垂直網の網目と魚体の大きさとの関係

Abstract

As a fundamental experiment concerning effect of lift net, the authors studied the relation between mesh sizes and fish lengths of catches in model lift nets. The set of the observation was shown in Fig. 1. as a material of fish was used Carp Cyprinus carpio. Population of the carps in the tank is explained on the upper column of Table 1. as the total number 197 individuals. They were taken into consideration on the population to be approached in the natural condition. Net materials were used of mesh sizes 6, 3 and 1.5cm. and the lifting speeds of the net were selected 3 grades at 5, 10 and 20 seconds per 88cm. The results obtained were shown in Table 1. and Fig. 2. for the number of the fish lifted and the catching rate. Fig. 3. were shown a effect what is a indicator of catching efficiency against a certain mesh size and fish length.