Environmental Significance of Fin Erosion in Southern California Demersal Fishes

The Dover sole was the species most often affected with eroded fins. Prevalence of the disease was highest on the Palos Verdes shelf, the site of a major municipal waste water discharge. Fin lesions in this species were characterized by a minimal inflammatory response and by the absence of associated microorganisms. The fins most frequently affected were those most often in contact with bottom sediments. Diseased specimens from the shelf had higher levels of total DDT and a tendency toward higher levels of total PCB in muscle tissue and a greater liver to body weight ratio than did unaffected specimens from the same area. Laboratory exposure of M. pacificus to contaminated sediments from the shelf resulted in the development of fin erosion. Chlorinated hydrocarbon levels and liver weight to body weight ratios in the exposed fish approached those measured in fish from the shelf. These studies suggest that fin erosion in M. pacificus is caused by exposure to contaminated sediments and that the role of chlorinated hydrocarbons should be tested directly in future experiments.