The relation between the construction of the trap for the Puffer fish and the fishing mechanism that it has was investigated. The relative efficiency of the trap was calculated with both the data of the trap width and the catch of fish. The calculated selectivity of the trap was compared with that estimated by the probability model for the Puffer trap fishery, taking into account the fish turning motion in a trap entrance. The obtained length selectivity for the puffer Lagocephalus wheeleri approximately agreed with the theoretical values. The length selectivity of the trap of the puffer Lagocephalus gloveri showed higher values than the theoretical values. The selectivity of the trap calculated on the probability model seemed to be influenced by the length of the Puffer fish.
We confirmed that the fishing mechanism of the trap for the Puffer fish depends on the behaviour of the fish inside of the trap entrance, but the behaviour of the fish seem not to be necessary uniform.