STATUS AND TRENDS OF WHITE ABALONE AT THE CALIFORNIA CHANNEL-ISLANDS

The white abalone Haliotis sorenseni occupied rocky reefs in high dens ities around the California Channel Islands at depths of 26-65 m in th e early 1970s. By 1981, white abalone densities had declined two order s of magnitude, and the species had virtually disappeared by the early 1990s. From April 1992 through December 1993, we searched 30,600 m(2) of suitable habitat at 15 locations known previously to support the w hite abalone. We found three live individuals (mean density, 0.0002/m( 2); SE, 0.0005). All three were near the maximum size common for the w hite abalone. At average densities, an equivalent search in the 1970s would have revealed 6,120-30,600 adults. Fishery landings reflected th is population collapse. Annual commercial landings averaged 41 metric tons in 1971-1976, peaked abruptly at 65 tons in 1972, then plummeted to 0.140 ton in 1981; landings averaged only 0.153 ton from 1991 throu gh 1994. Recreational landings, never numerous, virtually ceased after 1983, During the 1992-1993 survey, we also found 119 empty white abal one shells, 42-195 mm long, at a mean density of 0.0085/m(2) (SE = 0.0 065). The last major white abalone recruitment event at the California Channel Islands was apparently in the late 1960s. Survivors of legal harvest in the 1970s were so few and so sparsely distributed that no s ignificant reproduction has occurred since then. The California white abalone population appears to have collapsed in the 1970s and is appro aching extinction from natural causes some 20 years after intense expl oitation ended.