Fish species diversity in Zhongjieshan Islands Marine Protected Area (MPA)

The Zhongjieshan Islands Marine Protected Area (MPA) is located in the central area of the Zhoushan fishing ground. It lies to the east of Zhoushan Islands District in Zhejiang Province and is historically known as the "fish warehouse" of the East China Sea. Fish community taxonomy and eco-group data from eight bottom trawl surveys in Zhongjieshan Islands MPA, carried out from 2010 to 2012, were used to examine species composition in detail. Indices such as Margalef's species richness index, Shannon-Wiener's species diversity index, Pielou's species evenness index, resource density index as well as Pinkas's IRI were used to analyze the status of fish diversity in the protected area. A total of 55 fish species belonging to 2 classes, 12 orders, 32 families and 44 genera were collected during the survey. 26 species from the order Perciformes (accounting 47.3% of the total species) and 41 reef species (74.5% of the total species) were captured. There were 30 warm temperate species, 24 warm water species and 1 cold temperate species, and nearly 70% of total rare species were warm temperate species. There were 27 local species, 24 offshore migrating species and 24 seasonal species. Forty percent of the fish caught were demersal, 36.4% were meso-demersal and 23.6% were pelagic. The dominant species in each habitat layer was examined, Chaeturichthys stigmatias was the most abundant demersal fish, Harpodon nehereus was the most dominant meso-demersal fish. Fish in the family Engraulidae dominated the surface waters. The mean biomass index of the study area was highest in summer (1043.7 kg/km super(2)) and lowest in spring. The abundance density index was highest in spring (122x10 super(3) ind/km super(2)), but lowest in winter. Both the biomass index and the abundance density index in the highest season were significantly different from that in the lowest season (P