Population Dynamic Characteristics And Sustainable Utilization Of The Anchovy Stock In The Yellow Sea

Recognizing that fisheries and ecosystems in general are in global decline, a profound paradigm shift in the management of marine fishery is underway. Ecosystem approach to fisheries based on ecosystem dynamics studies has become an inevitable development trend in fisheries management.Anchovy (Engraulis japonicus) is a key species in the Yellow Sea ecosystem. Since mid 1980s and before the initiation of a large-scale directed fishery in early 1990s, the anchovy stock in the Yellow Sea was fluctuating around 3 million tons; following the explosive development of the fishery, the anchovy stock underwent a rapid decline in late 1990s. In the beginning of 2003, the wintering stock dropped to a historic low of just above 100 thousand tons, and was on the brink of a total collapse.Under the umbrella of China-GLOBEC studies, and based on methodological developments on stock structure and resources estimation in the integrated acoustic and trawl surveys, population dynamic characteristics, including stock structure, stock-recruitment relationship and sustainable production of the anchovy stock were analyzed and estimated with data obtained since 1985; based on the findings from the these analysis, a tentative discussion on the sustainable utilization of the anchovy stock was also made. The objectives of this work were to provide concrete data for the study of the responsive mechanism of the anchovy stock to anthropogenic pressure and natural variations, and to provide basic materials for the ecosystem approach to the management of the anchovy stock to base. The main results are as follows.1. A method for the reconstruction of the size structure and the age structure of the anchovy stock using acoustic and adaptive trawl sample data was established, and the stock structure of the wintering anchovy since 1999 were estimated according to this method. Via the analysis of the structure of the spawning stock as well as that of the wintering stock, a degradation trend towards smaller size and lower age of the...