Abstract:

The investigation on the species composition and biodiversity of fish community in Hukou section of the Yangtze River was carried out two times monthly from 2007 to 2009,including  five times in AprilJune.A total of 26 species and 4 243 individuals were collected,belonging to 19 genera,7 families.The dominant species were 〖WTBX〗Pseudobagrus fulvidraco〖WTBZ〗 and 〖WTBX〗Leiocassi crassilabi〖WTBZ〗，accounting for 6403% of the total fish species.The eigenvalues of species diversity were Shannonwiener’s index (〖WTBX〗H〖WTBZ〗′) being 1782，Simpson’s (〖WTBX〗λ〖WTBZ〗 ) being 054，Pielou’s index (〖WTBX〗J〖WTBZ〗′) being 0547，Margalef’s index(〖WTBX〗D〖WTBZ〗) being 2993,Wilhm's index (〖WTBX〗H〖WTBZ〗″) being 1873 and Relative rare species (〖WTBX〗R〖WTBZ〗) being 5769%.In the fish community,middlesmall fishes with a mean body weight 50-500 g were the most superior in numbers,but big fishes with a mean body weight more than 500 g were the less percentage in numbers,the capture size of commercial fishes became smaller,and the stability and biodiversity of fish community were lower levels in the Hukou section.The fish community could be classified into 3 ecological types， i.e.，riversea estuarine fish (3 species )，riverlake estuarine fish (4 species )，migratory fish (19 species)；piscivorous fishs (8 species )，invertebrate fish (11 species)，omnivorous fishes (3 species)，planktivorous fish (2 species),herbivorous fish (2 species