Niche and interspecific associations of dominant fishes in southern coastal waters in Taizhou, China

Based on the data from fishery resources survey carried out in southern coastal waters in Taizhou in October 2016 (autumn) and April 2017 (spring), this study defined the dominant species and main species that appeared in the two surveys as the dominant fish, and analyzed the niche and interspecific associations of dominant fish by the methods of index of relative importance, niche breadth, niche overlap, the variance ratio, Chi-square test, Pearson correlation test and Spearman rank correlation test. The results showed that there were 8 and 11 dominant fish species in autumn and spring respectively, and 5 common dominant fish species were in these two seasons. The index of niche breadth and overlap of dominant fish in autumn were slightly higher than those in spring. There were 4 wild niche species, 3 middle niche species and 1 narrow niche species in autumn, while 4 wild niche species, 5 middle niche species and 2 narrow niche species were in spring. The number of pairs with significant niche overlap in autumn accounted for 32.14% of the total pairs, while only 12.73% in spring. In autumn, overall interspecific associations indicated that significantly negative association existed among dominant fish species. Chi-square test, Pearson correlation test and Spearman rank correlation test showed that the positive and negative correlation ratios in the community were 1.50, 1.33 and 2.11 respectively, and the test significant rates were about 0%, 17.86% and 10.71% respectively. In spring, overall interspecific associations indicated that insignificantly negative association existed among dominant fish species. Chi-square test, Pearson correlation test and Spearman rank correlation test showed that the positive and negative correlation ratios in the community were 0.93, 0.90 and 1 respectively, and the test significance rates were about 9.1%, 18.18% and 21.82% respectively.