トビゴイに関する研究(第2報) : 餌料の粒子組成と量の影響

概要

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As a part of a series of experiments to determine how and why the shoot carp occur, carp fry a few days after hatching were reared with food of different particle size and of different quantity. Their body length distribution was analyzed with the following results: (1) Body length distribution is approximately symmetrical in the batch of fry fed with small-particle food (cladocerans passing through the 400 μ mesh), but skewed conspicuously in the batch fed with larger particles (cladocerans and mosquito larvae), indicating the occurrence of the shoot carp. (2) When comparative batches of fry are given the same food in different quantity, the shoot carp occur, i.e. the length distribution is skewed with the mode in smaller length, more conspicuously in the batch fed with “defi ?? ent” quantity of food than in those given “moderate” or “plentiful” quantity. These results seem to indicate that competition for food between the individual fry within a batch is an important causative factor of the occurrence of the shoot carp.
公益社団法人日本水産学会の論文