Abstract
We examined the dominant patterns of variability in the fish fauna of the southern C alifornia C urrent based on a principal component ( PC ) analysis of the C alifornia C ooperative O ceanic F isheries I nvestigations ichthyoplankton data set, 1951–2008. Eighty‐six taxa were analyzed, including all ecologically dominant fish species, both exploited and unexploited. The first three PC s accounted for 20.5, 12.4 and 6.8% of the variance of the data, respectively (total: 39.7%). Each was dominated by taxa from particular adult or larval habitats. PC 1 predominantly represented the coherent response of 24 mesopelagic taxa from 10 families and was most highly correlated with long‐term trends in midwater oxygen levels. PC 2 was dominated by six of the seven most abundant ichthyoplankton taxa in the region, predominantly C alifornia C urrent endemics including key pelagic species (northern anchovy, P acific sardine and P acific hake), rockfishes (genus S ebastes ) and two midwater taxa. It was correlated primarily with sea surface temperature and exhibited a significant declining trend. PC 3 was dominated by coastal and reef‐associated fishes with predominantly southerly affinities. It was positively correlated with sea surface temperature and sea level height, a proxy for diminished flow of the C alifornia C urrent. The taxa dominating PC s 2 and 3 mostly spatially co‐occur as ichthyoplankton. These results suggest that fish assemblages in the C alifornia C urrent are predominantly influenced by environmental forcing of their ocean habitats as adults or larvae, or both.