Prior to the 1982–83 El Nino, California sea lion (Zalophus californianus) populations in the California Channel Islands were recovering from low abundance levels that resulted from unregulated exploitation and indiscriminate killing which began in the 1800s and continued through the late 1930s (Bonnot 1937; Bartholomew 1967; Stewart et al., in press). There has been an increasing trend in sea lion abundance on the California Channel Islands since 1958 (Bartholomew 1967; Odell 1971; Le Boeuf and Bonnell 1980; Stewart et al., in press). Based upon counts of pups born between 1971 and 1981, the sea lion population at San Miguel Island increased at about 5% annually (DeMaster et al. 1982). The population in the Channel Islands is estimated to number 87 000 animals (Boveng 1988).
