The IUCN/SSC Shark Specialist Group
Shark News 14: March 2002
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Bycatch and Lost Catch in the Uruguayan Longline Fishery
Andrés Domingo, Dirección Nacional de Recursos Acuáticos, Uruguay
Swordfish are the main target of the Uruguayan longline fleet which
began its activity in 1969. Currently there are nine operating vessels
(Mora and Domingo 2001). In 1998, DINARA (the government office
in charge of marine and aquatic resources) began conducting an
observer program onboard the fleet, with the purpose of obtaining
information on the target species (swordfish, bigeye tuna, yellowfin
tuna), and those caught as incidental catch (albacore, sharks).
Though shark fins were not traditionally a target of the fishery, there
is an increasing fishing effort for this product, and it has become one
of the main targets in many of the fishing trips. Traditionally, fins
belonged to the crew. However, as a result of the population growth
the increase in purchasing power of Eastern markets and the popularity
of shark fin soup, there is a growing demand for shark fins which often
reaches the highest prices among sea products. For this reason fins are
now shared, in most cases fifty-fifty between the crew and the company.
Another consequence of the increasing demand is that juvenile
specimens previously released are now discarded after finning.
Ten trips with scientific observers were made between 1998 and
2000, and 153 longline sets were monitored. It was found that all
sharks caught were finned. Shark bycatch fluctuated between 7-37%
of the total capture, and between 18-70% of the captured
elasmobranchs. Most of the bycatch consisted of blue sharks less than
1.50 m in length, together with several other species of carcharhinids.
There is a proportion of the total capture that becomes detached
from the gear at the moment of recovery. This is known as lost catch
and can be caused by operating problems (for example, the tension of
the gear, if contrary to the direction of the ship may cause the fish to be
lost if the ship does not stop in time), or due to the conflicting interests
of the skipper and crew (the skipper is paid only for the target species,
whereas the crew earnings are based on the total catch, thus if the
species caught are not valuable for the skipper, he will not stop the
vessel) (Domingo et al. 2001). The lost catch was found to amount to
4-7% of the total capture, with over 50% of the lost catch consisting of
elasmobranchs.
Considering that the operating modality of the Uruguayan fleet is
similar to that of others operating in the South Western Atlantic Ocean,
we believe that the performance of these other fleets are likely to be
similar to those described here. The pressure of these fleets in search
of fins from juvenile sharks together with the lost catch values indicate
that the mortality values due to fishing may differ significantly from
values obtained from landing declarations and logbooks. The best way
of determining the impact of these fisheries on resources is through
scientific observation programs.
References
Mora O. and A. Domingo. 2001. Informe Nacional de Uruguay,
ICCAT, COM/01, Murcia, España.
Domingo A., O. Mora and M. Cornes. 2001. Evolución de las capturas
de Elasmobranquios pelágicos en la pesquería de atunes de
Uruguay, con énfasis en los tiburones azul (Prionace glauca), moro
(Isurus oxyrinchus) y porbeagle (Lamna nasus). ICCAT, SCRS/01/
74. España.
Andrés Domingo
Dirección Nacional de Recursos Acuáticos
Recursos Pelágicos, Montevideo- Uruguay
Fax: (5982) 4013216
Email: adomingo@adinet.com.uy or
adomingo@dinara.gub.uy
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