The movement and growth patterns of young-of-the-year black rockfish (Sebastes melanops) inhabiting two rocky intertidal areas off Northern California

Black rockfish (Sebastes melanops) recruit to shallow coastal habitats at four to six months of age. Habitats utilized include kelp and eelgrass beds, estuaries, and tidepools. Black rockfish are unique among Sebastes spp. in that they are found in tidepools as juveniles. The objective of this study was to determine if young-of-the-year black rockfish exhibit site fidelity and homing behavior while inhabiting rocky intertidal areas. In addition, growth rates, recruitment, and use of rocky intertidal areas as nursery grounds were examined. This research was conducted off northern California at two rocky intertidal sites within Redwood National and State Parks during 2007 and 2008. To test for site fidelity and homing behavior, fish were marked subcutaneously with unique color coded tags and displaced at distances ranging from 0 to 258 m from their original pool of capture. Site fidelity was observed in 38 percent of all fish tagged. Homing behavior was noted in 61 percent of the fish recaptured. Homing behavior was observed at all displacement distances used. Fish displaced 258 m, however, displayed the weakest homing behavior. Mean growth in length ranged from 0.204 to 0.343 mm d-1 between years. Throughout the residence period, growth rates increased. Recruitment varied highly among sites and between years. In 2008, a 34-fold increase in recruitment strength was noted compared to 2007. Within each year the relative abundance of black rockfish was highest during the months of June and July, with peak abundance occurring between mid-June and early-July. Maximum residence time observed for a recaptured fish was 67 d. Length of residency was similar among sites and between years. Results indicate that young-of-the-year black rockfish display site fidelity and homing behavior while inhabiting rocky intertidal areas. Furthermore, these findings strongly indicate that they use rocky intertidal areas as nursery grounds. This research provides important information for the management of rockfish and for future deliberations concerning marine protected areas off northern California.