Identifying Hotspots For Spatial Management Of The Indonesian Deep-Slope Demersal Fishery

The Indonesian deep-slope demersal fishery targets mostly snappers and groupers and is vital for the wellbeing of millions of people. More than 100 species are captured at depths of 50-500 m along shelves and seamounts using mostly droplines and bottom longlines. The main target species are Pristipomoides multidens, Pristipomoides filamentosus, Pristipomoides typus, Atrobucca brevis, Epinephelus areolatus, and Lutjanus malabaricus. The fleet in this fishery is predominantly unlicensed small-scale (1-10 gross ton) vessels. The fishery is unmanaged and lacks data that would allow policymakers to formulate sustainable management strategies. Here, we use fisheries-dependent data on catch composition, as well as fishing location and gear type, to determine factors that dictate catch composition and catches containing high proportions of immature fishes. Results indicate that immature fish assemblages are caught in particular locations, or "hotspots," through a combination of fishing gear and habitat characteristics. The important "hotspots" occurred in the Java Sea-Makassar Strait area. Only 2.4% of marine protected areas (MPAs) were located within "hotspots." Our findings highlight places of high conservation priority, such as the Java Sea, where expansion of current MPAs would greatly benefit the deep-slope demersal fishery in Indonesia by reducing immature catches, thus identifying a preexisting management that is appropriate for the sustainability of this fishery. The modeling methods we developed are transferable to other fisheries that lack data on fish abundance in order to prioritize management and conservation.