FISH PRODUCTION AND HABITAT UTILIZATION ON A SOUTHERN CALIFORNIA ARTIFICIAL REEF

The feeding habits of fish, their production, and their fidelity to the reef habitat were estimated on and near Torrey Pines Artificial Reef (TPAR) during April-October 1989. Taxonomic and biomass analysis of gut contents and benthic resources suggested that at least 70% of the diet of reef fish was derived from the reef itself and another 20-25% from the ecotone. For most reef fishes, suitable prey was 100 times more abundant in the reef habitat than in adjacent sand habitats. Estimates of somatic production by tagged fish were based on standing stocks, size distribution, and growth rates, and by untagged species, on changes in mean length of a cohort or population biomass over time. Estimated total production of the fish on TPAR was 116 kg, or 649 kg.ha(-1), more than a third of it as gonadal production by the six target species. Production by the sand-bottom fish assemblage, estimated from literature-derived somatic and gonadal production rates and the biomass of trawled fish, was 73 kg hectare year(-1). Calculated reef production was, therefore, about nine times greater than the production of sand-bottom fish. From 30 to 70% of the four species of tagged fish (sheephead, rock wrasse, black perch, and garibaldi) that could be captured by divers were recaptured after 7 months, indicating a high degree of fidelity to the reef. Recapture of 12% of tagged kelp bass via hook-and-line after 7 months and the recapture of five tagged kelp bass of a total of 40 kelp bass caught 1 year later by a sport fishing boat indicate that kelp bass, too, remained associated with the reef for long periods.