Abstract: In order to evaluate the comprehensive impact of fishing on fishery ecosystem, and to establish a decision support system for the protection and management of this ecosystem, an impact evaluation model of fishing on fishery ecosystem was constructed, based on the PSR (pressure-state-response) model and by using analytic hierarchy process (AHP). The constructed model included 3 hierarchies and 9 indices (quantity of fishing vessels, fishing pressure index, fish catches, bottom fish rate, fish trophic level, single weight of dominant fish species, economic fish catches, diversity index, and evenness index), and applied to quantitatively evaluate the fishery ecosystem in Changshan archipelago area, based on the investigation data in 1987-1988 and 2006-2007. The results indicated that with the increasing fishing pressure in past twenty years, the ecosystem structure and function in study area shifted drastically, with the biomass of long-lived, high trophic level, and piscivorous fishes declined while short-lived and small fishes dominated gradually. According to the model and the degradation rate such as fish resources (4.75%), bottom fish rate (3.64%), fish trophic level (0.31%), single weight of dominant fish species (4.28%), economic fish catches 2.32%), diversity index (0.39%) and evenness index (1.14%), the fishery ecosystem health index (0.34) was below the evaluation grade III, showing that the fishery ecosystem in Changshan archipelago area was in unhealthy state in past twenty years.

Key words: Evolution, Specialization, Concept