The IUCN/SSC Shark Specialist Group
Shark News 4: July 1995
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News
Shark by-catch in longline and gillnet
fisheries operating from the south of Spain
A paper recently submitted to the Fishery Bulletin (V. Buencuerpo,
S. Rios and J. Moron) gives some interesting figures on the importance
of shark by-catch in swordfish fisheries in the eastern North Atlantic
and Mediterranean Sea. Of 51,205 fish sampled in landings during
12 months from July 1991,40,198 were sharks, 9,990 were swordfish
and the rest other bony fish. A large number of immature sharks were
taken. The paper also presents information about the population
structure of shark species and suggests patterns of shortfin mako
movements from catch data.
The authors suggest that the shortfin mako could be the species
most seriously affected by this fishing pressure, although the blue
shark is most commonly caught and large numbers of discards of this
species at sea go unreported. Thresher sharks could also be very
sensitive to fishing pressure because of their low reproductive rate
and the small populations in the area. Hammerhead catches appear
to have declined, although historical by-catch data are not available
for any species of shark.
They conclude that
international organisations
such as the Tuna Commissions
should be involved in the
collection of fisheries statistics
on the by-catch of pelagic
shark populations. Studies of
gear selectivity and discards
are needed to properly
evaluate shark by-catch in
these fisheries. Management
of the Atlantic swordfish fishery
should be reoriented to a multi-
species approach, with the
effect of the pelagic shark by-
catch and its economic
implications included in the management model. However, the joint
efforts of all nations operating longline fleets in the eastern Atlantic
are required to provide a full assessment of the status of shark
populations in the area.
Blue shark Prionace glauca. © 1989 by Sid F. Cook. All rights reserved.
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Editorial note:
The possibility of imposing an additional duty on the international
tuna management bodies (i.e. IATTC, ICCAT, IPTP/IOTC, SEAFDEC
and SPC/FFA), namely to undertake the monitoring of high seas shark
catches, has been put forward by a number of readers of Shark News
recently.
As one correspondent points out: they might not do so willingly,
because of the extra work involved and because it appears to be
outside their mandates. However, on this second point there are two
reasons why it should be included in their remit.
First, sharks are a significant by-catch of most tuna fleets; with
present high fin prices they cannot be disregarded from economic
analyses.
Secondly, oceanic sharks and tunas often school together; a full
understanding of tuna ecology and population dynamics cannot be
achieved without an understanding of their associations with
sharks.
Readers' comments on this suggestion would be received with
interest.
Letter to the editor
Dear shark lovers,
It pleases me immensely to announce that the Portuguese Fisheries
Department is finally devoting some attention to sharks. The project
focuses on deep-sea fish and crustaceans and I have been invited to
deal with the shark component. At this point we are studying age and
growth of black-mouthed catsharks Caleus melastomus using the
sharks' vertebrae but, eventually, we'll move on to other deep sea
sharks and also stomach contents. The overall objective is to
understand the food chain processes that occur in deep waters.
Sincerely,
Joao Pedro Correia,
Curator of Sharks (Lisbon Zoo) and
Researcher (Portuguese Institute of Marine Research)
Editors' note:
This is the first letter to the editor received by Shark News, and it was
most gratefully received! Please remember that we are interested in
receiving more information from our readers, although we do not
guarantee to publish every communication sent to us.
Occurrence of Odontaspis ferox in the Western
Equatorial Atlantic
A dry jaw received from fishermen operating off Natal, north-eastern
Brazil, has been deposited in the Departamento de Pesca of the
Universidade Federal Rural de Pemambuco, Recife, Brazil. The
researchers who identified the species from its dentition (Roberto
Menni, Fabio Hazin and Rosangela Lessa) note that this represents a
notable large new extension to its known range.
[More details are available from the above-named at Depart.de
Pesca, Univ. Fed. Rural de Pemambuco, Brazil.]
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