The prevalence of fish anomalies and parasites was low and incidences were scattered throughout the SCB. A total of 557 (0.9%) of 61,687 fish had anomalies or parasites (Table IV-16). Anomalies were found in 22 (16%) of the 140 species. Anomalies and parasites identified in the study included parasites, tumors, lesions, fin erosion, ambicoloration, pigmentation, deformities, and deformities /lesions. Most (88%) of these were parasites. Of the remaining anomalies, tumors were the most abundant, followed closely by lesions, then ambicoloration, deformities, fin erosion, pigmentation, and deformities/lesions. In the survey, 454 (93%) of the 489 fish that had parasites were Pacific sanddab. Similarly, most (88%) of the fish with tumors (26) were Dover sole (23), and most (85%) fish with lesions (20) were speckled sanddab (17). Although all kelp bass collected had parasites, this only represented two individuals (Table IV-16). Similarly, only 1 of 6 black eelpouts (Lycodes diapterus) had parasites, but it was enough to rate this species second highest in percent of anomalies (17%). Otherwise, among fish species with total catches greater than 10, percent anomalies ranged from 0.03-3.1% to. Among these, California skate (Raja inornata;3.1%) had 2 parasitized fish out of 64, California halibut (3.0%) had 5 parasitized and 1 ambicolored fish out of 198, and Pacific sanddab (2.7%) had 454 parasitized fish, 4 ambicolored fish, 2 fish with deformities, and 1 individual characterized with a deformity or lesion.
Table IV-16. Number of fish by species with different anomaly types collected at depths of 2-476 m on the southern California shelf, July-October 2003.
Anomalies occurred in 38.2% of the area of the mainland shelf of southern California (Table IV-17). Among regions, they were most prevalent at cool and warm island regions (81.3 and 84.6%, respectively), followed by the central and southern mainland regions (52.8 and 41.2%, Parasites occurred in 32.0% of the area, followed by ambicoloration (6.5%), tumors (3.6%), lesions (2.0%), deformities (1.7 %), pigmentation (0.9%), deformities/lesions (0.9%), and fin erosion (0.5%). Parasites were the most widespread anomaly at inner and outer shelf large POTWs (both 100%), middle shelf islands (83.3%), and middle shelf large POTWs (64.0%). Tumors were most prevalent in middle shelf small POTWs (25.0%), middle shelf islands (16.7%), and middle shelf large POTWs (12.0%; Table IV-17; Figure IV-13). Ambicoloration was most widespread (33.2%) at inner shelf large POTWs (66.7%), outer shelf islands (25.0%), and the mainland middle shelf (15.4%; Table IV-17; Figure IV-14).
Table IV-17. Percent area by subpopulation of fish with different anomaly types collected on the southern California shelf and slope at depths of 2-476 m, July-October 2003.
Figure IV-13. Distribution of fish anomalies on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003.
Figure IV-14. Distribution of external parasites of fish on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003.
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