Migratory destinations of humpback whales that feed off California, Oregon and Washington

Abstract

The migratory destinations of humpback whales that feed off California, Oregon and Washington were determined using photo-identification. Fluke photographs of 594 individuals were taken between 1981 and 1992 and compared to collections from 9 wintering regions in the North Pacific: Ogasawara (162) and Okinawa (17) islands of Japan; the Big Island and Maui (634 for both) and Kauai (384) of Hawaii; the Revillagigedo Archipelago (450), the mainland coast (383) and Baja Peninsula (471) of Mexico; and Central America (31). A total of 160 matches were found to 6 central and eastern North Pacific wintering regions, with most from Central America, Baja, and mainland Mexico. Of whales identified off Central America, 84 % were resighted off California-Washington; this high rate of interchange suggests that whales in these tropical waters appear to be comprised entirely of animals from the California-Washington feeding aggregation. Humpback whales seen off Central America were resighted disproportionately off southern California while those from mainland Mexico tended to be seen off northern California-Washington. From 157 same-season migratory transits documented, the shortest were 29 d to Baja and 56 d to Costa Rica and the longest distance was 5322 km. Of the California-Washington whales with known sex, the proportion of males identified at a wintering region was significantly higher than females (2.2:1, p < 0.05).