A potential indicator for non-retained sharks in support of an ICCAT ecosystems report card

This work follows the requests and ongoing work from the ICCAT Sub-Committee on
Ecosystems to develop an Ecosystem report card, in this case related with non-retained
sharks. As a starting point, the bigeye thresher shark was used given its low productivity
and susceptibility to longline fisheries, determined in the latest sharks ERA. The
preliminary indicator developed now is based on a standardized CPUE from operational
level fishery observer data, from the Portuguese pelagic longline fleet (2008-2016). This
indicator should be considered preliminary, at this stage provided mostly as a starting
point for discussion at the SC-ECO, since it only has data from one fleet. If there is an
interest to progress the development of these types of indicator, then it is recommended
that detailed observer data from other fleets should be incorporated, especially fleets from
CPCs that interact more with those pelagic shark species.