A recent article, published in the journal Marine Policy aims to suggest better methods for the handling of the bycatch of sharks and rays in purse-seine fisheries. Bycatch - when other marine animals are unintentionally caught alongside the target species - is a common problem of any non-discriminatory fishing method such as trawling and seine fishing. The most famous example of bycatch is the unintentional landing of dolphins by the tuna industry - as dolphins commonly aggregate with schools of yellowfin tuna they are enclosed in the nets along with the target species and can drown from being enclosed in these nets. However, whilst charismatic dolphins caused a great deal of public outcry regarding this fishing practice, other marine creatures such as turtles and sharks are also commonly caught as bycatch of the tuna fishing industry.
The team spent time on board French purse-seine tuna vessels in the Atlantic and Indian Oceans, observing the practices of the crews and also conducted interviews with purse-seine vessels at port to guage the attitude of crew members towards sharks and ray bycatch.
Presently sharks and rays which are caught as bycatch are released back into the sea by the French tropical tuna purse seine fishery. Bycatch may be released using manual handling techniques; naturally, this may result in danger to the crew from bites and stings (rays) as well as blows to the body from larger species such as whale sharks. Manual handling of sharks and rays (elasmobranchs) may also cause harm to the species - elasmobranchs have fragile, cartilaginous skeletons which are prone to dislocation and damage if handled incorrectly. In addition to this they may suffer organ damage when landed owing to the weight of their own bodies which are usually supported by the aquatic environment.
Whilst there is no economic incentive for fisheries personnel to ensure the live release of sharks and rays caught in their nets, the authors suggested that if practices to improve the live release rate of shark and rays species were quick and easy, then crews would be likely to improve their handling methods.
Successful removal of sharks and rays from the catch requires that the bycatch is anticipated and the crew are trained to handle these large animals correctly. The authors insist that good practice for handling sharks and rays should be taught and used by all members of the fishing industry - one of the worlds most dangerous industries. The manual produced by the authors has been distributed to skippers and posters showing good handling practice of elasmobranch bycatch are displayed on vessels. In addition to this, training workshops have helped to improve the knowledge of crews on the bycatch issues.
Whilst most environmentalists would prefer to see the purse-seine industry become illegal practice - owing to the large numbers of fish taken in one go and the bycatch problem - producing good practice measures for handling bycatch and trying to ensure the live release of sharks and rays accidentally caught in purse-seine nets is at least a step in the right direction for the fishing industry.
The original article can be accessed here or here.
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