About Species Groups

In the BMIS, the term ‘bycatch’ mainly refers to the incidental capture of non-target species, including seabirds, sea turtles, sharks and rays, and marine mammals, in oceanic longline, purse-seine and gillnet tuna and billfish fisheries. Sharks are always treated as bycatch for the purposes of the BMIS, although they may be targeted or treated as an associated catch in some tuna fisheries. These four species groups are of special interest as they are characteristically highly migratory, with low reproductive rates (i.e., slow growth rates, late maturation, long gestation, low fecundity and long lives) [1]. As such, they may be may be more heavily impacted by high levels of incidental catch.

The nature of bycatch interactions for each species group and the mitigation techniques that are applied or are a focus of research are briefly discussed for each group. Safe handling and release techniques are applicable to all species groups and have been demonstrated to be an effective means of reducing bycatch mortality. Furthermore, there is increasing application of spatial and temporal measures to avoid bycatch interactions, whether incorporated in Conservation and Management measures and/or used as a dynamic fleet or vessel management tool.


  1. Poisson, F., Vernet, A.L., Seret, B., and Dagorn, L. 2012. Good practices to reduce the mortality of sharks and rays caught incidentally by the tropical tuna purse seiners. EU FP7, EBFMtuna-2012 Montpellier, France.