日周的採取資料によるシロギスの産卵様式の推定

概要

論文の詳細を見る
記事区分：原著The purpose of this study was to describe the results of estimation of the spawning form of the Japanese whiting by means of daily collected samples. Results were compared with the knowledges obtained by other methods concerning with the spawning form. The results obtained from angled fish were summarized as follows. The sex ratio was somewhat biased to female through the time intervals to 13:00, and then becoming slightly biased to male after the time. GSI varied in the range from 1.0 to 7.0 , corresponding to the respective mean value of GSI and body length in fish angled within each time interval. Ovarian eggs were in 3 to 4 continuous size groups, of which the largest eggs group, larger than 0.50 mm after the time of 11:00, developed to be separated from the second largest eggs group with the lapse of time. From the egg size distribution, most of individuals seemed to be daily spawners. The number of largest eggs, being fitted to batch fecundity, was estimated in a large variation from 600 to 51,000. The total number of ovarian eggs was also estimated from 316,000 to 1,290,000, including countable small eggs more than 0.05 mm in diameter. The results obtained from present investigation were effective and seemed to be comparable with those of other various methods.