions with the purse seine fisheries off the Peruvian coast during
2002. Poster HCS201 presented to the International Conference on the Humboldt Current System: Climate, ocean
dynamics, ecosystem processes and fisheries. Lima, Peru, 27 November-1 December (unpublished). [Available at
http://www.peru.ird.fr/humboldt_speechs/Book_of_Abstracts_total_100107.pdf]
Van Waerebeek, K. 1992a. Population identity and general biology of the dusky dolphin, Lagenorhynchus obscurus
(Gray 1828) in the Southeast Pacific. Ph.D. Thesis, Institute for Taxonomic Zoology, University of Amsterdam.
160pp.
Van Waerebeek, K. 1992b. Records of dusky dolphins Lagenorhynchus obscurus, (Gray 1828) in the eastern South
Pacific. Beaufortia 43(4): 45-61.
Van Waerebeek, K. 1993. Geographic variation and sexual dimorphism in the skull of the dusky dolphin
Lagenorhynchus obscurus (Gray 1828). Fishery Bulletin 91: 754-774.
Van Waerebeek, K. 1994. A note on the status of the dusky dolphins (Lagenorhynchus obscurus) off Peru. Rep. Int.
Whal. Commn.(special issue) 15: 525-527.
Van Waerebeek, K. and Reyes, J. 1990. Catch of small cetaceans at Pucusana port, central Peru, during 1987. Biol.
Conserv. 51: 15-22.
Van Waerebeek, K. and Reyes, J. 1994. Post-ban small cetacean takes off Peru: A review. Rep. Int. Whal. Commn.
(special issue) 15: 503-519.
Van Waerebeek, K., Reyes, J.C., Luscombe, B.A. 1988. Revisión de la distribución de pequeños cetáceos frente al Perú.
pp. 345-51. In: H. Salzwedel, A. Landa (eds.). Recursos y Dinámica del Ecosistema de Afloramiento Peruano. Boletín
del Instituto del Mar del Perú, Callao, Vol. extraordinario.
Van Waerebeek, K., Reyes, J., Read, A.J. and Mckinnon, J.S. 1990. Preliminary observations of bottlenose dolphins
from the Pacific coast of South America. pp. 143-154. In: S. Leatherwood and R.R. Reeves (eds.) The Bottlenose
Dolphin. Academic Press Inc., San Diego. 651pp.
Van Waerebeek, K., Van Bressem, M.F., Reyes, J.C., Alfaro, J.A., Bello, R., Echegaray, M., García-Godos, A. and
Ontón, K. 1994. Illegal exploitation of small cetaceans in Peru. Final report (January 1994) to United Nations
Environment Programme, Nairobi, and Whale and Dolphin Conservation Society, UK. 76pp.
Van Waerebeek, K., Van Bressem, M.F., Félix, F., Alfaro-Shigueto, J., Garcia-Godos, A., Chávez-Lisambart, L., Ontón,
K., Montes, D. and Bello, R. 1997. Mortality of dolphins and porpoises in coastal fisheries off Peru and southern
Ecuador in 1994. Biol. Conserv. 81: 43-49.
Van Waerebeek, K., Alfaro-Shigueto, J., Montes, D., Onton, K., Santillan, L., Van Bressem, M.F. and Vega, D. 2002a.
Fisheries related mortality of small cetaceans in neritic waters of Peru in 1999-2001. Document SC/54/SM10
presented to International Whaling Commission, Shimonoseki, Japan, May. 5pp.
Van Waerebeek, K., Santillan, L. and Reyes, J. 2002b. An unusually large aggregation of Burmeister’s porpoise
Phocoena spinipinnis off Peru, with a review of sightings from the eastern South Pacific. Noticiario Mensual 350: 12-
17.
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Table 1. Small cetacean species composition and capture methods of all observed fisheries interactions
(% in parentheses), March 2005-July 2007.
Species captured
n (%)
Net
Entangle
d
Longline
entangle
d
Harpooned*
Common dolphin 120 (47) 116 (50) 0 4 (19)
Dusky dolphin 73 (29) 64 (28) 1 (100) 8 (38)
Bottlenose dolphin 33 (13) 30 (13) 0 3 (14)
Burmeister’s porpoise 16 (6) 16 (7) 0 0
Unidentified cetacean 8 (3) 2 (1) 0 6 (29)
‘Cachalotillo’ 2 (1) 2 (1) 0 0
Risso’s dolphin 1 (0.4) 1 (0.4) 0 0
Total 253 231 (91.3) 1 (0.4) 21 (8.3)
*16 animals harpooned by longline vessels, 5 by gillnet vessels.
