標識放流の実験的研究

概要

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(1) Tagging experiments were carried out in ponds with Mugii cephalus and Carassius auratus as the materials in order to test the twofold effects on the fish; the one was the wound directly inflicted by the tagging operation, and the other was the lengthy effect of the tag which lasted for a long time after the operation. (2) In Mugil, the former effect was scarce; the mortality cases of the tagged fish in 23 days after their liberation were almost as little as that of untagged ones. The latter effect was, however, remarkable; the growth rate and fatness (Body weight/Body lengthy3) of the tagged fish in about ten months after the operation was much less than those of the untagged ones, and owing to the said ill effect lots of tagged fish died from the cold weather. In Carassius, the either effect did not occur at all. (3) The method usually used for estimating the stock of fish by the total catch and the recapturing rate of marked fish was examined with Cyprinus carpio and Carassius auratus. The conclusion was as follows: in marking or tagging experiments we should be careful for the method of fishing, i.e. when the fish caught by angling were marked and liberated in the pond, the rate of reangling of the marked fish was much larger than that of angling of unmarked ones, therefore the total stock of the fish underestimated.
社団法人日本水産学会の論文