抄録
The optimum length and setting direction of the leader of a setnet were discussed.
Let l denote the length of leader of a setnet and a the depth of water at the end of the leader, then the values c in c=l/a were oalculated for different kinds of setnet seperately.
Distributions of the gradient g on fishing grounds were also determined by the formula g= (a-b)/l, where b is the depth of water at the starting point of the leader, and the relationship between g and c was ascertained.
In the case of the yellowtail trap net, the value of setting direction i which is expressed by the inclination of the leader was 0.23 or θ=13° on an average.
