Substantial changes have occurred in assemblages of nearshore reef fishes in the Southern California Bight during the past two decades. These have included large declines in abundance of the majority of species. In addition, composition of assemblages studied along the coast near Los Angeles, CA has shifted from dominance by northern to southern species. Since the early 1970?s, the proportion of species in the assemblage that were of the cold-water, northern type has dropped by about half, while the proportion of southern, warm-water species has increased. These changes in abundance and species composition are associated with a climate regime shift that took place in 1976-77 that resulted in warmer water temperatures and lower productivity of the coastal marine ecosystem off Southern California.