Table 3. Gillnet bycatch rates (catch/set) of the four most commonly captured species.
Species mean CI
Common dolphin 0.340 0.236 - 0.444
Dusky dolphin 0.188 0.097 - 0.278
Bottlenose dolphin 0.088 0.040 - 0.136
Burmeister’s porpoise 0.047 0.015 - 0.079
Table 4. Estimated annual small cetacean bycatch by gillnet and longline vessels for the port of Salaverry.
Gillnets Longlines
Year
#
trips
Estimated
# sets
estimated
captures (CI)
#
Trips
Estimated
# sets
estimated
captures*
2002 411 3,054 2,069 (1,623-2,514) 319 2,201 15
2003 620 4,607 3,121 (2,448-3,793) 289 1,994 14
2004 421 3,128 2,119 (1,663-2,575) 341 2,353 16
2005 572 4.250 2,879 (2,259-3,499) 298 2,056 14
2006 593 4,406 2,985 (2,342-3,628) 285 1,967 14
2007 492 3,656 2,477 (1,943-3,010) 272 1,877 13
Average 518 3,850 2,608 (2,046-3,170) 301 2,075 15
*95% CI not presented for longline captures because it is considered unreliable given only 1 bycatch event.
Table 5. Estimated annual catch of the four most common bycatch species by gillnet vessels
for 2002-2007, mean (CI). Most (if not all) common dolphins are D. capensis.
Year
Common
dolphin
Dusky
dolphin
Bottlenose
dolphin
Burmeister’s
porpoise
2002 1,039 (772-1,356) 573 (296-850) 269 (122-416) 143 (45-242)
2003 1,567 (1,089-2,045) 865 (447-1,282) 405 (184-627) 216 (67-365)
2004 1,064 (740-1,389) 587 (304-870) 275 (125-426) 147 (46-248)
2005 1,446 (1,005-1,887) 798 (413-1,183) 374 (169-578) 199 (62-337)
2006 1,499 (1,042-1,956) 827 (428-1,226) 388 (176-600) 207 (64-349)
2007 1,244 (864-1,623) 686 (355-1,017) 322 (146-498) 172 (53-290)
Small cetacean captures and CPUE in northern Peru.
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Table 2. Species composition, capture methods and use of small cetacean carcasses of all interactions (longline & gillnet, bycatch & harpoon), March 2005-July 2007.
# harpooned for bait
# bycaptured
Species
captured
Total
n
%
Male
Longline
Gillnet
%
Male
Discarded
Dead
For
net
bait
For
longline
bait
For
sale
To
eat at
home
To
eat
in
boat
Released
alive
Given
to
other
boat
Unspecified
Common dolphin 120 66.7 2 2 63.6 58 17 4 10 5 0 1 0 21
Dusky dolphin 73 62.5 8 0 43.8 15 28 3 4 1 1 1 2 7
Bottlenose dolphin 33 0.0 0 3 47.1 17 13 0 0 0 0 1 0 2
Burmeister’s porpoise 16 - 0 0 66.7 1 1 0 0 3 2 0 0 9
Unidentified 8 - 6 0 - 0 0 0 0 0 0 0 0 2
“Cachalotillo” 2 - 0 0 0 0 0 0 0 0 0 0 0 2
Risso’s dolphin 1 - 0 0 - 1 0 0 0 0 0 0 0 0
Total 253 50.0 16 5 55.5 92 59 7 14 9 3 3 2 43
Small cetacean captures and CPUE in northern Peru.
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Figure 1. Locations of all monitored sets by vessel type (a) and set locations of all captures of the four most common bycatch species (b-f). Also presented in each pane
are 90% probability contours of fishing sets and gillnet bycatch (250m, 750m, 2,000m and 3,000m isobaths are indicated).
(a) All fishing sets (b) All gillnet captures (c) Common dolphin
Small cetacean captures and CPUE in northern Peru.
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(d) Dusky dolphin (e) Bottlenose dolphin (f) Burmeister’s porpoise
