Using Fisheries Data to Inform Practical Approaches for Improving the Sustainability of a Targeted Shark Fishery – Lessons from Tanjung Luar

Overfishing is a major threat to sharks, driven by demand for high-value fins, as well as meat, liver oil, skin and cartilage. Several shark species have recently received increased international protection under the... [ view full abstract ]

Overfishing is a major threat to sharks, driven by demand for high-value fins, as well as meat, liver oil, skin and cartilage. Several shark species have recently received increased international protection under the Convention on the International Trade of Endangered Species (CITES), however, trade regulations alone will be insufficient to reduce overexploitation, practical fisheries management measures are essential for reducing fishing mortality.  Tanjung Luar is a major targeted shark and ray fishery in Indonesia. WCS conducted daily landing monitoring at Tanjung Luar from January 2014 to December 2016, with the aim of understanding the biological and operational characteristics of the fishery to inform management. We recorded 20,725 landed individuals across 82 species, a high proportion of which were threatened and protected.  We found that 62% are caught by drift longline, 35% are caught by set bottom long line and 3% are caught as bycatch in gillnets, with differences in species composition and catches size for the different gear types. The most significant factors influencing catch of threatened and protected species are month, fishing ground, engine size and hook number. We also observed significant negative relationships between catch per 100 hooks per haul and several indicators of fishing effort, suggesting diminishing returns above relatively low levels of effort.  Our results suggest that management measures focusing on fishing effort controls, gear restrictions and modifications and spatio-temporal closures could have significant benefits for the conservation of shark species, and may help to improve the overall sustainability of the Tanjung Luar shark fishery.