Effects of Pectenophilus ornatus (Copepoda) on the biomass of cultured Japanese scallop Patinopecten yessoensis.

There was a negative relationship between the number of parasitic copepods (Pectenophilus ornatus) and the dry weight condition index of the infected Japanese scallop (Patinopecten yessoensis) cultured in the Tsugaru Strait of northern Japan. The parasite is considered a serious pest of the commercial bivalve in cases of heavy infection.