1999年2月黄海声学调查鳀鱼种群群体结构评估

IntroductionEstimation of the size structure of a fish population is often one of the primary objectives of an acoustic/trawl survey (Gunderson 1993;Honkalehto and Williamson 1996 ) .The size structure contains much informa-tion enabling a quick estimate of the fishable size of a stock in a regulated fishery or the recruitment status ofa stock.It is also a common practice to use the number at length of a population together with the age/lengthkey to produce the age structure of the fish popul…

The acoustic survey of anchovy in the Yellow Sea i n February 1999,with emphasis on the estimation of the size structure of the anchovy population

Estimation of the size structure of a fish population is often one of the primary objectives of an acoustic/trawl survey.The methods of estimation may be different with different sampling strategies.This paper describes the main results as well as the methods used during the acoustic survey of anchovy in the Yellow Sea in February 1999,with emphasis on the estimation of the number at length and biomass at length of the anchovy population surveyed under adoptive sampling strategy.The estimation is done for each transect.Within each transect,the biological sample data is weighted by fish quantity derived from the acoustic density ( s A) of the echo signs that the biological sample represents.This method makes full use of the acoustic data available in a rigorous manner.It is essentially to estimate the size structure of each group of fish aggregation thought to having similar size composition.It is believed that this method may lead to a more accurate estimate of the size structure of a fish population surveyed under adoptive sampling strategy.