Tempo-spatial distribution of Evynnis cardinalis in Beibu Gulf

Evynnis cardinalis is one of the main commercial fish in Beibu Gulf, but its stocks fluctuated greatly resulting from long-term overfishing, which has significant effects on fishery production and population structure. Based on the offshore fishery resources survey during 2014~2015, the paper conducted a comprehensive analysis on seasonal variation and spatial distribution of E.cardinalis in Beibu Gulf by studying the catch per unit effort (CPUE) for biomass and number. The results suggest that E.cardinalis is widespread around Beibu Gulf with occurrence of over 86% for four seasons at present. Both CPUE for biomass and number showed obvious seasonal variation.The highest values in summer were 7.30 kg · h^-1 and 240.83 ind · h^-1 averagely, respectively, but the lowest values in winter were 1.76 kg · h^-1 and 21.94 ind · h^-1 averagely, respectively. For spatial distribution, high CPUE for biomass and number mainly occurred in northern sea area of 20°N in Beibu Gulf, but low value occurred in western sea area of Hainan Island. Moreover, it is found that implementation of resource conservation has made achievements across Beibu Gulf in recent years. Compared with the situation in 1990s, the stock of E.cardinalis has recovered. However, the analysis of biological characteristics for E.cardinalis indicates that population whose body length over 200 mm or weight greater than 80 g only occupied a small proportion. Thus, low-age and miniaturization are still serious problems for E.cardinalis. Some measures, such as increasing the smallest size of mesh and catch body length, should be taken to reduce the fishing intensity and make improvement in population structure.