A temporal, sex-specific occurrence pattern among white sharks at the south Farallon Islands, California

Based on 239 observations of 22 known-individual white sharks from 1987 to 2000, we report a temporal, sex-specific occurrence pattern among adult white sharks at the South Farallon Islands (SFI), California: individual males may occur every year, whereas individual females show a biennial occurrence pattern, being recorded every other year at most. This sex-specific occurrence pattern implies a 2-year reproductive cycle, resulting in a lower reproductive potential than previously thought, which has important implications for the conservation of this species. These results also suggest that female white sharks may travel significant distances in the North Pacific Ocean during a biennial reproductive cycle to give birth, whereas copulation may occur closer to northern California, allowing males to return annually to SFI.