Escape openings reduce the catch of small North Pacific giant octopus, Enteroctopus Dofleini from fishing basket, Aomori, Japan
2019
Nagano, K. ((Hokkaido University, Hakodate, Hokkaido (Japan). Graduate School of Fisheries Sciences), (Aomori Prefectural Industrial Technology Research Center Fisheries Research Institute, Aomori (Japan))) | Miura, T. | Sakurai, Y.
In octopus fisheries around the coastal water of Tsugaru Strait, Aomori, Japan, mainly fishermen use the octopus fishing basket to catch the North Pacific giant octopus, Enteroctopus dofleini. These baskets catch all size of octopus and fishes, which can't escape from these baskets once they enter. North Pacific giant octopus is very aggressive and they kill and feed other octopuses and fishes inside the basket. In this study, we examined the effect of size of ring is installed with the basket on the escapability of the small octopus below 3 kg by captive experiments. We estimated 53.2 mm as the inner ring's diameter through which 50% of 3 kg octopuses can escape. Subsequently, we installed 55 mm inner diameter rings to the basket to validate the effectiveness of the estimated size. Basket installed with rings had less catches of small octopus (<3 kg), but caught the almost same number large octopuses of ≥3 kg. The use of basket installed with rings in octopus fishery at Aomori is expected to contribute to the conservation of smaller E. dofleini.
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