空釣出現の検討-II
釣鈎の装着方法と餌サンマの切断力について
1973 年 39 巻 6 号 p. 605-609
詳細
1973 年 39 巻 6 号 p. 605-609
In the previous paper the breaking strength of a saury torn off from the hook of the tuna long line was studied.
It was shown in the first investigation that the breaking positions of the bait were at two points. One of them was the forehead, which was broken lengthwise, and the other was the neck. And the breaking strength of the former was smaller than that of the latter. In the case of tuna fishing, keeping the bait from falling off the hook is an essential condition to a good catch. Moreover, it is necessary for that purpose to increase the breaking strength of the bait. In the second investigation the breaking strength was measured by using different sticking methods. The methods adopted were as follows:
1. “Shallow” Sticking (i.e. stuck at the center of the head)
2. “Deep” Sticking (i.e. stuck at the back part of the cranium)
3. “Horizontal” Sticking
The breaking strength of the bait with increased soaking time was measured by the above three methods. The largest breaking strength was obtained by “Deep” Sticking. That a bait is hard to fall off the hook is one thing, and it is quite another that the mouth of a fish can be hooked easily. The interrelation between the two is an important problem for us to solve.
