Genetic variability and population decline in Steller sea lions from the Gulf of Alaska

The western stock of the Steller sea lion (Eumetopias jubatus) was listed a s endangered in 1997 due to its decline in numbers since the 1960s. We exam ined haplotypic diversity using nucleotide-sequence analysis of the control region of the mitochondrial DNA (mtDNA) from animals collected in 1976-197 8 from the western and central Gulf of Alaska and compared results to previ ously published data from animals collected in the 1990s from the same geog raphic areas. No significant differences were found in frequencies of haplo types between the two time periods, and genotypic diversity was high for al l populations and time periods studied. It is concluded that, despite reduc tion in numbers, populations in the Gulf of Alaska have not lost appreciabl e genetic diversity, and if populations are allowed to recover, no long-ter m change in fitness is expected.