Fishing Technology Division, National Research Institute of Fisheries Engineering, Fisheries Research Agency, Hasaki, Ibaraki 314-0421, Japan
To investigate ghost fishing by lost traps for the red queen crab Chionoecetes japonicus, comparative fishing experiments with commercial traps were conducted in the sea area to the west of the Oki Islands in the Japan Sea. Catches with fish bait (mackerel) were compared both with catches from traps containing dead crabs (red queen crab) and without bait in 1992 and 1998. Male crabs were not caught by the traps containing dead crabs, but females were caught in small numbers. Unbaited traps caught a few crabs. Since dead decapods in traps can greatly reduce catches of conspecifics, catches with fish bait were compared with catches with fish bait plus dead crabs in 2001. Catches of male crabs decreased significantly in traps with fish bait plus dead crabs in all operations. Dead crabs repelled male crabs. On the other hand, females can escape from commercial traps by passing through the mesh because of their smaller size. Therefore, we think lost traps with dead crabs will not continue to attract new crabs. Since there were a few catches even in unbaited traps, however, we cannot exclude the possibility that the lost traps continue to catch crabs.