Comparative fishing trials for Charybdis japonica using collapsible box-shaped and dome-shaped pots

Comparative fishing trials were undertaken with two commercial collapsible pots for the crab Charybdis japonica. One pot was box‐shaped with two slit entrances at the ends, while the other was dome‐shaped with two open funnel entrances. Pots were placed at the bottom of a pond that is connected to Kagoshima Bay. Fishing trials were carried out using a 1‐day soaking time; the bait used was mackerel. The box‐shaped pot had higher catches of crabs and non‐target organisms, but the number of large crabs (carapace width >8 cm) was almost half as many as that caught with the dome‐shaped pot. The catch of non‐target species was also greatly reduced in the dome‐shaped pot, and fish caught were mostly enmeshed in the netting. The reduction in catches of small crabs and non‐target organisms was due to the nature of the dome‐shaped pot's larger mesh size and open entrances, which allowed for escape. The dome‐shaped pot seemed more efficient for harvesting commercial size crabs, while the box‐shaped pot seemed better for removing all crab sizes.