Temporal variability in the environmental and geographic predictors of spatial-recruitment in nearshore rockfishes

Geography and habitat availability may be key drivers underlying spatial patterns of larval supply and recruitment success of nearshore marine fishes, but they are poorly understood. We assessed spatial recruitment patterns of nearshore young-of-the-year Pacific rockfishes Sebastes spp. in kelp forest and eelgrass meadow habitats from 2004 to 2014 on the west coast of Vancouver Island, British Columbia. Our sites varied in habitat area, wave exposure, sea surface temperature, and distance from the open coast. We observed recruitment of several species of rockfish, including black rockfish S. melanops, bocaccio rockfish S. paucispinis, and a complex of copper, quillback, and brown rockfishes (S. caurinus, S. maliger, and S. auriculatus; CQB). For black rockfish, the species recruiting in highest abundances, we found that although the environmental variables that predicted recruitment were temporally variable, in some years recruitment was higher at sites with colder sea surface temperature, higher tidal velocity, higher fetch, and higher salinity. In contrast, CQB rockfish recruitment was consistently higher at sites with higher fetch but lower tidal velocity, and this relationship was stable through time. Interactions among environmental variables and habitat area explained the counterintuitive observation of higher recruitment in smaller eelgrass meadows but larger kelp forests. Moreover, sites in or on the boundary of a rockfish conservation area experienced the lowest recruitment during an exceptionally strong black rockfish recruitment event in 2006. These results suggest that temporal variability in the ability of environmental variables to predict the spatial distribution of young-of-theyear rockfishes should be considered in models of population connectivity.