Seasonal variation of fishery resources in Egong Bay, Shenzhen

ObjectiveThis research clarified the seasonal variation of fishery resources and its reasons in Egong Bay in Shenzhen, to provide reference for the sustainable utilization and management of fishery resources in typical fisheries area of South China Sea coasts. MethodBased on the data of fishery resources collected through trawl surveys in Egong Bay fisheries area, Shenzhen, from August(autumn) and December(winter) of 2012 to March(spring) and May(summer) of 2013, seasonal variation of nekton species composition, stock density, dominant species, size spectra and biodiversity were studied. ResultResults showed that there were 113 species of nekton, belonged to 18 genus, 50 families, 14 orders and 3 classes in this area. The species number was the largest in summer(61 species) and was the minimum in autumn(53 species). In spring and winter, there was 56 species. The stock density and tail stock density of nekton were the minimum in summer(5950.20 kg/km2 and 356.45 individual/km2 respectively), and the percentage of fish were the highest in this season(51.99% and 42.19%, respectively). Seasonal variation of size spectra indicated that fishing intensity was the highest in autumn, and was the lowest in summer. Additionally, the seasonal variation of biodiversity index was obvious, and the variation trend of Margalef richness index(D '), Shannon-Wiener diversity index(H ') and Pielou evenness index(J ') was the same, which was summer>spring>autumn>winter. ConclusionTherefore, there was clear seasonal variation in the nekton species, biomass and structure in Egong Bay fisheries area in Shenzhen. Community structure and function in su-mmer were more stable than that in autumn and winter, due to the difference of fishing intensity in different seasons(low intensity in summer and high intensity in autumn). Particularly, k selection species is replaced by r selection species with the increase of fishing intensity in autumn.