Distribution of Midwater Fishes among Deep-Water Basins of the Southern California Shelf

Abstract

Depressions in the relatively narrow continental borderland off southern California provide a near-shore deep-sea habitat extending among the California Islands from Point Conception southward to beyond the Mexican border.Geologic instability of this area has resulted in a tectonic multiplication of ridges delimiting 14 basins, which may be classified as to their depth, physicochem ical properties, and distance from shore (Emery, 1960).Ocean currents in the borderland are complex and marked by the presence of surface eddy patterns.One major current system flowing into the borderland, the southerly moving California Current, is part of the great clockwise circulation of water in the North Pacific Ocean.Subsurface currents derived from the California Current influence the development of eddy systems.A permanent eddy, including the northward-flowing southern California Counter Current, is established over the deep offshore basins and Santa Cruz Basin.Below 500 meters, a deeper counter current flows gradually northward throughout much of the borderlands and approaches the surface during late summer and fall.From spring to fall the California Current predominates, while in late fall through winter the area is influenced by the deeper counter current and local cooling (Sverdrup et al., 1942;Reid et al., 1958).