陸奥湾におけるマガレイとマコガレイ成魚の生活年周期
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概要
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In order to elucidate the annual life period of adult L. herzensteini and L. yokohamae in Mutsu Bay, Aomori prefecture, the seasonal changes in several physiological conditions, i.e. the gonadsomatic index, hepatosomatic index, and condition factor of samples chiefly obtained with the trawl nets from April 1978 to November 1981 were examined. In addition, feeding intensity was investigated from stomach contents weight index and feeding frequency per day. As the results, the annual life period of L. yokohamae was divided roughly into the following four: spawning (fasting)-wintering (inactive feeding)-recovering (active feeding)-maturing (inactive feeding). On the other hand, that of L. herzensteini was divided into the three periods without the wintering. Although in winter they escaped the cold water (2-3℃) and were concentrated in the area near the entrance of bay, L. yokohamae hardly intook food and the feeding activity of L. herzensteini was also inactive probably on account of low temperature and inadequate food supply. In spring both species commenced active feeding having two feeding periods per day, and their food intake rates gradually declined after summer (one feeding peak) when hepatosomatic index and condition factor attained peak in the seasonal cycle, irrespective of temperature, food supply, and other external factors. It seems probable that such seasonal changes in feeding intensity are closely connected with the degree of food requirement in relation to their fat contents.
- 日本水産学会 = The Japanese Society of Scientific Fisheriesの論文
日本水産学会 = The Japanese Society of Scientific Fisheries | 論文
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