Chondrichthyan guide for fisheries managers: A practical guide to mitigating chondrichthyan bycatch

Patterson HM, Tudman MJ (2009) Chondrichthyan guide for fisheries managers: A practical guide to mitigating chondrichthyan bycatch. Bureau of Rural Sciences and Australian Fisheries Management Authority, Canberra

Shark bycatch Chondrichthyans (sharks, skates and rays) typically display K-selected life history strategies whereby they are slow growing, late maturing and have low fecundities (Stevens et al. 2000). They are particularly vulnerable to exploitation and are slow to recover. Bycatch in marine fisheries is a source of mortality for chondrichthyan species as they are caught incidentally while targeting other species and may not survive when returned to the sea. Survivorship of live animals returned to the sea after being captured is often unknown.

Working group The Australian Fisheries Management Authority (AFMA) has been conducting ecological risk assessments (ERAs) for the fisheries under its jurisdiction. These assessments take numerous biological factors into account and give an indication of which species are at high risk from fishing in each fishery. In order to address and mitigate the risks to chondrichthyans identified as 'high risk' in this process, AFMA convened the Chondrichthyan Technical Working Group (CTWG). This working group consisted of recognised shark experts, as well as representatives from non-government organisations (NGOs), government departments and the fishing industry. The objectives of the CTWG were to provide practical mitigation options for the noted high risk chondrichthyan species and groups that could be implemented by AFMA in both the long and short-term and provide suggestions for directed research, including research which may remove species from the 'high risk' list. The information presented in this guide is based on the suggestions and opinions of the CTWG.

Mitigation options The CTWG discussed several shark groups and subgroups including dogfish, pelagic sharks, skates, rays and hammerheads/whalers. The group also briefly discussed Threatened, Endangered and Protected (TEP) species of sharks. Each group or subgroup was discussed and mitigation options put forward. These options were then ranked and assessed qualitatively against a series of criteria. These rankings are presented in tables and are followed by detailed comments of the CTWG. The CTWG also provided general recommendations about the options that could be implemented immediately versus those that required more research. Finally, the group noted which options would likely work well together and more specific comments on the options that are most viable.

Conclusions The CTWG concluded that there is no panacea for the problem of chondrichthyan bycatch in marine fisheries, but that this guide will provide managers with the most appropriate options to mitigate fisheries impacts and improve the survival of chondrichthyan species. Indeed, it was noted that addressing chondrichthyan bycatch is a problem for fisheries management agencies world wide. It was also noted that what works for one fishery may not be suitable for another, and that managers will have to weigh their options and work with industry and other stakeholders to determine which is best for their fishery. This guide will aid in such decisions. In many cases practical changes in the way fishing is conducted are required to improve the survivorship of these important animals.