Microhabitat use of Pseudocharopinus markewitschi (Gusev, 1951) (Copepoda: Lernaeopodidae) on the mottled skate, Beringraja pulchra (Liu, 1932): Does biased occurrence on the dorsal side of the pelvic fin imply a safety zone?

Abstract

The mottled skate Beringraja pulchra is a coastal fish caught by gillnet and bottom trawl fisheries in Hokkaido, Japan. We recently found a parasitic copepod identical to Pseudocharopinus markewitschi (Gusev, 1951) on this commercially important fish. A total of 109 host individuals caught off the coast of northern Hokkaido, Japan, were examined for adult females of this copepod, and 67 cases (61.5%) of infection comprised with 31 cases (67.4%) of 46 males and 36 cases (57.1%) of 63 females were found. The parasite specimens (n = 229) were recovered mainly from the dorsal side of the pelvic fin (n = 168, 73.4%), followed by the claspers (n = 32, 14.0%). The mottled skate is thought to spend most of its lifetime lying in sand or crawling on the seafloor. Therefore, the biased infection to the dorsal side of the pelvic fin may imply that site selection favors less susceptible for disturbances resulting from such host-specific behavior.