Study on the fishing performance of an alternative tubular-type pot for the common octopus, Octopus minor, in Korean coastal waters

We aimed to develop alternative fishing gear for catching the common octopus, to decrease the use of bait and operating costs in comparison to commercial net pots. A tubular-type pot was designed, and behavioral responses of the common octopus were experimentally monitored in tank and replicated 10 times to compare fishing performances between 300 experimental and 300 commercial net pots in the coastal sea of Gangjin, Korea. The behavioral responses under experimental conditions included emergence from the mud den, detection of the bait on the pot surface, and entry into the pot (toward the bait). The field experiment results indicate that numbers and weights of the catch during offshore fishing were 703 (56.0 kg) and 795 (86.3 kg) via tubular-type and net pots, respectively. The catch per unit effort (CPUE) for the number and weight of the tubular-type pot from 10 trials were 0.23 individuals/pot and 18.87 g/pot, respectively; and weight for the net pot were 0.27 individuals/pot and 28.77 g/pot, respectively. No significant difference was noted between the CPUE in catch number for tubular-type and net pots (Kruskal–Wallis test, p=0.305 > 0.05); however, the CPUE by weight was significantly higher using net pot than tubular-type pot (Kruskal–Wallis test, p= 0.01<0.05). The amount of bait used during the experimental period for the tubular-type pots were 1/3.4 less than that of the commercial net pot. Therefore, fishing operating cost for common octopus was reduced using tubular-type pot.