FISHERY BULLETIN: VOL. 75, NO. 3 



sole <120 mm SL also had eroded fins. These ob- 

 servations suggested that Dover sole with fin 

 erosion caught in the vicinity of the Orange 

 County outfall could have migrated from the 

 Palos Verdes shelf (Mearns and Sherwood 1974). 

 Since the increase had occurred 13 mo after the 

 depth of discharge off Orange County had been 

 changed from 20 to 60 m, within the range of the 

 Dover sole, one objective of this study was to test 

 the hypothesis that the diseased fish collected off 

 Orange County had migrated from the Palos 

 Verdes region and that the disease did not orig- 

 inate in the Orange County area. Since collections 

 on the Palos Verdes shelf contained the highest 

 percentage of Dover sole with fin erosion and the 

 shelf was also the site of highest bottom sediment 

 contamination by total DDT, we attempted to use 

 this contamination as a tag of exposure to the 

 JWPCP discharge area. Reported values for the 

 biological half-life of DDT compounds in fish gen- 

 erally range from about 1 to 5 mo (Buhler et al. 

 1969; Grzenda et al. 1970; Hansen and Wilson 

 1970; Macek et al. 1970). Since the Orange County 

 discharge site is about 35 km to the south of the 

 JWPCP discharge area, it is possible that move- 

 ment over this distance could occur before a sig- 

 nificant fraction of the accumulated DDT residues 

 had been depleted. 



In Dover sole, external signs of the disease were 

 restricted to the fins. The noninflammatory na- 

 ture of the lesions and the absence of any demon- 

 strable organisms associated with the lesions, as 

 determined by histological examination, suggest 

 that the disease is not the result of an infectious 

 process (Klontz and Bendele 3 ). If chemical agents 

 are involved, then it is possible that concentra- 

 tions of these agents in tissues might reflect their 

 involvement in disease development. A second ob- 

 jective of this study was to explore the role of 

 chlorinated hydrocarbons in the fin erosion dis- 

 ease by determining if there were differences 

 between the levels of total DDT and total PCB 

 in muscle tissue of Dover sole with and without 

 eroded fins. 



SAMPLING AND ANALYSIS 



Fish analyzed in this study were subsamples of 

 collections made during routine trawl monitoring 



surveys by the County Sanitation Districts of Los 

 Angeles and Orange counties. During 1974, up to 

 four trawl series were conducted off the Palos 

 Verdes Peninsula and Orange County (Figure 1). 

 The trawls off Orange County were conducted 

 with a Marinovich semiballoon otter trawl with a 

 7.6-m (25-ft) headrope and a 1.3-cm (0.5-in) 

 stretch mesh cod end liner. Hauls off Palos Verdes 

 were made with a net of identical dimensions but 

 of heavier construction and otter boards. 4 The 

 nets were towed at a speed of 1.3 m/s (2.5 knots) 

 and remained in contact with the ocean floor for 

 10 min. When the net was brought aboard ship, 

 specimens of Dover sole, with eroded fins (dis- 

 eased) and without eroded fins (unaffected), were 

 removed, bagged, labeled, and immediately 

 frozen. The frozen samples were returned to the 

 laboratory and placed in freezers. 



ORANGE 

 COUNTY 



DEPTHS IN METERS 



FIGURE 1. — Stations off Palos Verdes and Orange County at 

 which Dover sole were collected. 



The following numbers of Dover sole were ob- 

 tained from each of the 1974 quarterly trawl 

 series: winter (December 1973-February 1974), 

 10 from off Palos Verdes; spring (March-May 

 1974), 15 from off Palos Verdes and 5 from off 

 Orange County; summer (June-August 1974), 6 

 from off Palos Verdes; and fall (September- 

 November 1974), 17 from off Orange County. 



The mean and the standard error of the stan- 

 dard lengths for the Palos Verdes samples with 

 (n = 16) and without (n = 15) eroded fins were 



3 Klontz, G. W., and R. A. Bendele. 1973. Histopathological 

 analysis of fin erosion in southern California marine fishes. 

 South. Calif. Coastal Water Res. Proj., Rep. TM 203. 



4 This net was constructed for the Coastal Water Project by 

 J. Willis, Morro Bay, Calif. 



514 



