Bathynomus (Isopoda:Cirolanidae) Attacking Sharks Caughut in a Gill-net
Baited traps have been developed for capturing commercially important benthic or near-bottom crustaceans. In the Kumano-nada region along the Pacific coast of central Japan, however, the trapping of the important and commercially attractive crustaceans to the bait sometimes failed to capture them due to serious damage of the bait by abundant bathynomids lacking in economic value. The bathymetric records of the bathynomids have been plotted mainly at depths from 200 m to 600 m according to the samples collected by the baited traps set under the continental slope waters. On the fisheries training course by the training vessel ゛Seisui-Maru", bottom gill-nets which were set at a site (the Kumano-nada region) of <special>33°</special>-45'N and <special>136°</special>- 08'E with the depth of 520 m on 18 November 1980 caught an armor shark Dalatiaslicha．This shark, known generally as a deep－sea shark, was already been dead when the gill-nets were reised. But the shark would have been presumably alive when it was caught in the gill-nets judging from the fact that the shark had become tangled in the nets. The shark showed an abdomen swollen abnormally, and anal parts badly damaged. We found a total of 18 individuals of giant isopods Bathynomus döderleini in addition to a snubnosed parasitic eel Gymnosimenchelys leptosomus within its abdominal cavity. The bathynomids and snubnosed eels, contained within the shark's abdominal cavity, were still alive, even on board the vessel. As far as is known, it has been not documented that the bathynomids attack live fish. So we believe that the bathynomids entered the shark's body shortly after the shark was killed due to tangling in the nets, and then they entered the abdominal cavity by destroying the anal parts of the shark.
- 三重大学水産学部研究報告 = Bulletin of the Faculty of Fisheries, Mie University
三重大学水産学部研究報告 = Bulletin of the Faculty of Fisheries, Mie University 8, 11-17, 1981-10-01