Outdoor tank experiments on the influence of soaking time on the catch efficiency of gillnets and entangling nets

Abstract

An outdoor tank experiment was conducted to study the influence of soaking time on the catch efficiency of gillnets and entangling nets (trammel and semi-trammel nets). The catch efficiency of the nets was also compared with detecting the difference between entangling nets and gillnets in relation to soaking time. Nets of the same mesh sizes were set simultaneously in separate outdoor tanks containing 200 rainbow trout ( Oncorhynchus mykiss) whose composition size was known. The experiment was carried out at night using four soaking times; 0.5, 1, 3 and 5 h. The variations of the catch efficiency of all nets had a U-shaped trend, showing that the efficiency increased at the shortest time (0.5 h), decreased at the intermediate time (1 h), and increased again at the longest soaking time. The average catch efficiency of the semi-trammel net appeared to be slightly higher than that of the gillnet.