Shark Depredation and Unwanted Bycatch in Pelagic Longline
Shark Depredation and Unwanted Bycatch in Pelagic Longline
Shark Depredation and Unwanted Bycatch in Pelagic Longline
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<strong>Shark</strong> <strong>Depredation</strong> <strong>and</strong> <strong>Unwanted</strong> <strong>Bycatch</strong> <strong>in</strong> <strong>Pelagic</strong> Longl<strong>in</strong>e Fisheries<br />
<strong>and</strong> threshers) for which there is sufficient value for their meat.<br />
Furthermore, many operators <strong>in</strong> this fishery will only reta<strong>in</strong> a shark<br />
that is of a marketable species if it is dead or dy<strong>in</strong>g when hauled to the<br />
vessel, which can be safely <strong>and</strong> relatively easily l<strong>and</strong>ed.<br />
The South Africa longl<strong>in</strong>e tuna <strong>and</strong> swordfish fishery is subject to<br />
a shark l<strong>and</strong><strong>in</strong>g limit of 10% of the total swordfish <strong>and</strong> tuna catch.<br />
This theoretically has been economically detrimental to the <strong>in</strong>dustry.<br />
From 1998-2005, the total number of caught sharks was 18% of the<br />
total number of caught swordfish <strong>and</strong> tunas. Thus, vessels would<br />
need to discard about 44% of their caught sharks to comply with<br />
the shark limit. Because only about 18% of caught blue sharks <strong>and</strong><br />
10% of makos have been observed to be released alive <strong>in</strong> this fishery,<br />
<strong>and</strong> the literature demonstrates that a much larger proportion of<br />
these shark species (>85%) are likely alive when hauled to the vessel<br />
(e.g., Beerkircher et al., 2002), it is likely that fishers are not comply<strong>in</strong>g<br />
with this measure.<br />
A prohibition on the use of a wire trace <strong>in</strong> the Australian longl<strong>in</strong>e<br />
tuna <strong>and</strong> billfish fishery <strong>and</strong> South Africa longl<strong>in</strong>e tuna <strong>and</strong> swordfish<br />
fishery has likely resulted <strong>in</strong> an <strong>in</strong>creased economic cost from shark<br />
<strong>in</strong>teractions as this has likely caused an <strong>in</strong>crease <strong>in</strong> the loss of term<strong>in</strong>al<br />
tackle to sharks. A substantially larger number of hooks, bait <strong>and</strong><br />
l<strong>in</strong>e are likely now bitten off of branch l<strong>in</strong>es compared to when wire<br />
trace was used. However, fishers generally do not consider this to<br />
be a large concern. It is not known how the <strong>in</strong>jury to sharks from<br />
reta<strong>in</strong><strong>in</strong>g hook <strong>and</strong> trail<strong>in</strong>g monofilament l<strong>in</strong>e affects their survival<br />
prospects. This is a research priority. This may be an improvement to<br />
their previous fate when caught on l<strong>in</strong>es with wire trace when they<br />
would soak on the gear for hours, be gaffed <strong>and</strong> hauled onboard the<br />
vessel <strong>and</strong> then have hooks removed by cutt<strong>in</strong>g with a knife or pulled<br />
out by force. Available but limited <strong>in</strong>formation <strong>in</strong>dicates that a large<br />
proportion of sharks caught <strong>in</strong> longl<strong>in</strong>e gear that are released after<br />
removal of the hook will survive (Section 6.2.4; U.S. National Mar<strong>in</strong>e<br />
Fisheries Service, 2005). In fisheries where a large proportion of caught<br />
sharks is killed either for retention or discard<strong>in</strong>g, prohibit<strong>in</strong>g the use<br />
of wire leaders will almost def<strong>in</strong>itely reduce shark fish<strong>in</strong>g mortality.<br />
Prohibit<strong>in</strong>g wire leaders may exacerbate seabird bycatch problems:<br />
Fishers will be less likely to attach weights close to hooks on branch<br />
l<strong>in</strong>es lack<strong>in</strong>g a wire leader due to safety concerns, thus, reduc<strong>in</strong>g the<br />
baited hook s<strong>in</strong>k rate, <strong>and</strong> <strong>in</strong>creas<strong>in</strong>g seabird catch rates.<br />
<strong>Shark</strong> fisheries <strong>in</strong> Peru are regulated by the M<strong>in</strong>istry of Fishery<br />
through size limits for certa<strong>in</strong> elasmobranch species (Diario Oficial<br />
El Peruano, 2001). However, there is little enforcement of these<br />
regulations <strong>and</strong> few fishers are aware that the regulations exist<br />
(Alfaro <strong>and</strong> Mangel, 2002). Of the few <strong>in</strong>terviewed fishers who<br />
reported that they were aware of the regulations (5%), all report that<br />
they still reta<strong>in</strong> sharks that are under the m<strong>in</strong>imum size limit.<br />
4.2. International Initiatives Address<strong>in</strong>g <strong>Shark</strong> F<strong>in</strong>n<strong>in</strong>g<br />
