Nekton resources in northeast Beibu Gulf

The nekton in the northeast waters of Beibu Gulf had beeninvestigated during 2009~2010.There are 300 species of nektons in the waters, among which 209are fish (205 species of osteichthyes, 4 species of chondrichthyes), belonging to 15 orders, 70 families and 119 genera. Seventy-six crustanceans and 15 cephalopods are identified in the area.One hundredspecies of benthic fishes, 72 species of epibenthic fishes, 29 species of pelagic fishes and 8 species rockfishoccupy 47.85%, 34.45%, 13.87% and 3.83% of the total species of fishes, respectively.; and153 species of warm-water fish, 55 species of warm-temperature fish and 1 species of cold-temperature fish occupy 73.20%, 26.32% and 0.48% of the total species of fishes, respectively. The seasonal variation in the number of nekton species: summer＞autumn＞spring＞winter; density index of resources: summer＞autumn＞spring＞winter; density of fishery resources: summer＞autumn＞spring＞winter. The average density of fishery resources per year is 522.925 kgkm-2, equivalent to 10% of the primordial resources density. The biodiversity indexishighest in summer and autumn. The potential fishery resources and maximum allowable catch are estimated as 1.092105 and 5.460104 t per year in the northeast waters of Beibu Gulf. Besides, we discuss the changes of fishery resources in Beibu Gulf in history and provide advices for further conservation and management of fishery resources.