Prevalence of skin pseudotumors in three species of pleuronectids in Notsuke Bay, Hokkaido, northern Japan

Pleuronectes schrenki has been reported to bear skin pseudotumors in Notsuke Bay, Hokkaido, northern Japan, but the past identification of the fish from this bay has remained uncertain. Thus, pleuronectids were collected from the bay and, after exactly identified, they were examined for the presence of skin pseudotumors. Three species of the genus Pleuronectes (P. schrenki, P. obscurus, and P. pinnifasciatus) were collected, and prevalence of skin pseudotumors varied between these species. The disease was most frequently found in P. obscurus, but was very rare in P. schrenki and P. pinnifasciatus, which suggests that the fish reported previously as P. schrenki from the bay were not the species but P. obscurus. In P. obscurus, prevalence of the disease was lower in larger fish (150-236 mm in standard length [SL]) than in smaller fish (65-149 mm SL).