Elasmobranchs in southern Indonesian fisheries: the fisheries, the status of the stocks and management options

Abstract

The biology of elasmobranchs makes them very vulnerable to fishing pressure and there is increasing international concern over their exploitation. In northern Australia the stocks of some species may be shared with those in southern Indonesia. Indonesia has the highest landings of elasmobranchs worldwide ([100,000 t p.a.) and millions of Indonesian artisanal fishers rely heavily on elasmobranchs taken in target fisheries. They are also taken by industrial trawlers and as bycatch in pelagic tuna fisheries. This paper, resulting from a collaborative project between Australia and Indonesia, summarises the elasmobranch fisheries; the characteristics of the fisheries are outlined, the status of the stocks are assessed, and management options described and discussed. The project focussed on representative markets and fish landing sites in southern Indonesia from 2001 to 2005. Data were from market surveys, the records of the Indonesian Directorate General of Capture Fisheries, and from research cruises. Data from the ongoing tuna monitoring programme showed that shark bycatch from the tuna fleets forms about 11% of shark landings in Indonesia. Yield per recruit and related analyses were used to integrate biological information to indicate the productivity of each species to allow for management policy options and constraints. Research cruise data show that catch rates of elasmobranchs in the Java Sea declined by at least one order of magnitude between 1976 and 1997. The results indicate strongly that many of the shark and ray species in Indonesia are overfished and that the most effective management strategy may need to involve capacity control, such as licencing, gear restrictions and catch limits, together with controls on the fin trade.

Population genetic structure of blue-spotted maskray Neotrygon kuhlii and two other Indo-West Pacific stingray species (Myliobatiformes: Dasyatidae), inferred from size-polymorphic intron markers

“…The low fecundity and slow maturation of sharks and rays (elasmobranchs), in particular, make them highly vulnerable to overfishing. There is increasing concern over their exploitation in Indonesia, the most populated country of the central Indo-West Pacific (Blaber et al, 2009;White and Kyne, 2010). However, little effort for management and conservation has been made thus far (Blaber et al, 2009;White and Kyne, 2010).…”

“…There is increasing concern over their exploitation in Indonesia, the most populated country of the central Indo-West Pacific (Blaber et al, 2009;White and Kyne, 2010). However, little effort for management and conservation has been made thus far (Blaber et al, 2009;White and Kyne, 2010). If unsustainable exploitation is allowed to continue unmonitored and unregulated, it will cause the depletion of stocks, erode genetic diversity, and eventually lead to the extinction of many shark and ray species in this region.…”

Reconstructing the History and the Effects of Mechanization in a Small-Scale Fishery of Flores, Eastern Indonesia (1917–2014)

“…Fishermen have observed sharp reductions of fish populations, with benthic, elasmobranch, and coral species suffering a dramatic decline (Fox, 2005;Blaber et al, 2009;Tull, 2009;Christensen and Tull, 2014). The action of foreign vessels has been reported since the early 2000s, which may further compromise the integrity of marine stocks.…”

Catch and Relative Abundance of Some Sharks Landing in Tanjung in Luar, Lombok

“…Perikanan hiu di Indonesia telah berlangsung cukup lama sejalan dengan perkembangan perikanan tuna sebagai hasil tangkapan sampingan yang kemudian menjadi target tangkapan utama di beberapa tempat (Widodo dan Widodo 2002;Blaber et al 2009;Zainudin 2011). Salah satunya adalah di Tanjung Luar, Lombok Timur yang merupakan salah satu basis perikanan hiu terbesar di provinsi Nusa Tenggara Barat.…”