Review of methods used to reduce risks of cetacean bycatch and entanglements

Fisheries bycatch is considered to be the greatest threat to cetaceans globally. From coastal artisanal fisheries to deep - sea industrial operations, incidental capture of whales, dolphins and porpoises in a range of fishing gear has resulted in serious welfare and conservation issues for many cetacean species, sometimes to the point of regional extinction. Whilst there has been concern about bycatch for several decades and attempts to find solutions, progress has been limited. Through the use of case studies, this report summarises the mitigation methods that have been undertaken with the objective of reducing cetacean bycatch, and assesses their efficacy and future potential. These include methods for reducing risk of contact between cetaceans and fishing gear, such as effort reduction, fishi ng bans and gear modifications, together with methods for reducing harm should entanglement occur. This review is intended to support initiatives to address cetacean bycatch, including those by CMS, its associated regional agreements, ASCOBANS and ACCOBAMS, and the IWC, by providing a summary of the current state of mitigation techniques. The review focusses on specific technical measures but these need to be considered as part of overall strategies involving all stakeholders. There are rather few examples of implemented mitigation measures substantially reducing cetacean bycatch. Enforcement and compliance are key to the success of any measures, and the lack thereof has been the cause of many mitigation programmes’ failure to meet their objectives. Generally, mitigating cetacean bycatch has not been viewed as intrinsic to successful fisheries management, but rather as a separate management issue. However, where reductions in bycatch have occurred, a feature of these situations has often been that a systemic change in the fishery itself has resulted in reduced cetacean bycatch, rather than the success of any mitigation measures specifically imposed for cetaceans. Given the pressing need for improvements in fisheries management globally, reduction of cetacean bycatch should be seen as a key part of such initiatives. The most generally effective mitigation of cetacean bycatch and entanglement is reduction in effort, starting with those fisheries that have the largest bycatch.