Comparison on resources community of stow-net fishery before and after fishing off season in Huangmaohai Estuary

Abundance-biomass comparison curve and biomass spectra methods were applied to analyze the data collected from stow-net fishery before and after fishing off season (spring and summer) in Huangmaohai Estuary so as to evaluate the status of fishery resources community. Fivty-six fishery species were collected during the surveys, including 47 fish species (12 orders, 27 families, 38 genera) and 9 crustacean species (2 orders, 5 families and 7 genera). The catch species in spring were more than that in summer. In spring, the dominant species were Coilia mystus, Odontamblyopus rubicundus and Exopalaemon carinicauda. In summer, the dominant species were C.mystus, Anchoviella commersonii and O.rubicundus. The k-dominance curves of abundance and biomass intersected in spring, and the W-statistic value was -0.015. But the k-dominance curve of abundance was above the biomass curve in summer with the W-statistic value of -0.046. This phenomenon indicates that the present resources community of stow-net fishery was disturbed moderately in spring, but disturbed seriously in summer. Furthermore, the slopes of normalized biomass spectra in spring were higher than -1, and the biomass increased with the increase of the average individual weight, but preferred the opposite in summer. The results indicate that fishing can affect the biomass spectra, and the fishing off season does not play an obviously positive role by the decline of the slope of biomass spectra under overfishing. To maintain the ecosystem health, management and restrictions must be imposed on the fishery.