The research group of Associate Professor Seiji Akiyama of Tokyokaiyo University, in collaboration with the Fisheries Research and Education Agency, Aomori Prefectural Industrial Technology Center, etc., has developed a new technology to select small bluefin tuna fish caught in a set net and release them alive. bottom.This seems to have increased the possibility of simultaneously realizing the conservation of bluefin tuna stocks and the continuation of set net fishing.
According to Tokyokaiyo University, Associate Professor Akiyama and his colleagues have divided into three stages: selection of large and small bluefin tuna fish, a method of letting small bluefin tuna fish escape alive, and selection of small bluefin tuna and other species of fish such as yellowtail. Developed the technology.
In the selection of large and small bluefin tuna fish, it was found that when a selection net with a mesh side of 1 mm was attached to the set net, large fish could be caught by the set net and small fish could be left in the set net. ..
It is known that if the bluefin tuna that have entered the fixed net are scooped up with a net and escaped, most of them will die, but if the fixed net is provided with an openable emergency outlet and driven into this area, more than 8% survived.
However, since other species of fish such as yellowtail will escape as it is, a safe net connected to the fixed net by a narrow passage was installed in the back of the fixed net and left for 3 days. , Small bluefin tuna fish and Spanish mackerel were found to remain in the set net.
The amount of bluefin tuna is drastically reduced, and it is worried that it will become extinct.For this reason, measures have been taken to limit the catch of small fish weighing less than 30 kg to half of the conventional amount in the waters near Japan.There are about 600 large set nets operating in Japan, but since it is a fishing method that catches various species of fish at once, there is a possibility that the operation will have to be stopped when the catch of small bluefin tuna fish reaches the upper limit. Is out.
