Catching efficiency and selectivity of entangling nets

Fishing experiments for entangling nets (semi-trammel and trammel nets) of different mesh sizes and vertical slacks were conducted simultaneously in Tokyo Bay from 1986 to 1989. The purpose of the experiment was to compare the catch and to study the effect on the catching efficiency and selectivity of variations in the construction of the nets. From the overall catch, it was found out that the semi-trammel net was more efficient than the trammel net. However, based on the type of fish caught, the efficiency of the net is species selective. For gizzard shad ( Konosirus punctatus), which is the most abundant species caught, the following observations were made; (1) the semi-trammel net caught more fish than the trammel net for any vertical slack; (2) the selection range of 3.6 cm mesh size for both nets was wider compared to larger mesh sizes owing to several large individuals caught by entangling; (3) the master selectivity curve showed a similar pattern for both nets (skewed to the right) with the same modal value. However, the points on the right tail of the trammel net were more scattered.