Preliminary report on an artisanal fishery for thresher sharks (Alopias spp) in Tawi-Tawi, Southern Philippines

Abstract

Thresher sharks (family Alopiidae) are highly migratory pelagic predators whose populations have drastically declined due to extensive fishing for their fins. There are only three species of thresher sharks worldwide. The International Union for Conservation of Nature (IUCN) has listed pelagic (A. pelagicus) thresher sharks as endangered while bigeye (Alopias superciliosus) and common (A. vulpinus) thresher sharks as vulnerable to extinction. There is limited scientific information about thresher shark fisheries in the Philipines. In this study we described a thresher shark fishery in Tawi-Tawi, Southern Philippines which has been existing for more than 20 years now. The fishery is generally small-scale, using simple hook and line and 13-hp inboard motorized boats with a capacity of one to two fishers per boat. Fishing is year-round with peak season occurring from March to May. Fishers spend about 10 days per month fishing during neap tide when the currents are weak. All three species of thresher sharks are caught in Tawi-Tawi. They are generally hunted for their fins and meat which are sold to local buyers. About 50 boats fish per day with about half of them catching one to two sharks. Our study suggests that monthly production of thresher sharks during the peak season in 2018 was about 15.3 mt or valued at about US$19,886.39. Our study is the first to report that the Sibutu Passage is an important fishing grounds for thresher sharks which must be put under immediate protection for effective conservation of these valuable species.