Pelagic shark fisheries of Indonesia's Eastern Indian Ocean Fisheries Management Region

Abstract

Sharks are commonly caught in Indonesian waters both by target fisheries and as bycatch. Fishers targeting sharks mostly employ drift longlines, whereas tuna longlines and gillnets are the gear mostly responsible for shark bycatch. Our studies on shark fisheries have been conducted since 2006 and have focused on the eastern Indian Ocean region, the most exploited area in Indonesian waters. Sharks are mostly landed as bycatch in the tuna fishery (using longlines and gillnets) in Cilacap, Central Java province, and as targeted catch by the pelagic shark fishery at Tanjung Luar (Lombok, West Nusa Tenggara province), one of the largest targeted shark fisheries in Indonesia. Eight years (2006–2013) of monthly shark bycatch data from the fishing port at Cilacap and one year (February 2012–January 2013) of daily catch data from Tanjung Luar were analysed to determine their respective contributions to shark landings in Indonesia's Eastern Indian Ocean Fisheries Management Region. A total catch of 1 364 t of sharks was recorded at Cilacap, with an average monthly catch of 14.2 t (SD 18.5). A total of 1 426 sharks were recorded at Tanjung Luar, with an average daily catch of five individuals. Whaler sharks (Carcharhinidae) were the most commonly caught in both fisheries, consisting primarily of silky sharks Carcharhinus falciformis in the targeted fishery and blue sharks Prionace glauca in the tuna fishery. Overall, the Cilacap bycatch contributed 4.7% of the annual shark landings in the region. In 2012, the fishery at Tanjung Luar contributed 5.2% of the regional shark landings. The relatively low recorded contributions of these two fisheries may be inaccurate and may reflect double‑counting at the provincial level. Given the different shark species composition, the two fisheries require different management and conservation strategies to be included in Indonesia's National Plan of Action for the Conservation and Management of Sharks (NPOA‑Sharks).