Comparative analysis on catch composition with two fishing gears at Yellow River estuary in spring

Based on the survey data obtained by beam trawl and single-boat bottom trawl at Yellow River estuary in May 2007, a comparative study on the catch composition with two fishing gears was analyzed; indices of Sorensen similarity (Ss), species richness (R), Shannon-Wiener diversity (H), Pielou evenness(J) and index of relative importance (IRI) were calculated. The similarity of catch composition between beam trawl and bottom trawl was relatively small with a Sorensen similarity of 0.63. Indices R，H' and J' of beam trawl were 3.61, 2.28, 0.64 and those of bottom trawl were 3.55, 2.40, 0.72, respectively. The results showed that the diversity of bottom trawl was greater than that of beam trawl. It is suggested that the catch per unit effort of the two fishing gears was low with a poor selectivity, which would be greatly harmful to young individuals.