In Hawai‘i, the diet of endangered main Hawaiian Islands false killer whales (FKWs) includes pelagic and nearshore game fish, overlapping almost entirely with fishery catches. Interactions with nearshore fisheries are one of the greatest threats to this population, with at least 23% of individuals having injuries suggesting fishery interactions. Meetings with stakeholders have primarily brought fishermen to the table that fish off Kona, the area within the islands with the highest levels of fisheries effort/catch. At-sea observer or electronic monitoring programs to assess interactions and bycatch have been discussed, but there are more than 3,000 fishing license holders in Hawai‘i, and prioritizing monitoring locations is needed. To determine the areas of greatest overlap between FKWs and fisheries, we developed an index using satellite tag (n=28) and fisheries catch data (from 1994-2014). The index reflects the probability of a fishermen encountering FKWs relative to fish catch by area, which should reflect the likelihood of depredation and potential bycatch. Probabilities for each area were scaled relative to Kona (=1). Of the 97 fisheries statistical areas that overlapped with FKWs, nine areas had 52% of the catch, and FKWs spent just 7.4% of their time in those areas. Areas east of O‘ahu and north of Moloka‘i and Maui had overlap index values ranging from 124 to 782 times that of Kona, while areas off the north end of Hawai‘i Island had index values ranging from 65 to 2,887 times that of Kona. Our results suggest that management agencies need to bring fishermen who fish in these high overlap index areas to the table, in order to inform discussions of depredation, bycatch and potential solutions. Efforts to reduce and monitor fisheries interactions, including outreach efforts with fishermen, and possible observer or electronic monitoring programs, should concentrate on these areas with high index values.
Citation:
Baird, R., D. Anderson, D. Webster. 2017. Bringing the right fishermen to the table: An index of overlap between false killer whales and nearshore fisheries in Hawai‘i, with implications for targeting observer programs and outreach efforts. Abstract (Proceedings) 22nd Biennial on the Biology of Marine Mammals, Halifax, Nova Scotia, October 22-27, 2017.