The perilous condition of white abalone Haliotis sorenseni, Bartsch, 1940

The white abalone, Haliotis sorenseni, seems to be on the brink of extincti on. We searched 107,650 m(2) of white abalone habitat at 39 locations aroun d the California Channel Islands, the species' historical center of abundan ce. At SCUBA depths, 25-42 m, where mean densities in the 1970s were 2,000 to 10,000 white abalone per hectare, we found a mean density of 1.6 +/- 0.5 ha(-1) in the early 1990s. Surveys conducted by submersible in 1996 and 19 97 at depths of 27-67 m revealed the same extremely low population densitie s (1.0 +/- 0.4 ha(-1)), in a remarkably narrow band of suitable habitat on deep reefs, and demonstrated the suitability of the research submersible DE LTA for abalone surveys. Following a 270 metric ton commercial harvest in t he 1970s, landings of white abalone virtually ceased. No fishery-independen t population assessment was made until 1992 to 1993, and the fishery remain ed open until 1996. The management scheme, based on a minimum harvest size of 153 mm and a closed season during spawning, apparently failed to protect adequate spawning stock density. The population has not recovered from the harvest, and the survivors are currently dying of old age. Spontaneous rec overy is highly unlikely, even in the absence of continued harvest. Active management intervention will be required to prevent extinction and to resto re the species to a viable status. We identify a program of capture rearing and refugia-based management, with a public education component and using existing governmental processes, to restore the white abalone population.