A group of gray whales (Eschrichtius robustus) in the Northeastern Gulf of California, Mexico

摘要

Gray whales (Eschrichtius robustus) spend summer in the Bering, Chukchi, and Beaufort seas and winter in western Mexico. In Mexico, they occur mostly in coastal lagoons along the western shore of Baja California, but some individuals reach the Gulf of California (Leatherwood et al., 1982), where they have been recorded throughout (Vidal et al., 1993). It has been suggested that, in the northern Gulf of California and the Midriff Islands region, gray whales exploit rich, localized patches of food (Tershy and Breese, 1991); however, only 11 reports of living gray whales exist from this area, 5 of which correspond to the Midriff Islands region (Table 1, Fig. 1). In addition to sightings of living gray whales in this area, a stranded gray whale has been reported from 16 km southeast of Golfo de Santa Clara (Brownell, 1971). Although survey eftbrts have been scant and intermittent, records available (Table 1) suggest that gray whales are rather rare north of the Midriff' Islands. For example, Silber et al. (1994) surveyed 1,715 km from boat and 1,521 km from aircraft, recording 225 mysticetes, only 3 of which were gray whales. Vidal et al. (1987) recorded only 1 gray whale among 164 mysticetes in their cruise around the northern Gulf.