Post-release survival of juvenile silky sharks captured in a tropical tuna purse seine fishery
نویسندگان
چکیده
Juvenile silky sharks Carcharhinus falciformis comprise the largest component of the incidental elasmobranch catch taken in tropical tuna purse seine fisheries. During a chartered cruise on board a tuna purse seine vessel conducting typical fishing operations we investigated the post-release survival and rates of interaction with fishing gear of incidentally captured silky sharks using a combination of satellite linked pop-up tags and blood chemistry analysis. To identify trends in survival probability and the point in the fishing interaction when sharks sustain the injuries that lead to mortality, sharks were sampled during every stage of the fishing procedure. The total mortality rates of silky sharks captured in purse seine gear was found to exceed 84%. We found survival to precipitously decline once the silky sharks had been confined in the sack portion of the net just prior to loading. Additionally, shark interactions recorded by the scientists were markedly higher than those recorded by vessel officers and the fishery observer. Future efforts to reduce the impact of purse seine fishing on silky shark populations should be focused on avoidance or releasing sharks while they are still free swimming.
منابع مشابه
Trade-offs in the design of fishery closures: management of silky shark bycatch in the eastern Pacific Ocean tuna fishery.
Bycatch--the incidental catch of nontarget species--is a principal concern in marine conservation and fisheries management. In the eastern Pacific Ocean tuna fishery, a large fraction of nonmammal bycatch is captured by purse-seine gear when nets are deployed around floating objects. We examined the spatial distribution of a dominant species in this fishery's bycatch, the apex predator silky sh...
متن کاملBycatch in the Maldivian pole-and-line tuna fishery
Tropical tuna fisheries are among the largest worldwide, with some having significant bycatch issues. However, pole-and-line tuna fisheries are widely believed to have low bycatch rates, although these have rarely been quantified. The Maldives has an important pole-and-line fishery, targeting skipjack tuna (Katsuwonus pelamis). In the Maldives, 106 pole-and-line tuna fishing days were observed ...
متن کاملShort communication: Identification of By-catch species of tuna purse seiners in Iranian waters of Oman Sea
Tuna purse seine fishery is a commercial and industrial fishery in the Iranian waters of Oman Sea. An observer programme was conducted to identify the by-catch composition of the tuna purse seine fishery in the Iranian waters of the Oman Sea. Investigations were carried out on board of purse seiner vessel “named Parsian Shila” between September and October 2015. The by-catch was composed of 17 ...
متن کاملAn Indicator-based Analysis of Key Shark Species based on Data Held by SPC-OFP
Longline and purse seine logsheet and observer datasets held by SPC-OFP were examined to assess the stock status of eight WCPFC key shark species. Both longline and purse seine logsheet datasets suffer from missing shark catch records and a lack of species-specific recording, therefore the indicator analysis was based on observer data only. Shark data from the observer data sets are, however, a...
متن کاملPresent and Future Potential Habitat Distribution of Carcharhinus falciformis and Canthidermis maculata By-Catch Species in the Tropical Tuna Purse-Seine Fishery under Climate Change
Citation: Lezama-Ochoa N, Murua H, Chust G, Van Loon E, Ruiz J, Hall M, Chavance P, Delgado De Molina A and Villarino E (2016) Present and Future Potential Habitat Distribution of Carcharhinus falciformis and Canthidermis maculata By-Catch Species in the Tropical Tuna Purse-Seine Fishery under Climate Change. Front. Mar. Sci. 3:34. doi: 10.3389/fmars.2016.00034 Present and Future Potential Habi...
متن کامل