About Mitigation Techniques

What is a bycatch mitigation technique?

A bycatch mitigation technique is a method that fishers or fishery managers can use to reduce catch of non-target species. It may involve a change in fishing practice, such as reducing longline soak time or avoiding protected species 'hot spots', or a change in gear, such as using circle hooks instead of J hooks. BMIS descriptions of mitigation techniques summarize their performance and refinement in experimental situations. Where RFMO conservation measures encourage or require the use of bycatch mitigation techniques listed in the BMIS, these can be found in the Regulations database.

Effective** - We use a 'tick' () to identify those mitigation techniques which have proven most effective at preventing the capture of non-target species or facilitate their alive post-capture release [1]. Follow these links to short descriptions of successful MT by species group: Sea Turtles, Seabirds, Sharks & Rays, Marine Mammals.

While mitigation techniques are listed individually in this database, it is important to recognise that a holistic approach to their implementation is necessary. While many mitigation techniques are effective across fisheries and provide mutual benefits, some result in trade-offs between different at-risk species groups (cross-taxa effects). Hook pods are designed to benefit seabirds; they are not expected to be problematic for other bycatch species. With further development, they may provide benefits to sea turtles if the barb of the hook can remain protected until deeper than is useful for seabirds, i.e., until it passes through the zone in which sea turtles spend the majority of their time. In another example, while using small fish species for bait instead of squid results in large reductions in sea turtle catch rates, for most species of sharks there is an opposite effect of bait type [2]. There is also a higher incidence of deep hooking sharks with fish bait instead of squid bait. Therefore, switching bait from squid to fish reduces impacts on turtles but increases impacts on sharks [2].

In compiling mitigation technique summaries, the BMIS will endeavour to address cross-taxa interactions. Additionally, for each bycatch species group, an overview of mitigation techniques that have been shown to be effective, as well as promising techniques and comments on cross­­­-taxa interactions are presented.

  1. Swimmer Y, Zollett E, Gutierrez A (2020) Bycatch mitigation of protected and threatened species in tuna purse seine and longline fisheries. Endang Species Res 43:517–542. https://doi.org/10.3354/esr01069
  2. Gilman E (2016) Mitigating Problematic Bycatch in Tuna Fisheries. In: ISSF News - Blog. http://iss-foundation.org/mitigating-problematic-bycatch-in-tuna-fisheries/. Accessed 17 May 2016