GRAY WHALE (Eschrichtius robustus): Eastern North Pacific Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE The gray whale formerly occurred in the North Atlantic Ocean (Fraser 1970), but is currently only found in the North Pacific (Rice et al. 1984). The following information was considered in classifying stock structure of gray whales based on the Dizon et al. (1992) phylogeographic approach: 1) Distributional data: isolated geographic distribution in the North Pacific Ocean; 2) Population response data: increasing in the eastern North Pacific, unknown in the western North Pacific; 3) Phenotypic data: unknown; and 4) Genotypic data: unknown. Based on this limited information, two stocks have been recognized in the North Pacific: the Eastern Pacific stock, which breeds along the west coast of North America (Fig. 30), and the Western Pacific or "Korean" stock, which apparently breeds off the coast of eastern Asia (Rice 1981). Most of the Eastern North Pacific stock spends the summer feeding in the northern Bering, Chukchi, and Beaufort Seas (Rice and Wolman 1971). However, gray whales have been reported feeding in the summer in waters off of Southeast Alaska, British Columbia, Oregon, and Washington. The whales migrate near shore along the coast of North America from Alaska to the central California coast (Rice and Wolman 1971) starting in October or November. After passing Point Conception, California, Rice et al. (1984) reported the majority of the animals take a more direct offshore route across the southern California Bight to northern Baja California. The Eastern North Pacific stock winters mainly along the west coast of Baja California. The pregnant females assemble in certain shallow, nearly landlocked lagoons and bays where the calves are born from early January to mid-February (Rice et al. 1981). Interestingly, a small, but increasing proportion of newborn calves have been sighted along the California coast during the southward migration (Shelden et al. 1995). The northbound migration generally begins in mid-February and continues through May (Rice et al. 1981) with cows and newborn calves primarily migrating northward between March and June along the U. S. west coast.