There have been several recent <strong>in</strong>ternational <strong>in</strong>itiatives address<strong>in</strong>g<br />
shark f<strong>in</strong>n<strong>in</strong>g. Fisheries subject to restrictions on f<strong>in</strong>n<strong>in</strong>g sharks<br />
are expected to have a high <strong>in</strong>centive to avoid shark <strong>in</strong>teractions.<br />
A summary of <strong>in</strong>ternational <strong>in</strong>itiatives related to shark f<strong>in</strong>n<strong>in</strong>g follows.<br />
• Food <strong>and</strong> Agriculture Organization of the United Nations:<br />
In 1999 the Food <strong>and</strong> Agriculture Organization of the United<br />
Nations (FAO) endorsed the International Plan of Action for the<br />
Conservation <strong>and</strong> Management of <strong>Shark</strong>s. This is a non-legally<br />
b<strong>in</strong>d<strong>in</strong>g voluntary <strong>in</strong>itiative call<strong>in</strong>g on States to ensure the<br />
conservation <strong>and</strong> management of sharks, <strong>in</strong>clud<strong>in</strong>g by m<strong>in</strong>imiz<strong>in</strong>g<br />
waste <strong>and</strong> discards from shark catches such as through requir<strong>in</strong>g<br />
the retention of sharks from which f<strong>in</strong>s are removed (FAO, 1999b).<br />
• International Commission for the Conservation of Atlantic<br />
Tunas: In November 2004, the International Commission<br />
for the Conservation of Atlantic Tunas (ICCAT) adopted<br />
with consensus a b<strong>in</strong>d<strong>in</strong>g measure requir<strong>in</strong>g full utilization<br />
of shark catches (fishers must reta<strong>in</strong> all parts of the shark<br />
except the head, guts, <strong>and</strong> sk<strong>in</strong>s to the po<strong>in</strong>t of first l<strong>and</strong><strong>in</strong>g)<br />
<strong>and</strong> prohibit<strong>in</strong>g vessels <strong>in</strong> ICCAT fisheries from reta<strong>in</strong><strong>in</strong>g on<br />
board, transshipp<strong>in</strong>g, or l<strong>and</strong><strong>in</strong>g any shark f<strong>in</strong>s that are taken <strong>in</strong><br />
contravention of the measure. Countries must ensure that their<br />
vessels reta<strong>in</strong> f<strong>in</strong>s total<strong>in</strong>g no more than 5 percent of the weight<br />
of sharks onboard up to the first po<strong>in</strong>t of l<strong>and</strong><strong>in</strong>g, or otherwise<br />
must ensure compliance with the ratio through certification,<br />
monitor<strong>in</strong>g, or other means.<br />
• United Nations General Assembly: In November 2004, the<br />
United Nations General Assembly adopted by consensus a<br />
resolution on Oceans <strong>and</strong> the Law of the Sea Susta<strong>in</strong>able Fisheries,<br />
<strong>in</strong>clud<strong>in</strong>g through the 1995 Agreement, which <strong>in</strong>cludes a provision<br />
that discourages shark f<strong>in</strong>n<strong>in</strong>g, calls for implementation of the<br />
FAO International Plan of Action on sharks, <strong>and</strong> <strong>in</strong>vites FAO<br />
to study the impact on shark populations of shark catches from<br />
directed <strong>and</strong> non-directed fisheries.<br />
• International Union for Conservation of Nature <strong>and</strong> Natural<br />
Resources: In November 2004, the International Union for<br />
Conservation of Nature <strong>and</strong> Natural Resources (IUCN) adopted<br />
a recommendation urg<strong>in</strong>g all States to ban shark f<strong>in</strong>n<strong>in</strong>g <strong>and</strong><br />
require shark f<strong>in</strong>s to be l<strong>and</strong>ed attached to their bodies.<br />
• Inter-American Tropical Tuna Commission: In June 2005,<br />
the Inter-American Tropical Tuna Commission (IATTC)<br />
adopted a Resolution on the Conservation of <strong>Shark</strong>s Caught <strong>in</strong><br />
Association with Fisheries <strong>in</strong> the Eastern Pacific Ocean, which<br />
bans shark f<strong>in</strong>n<strong>in</strong>g <strong>and</strong> m<strong>and</strong>ates the collection of <strong>in</strong>formation<br />
<strong>and</strong> advice on stock status of shark species. The resolution also<br />
requires members to comply with the FAO International Plan of<br />
Action on sharks <strong>and</strong> take measures to require that their fishers<br />
fully utilize any reta<strong>in</strong>ed sharks.<br />
• North Atlantic Fisheries Organization: In September 2005,<br />
the North Atlantic Fisheries Organization (NAFO) adopted<br />
a resolution modeled after the IATTC <strong>and</strong> ICCAT measures,<br />
bann<strong>in</strong>g shark f<strong>in</strong>n<strong>in</strong>g <strong>in</strong> all NAFO-managed fisheries, <strong>and</strong><br />
m<strong>and</strong>ated the collection of <strong>in</strong>formation on shark catches.<br />
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