Pelagic Fisheries

In general, the small neritic tuna species dominate the catches along the western coastline of Sarawak, Sabah and Brunei.  Coastal tuna landings are mainly represented by five species: Euthynnus affinis, Sarda orientalis, Thunnus tonggol, Thunnus alalunga and Katsuwonus pelamis (Buising, 1996). Oceanic species such as skipjack are found more frequently along the eastern coast where the continental shelf is narrow and consequently deep sea conditions and larger pelagic fish are found closer to shore. 

The larger species -- bigeye (Thunnus obesus) and yellow fin (T. albacares) -- are concentrated over the edge of the continental shelf, especially in the South China Sea, where it is suspected that there is localised and/or temporary upwelling which raises the productivity (Gambang, 1999).  The continental slope in the Southern South China Sea is steep, falling from 200 to 1000m in 5km and there are divergence and convergence currents, which vary with the monsoon season.