The gray whale (Eschrichtius robustus) was first known to science on the basis of a subfossil skeleton from Sweden described by Lilljeborg in 1861. The family and genus names refer to the Danish zoology professor Daniel Eschricht and the species name means “strong” or “oaken” in Latin.
Sighting Cues: High, bushy, heart shaped blow up to 15 feet (4.6 m) high, in some cases blow might be V-shaped. The fluke will often be lifted out of the water prior to a deep dive
Description: Intermediate in size and girth, slimmer than right whales but more rotund then most rorquals, appear torpedo-shaped when viewed from above. The dorsal hump is followed by series of 6-12 “knuckles”. The flippers are relatively short and paddle shaped, with rounded margins and pointed tips. The flukes (tails) are broad, often spanning more than 9 feet (3 m) wide. Gray Whales have the fewest baleen plates of any whale species, with 130-180 yellowish white plates on each side of the mouth.
Size: 36-50 feet (11-15 m), ♂ slightly smaller than ♀; maximum body weight about 99,000 lbs (45,000 kg)
Behavior: Migrating gray whales move steadily in one direction, breathing and diving in predictable patterns. They commonly travel alone or in small unstable groups, although large aggregations can occur on both the feeding and breeding grounds. Except for mother-calf pairs, associations between individuals are relatively fluid. Breaching and other surface behaviors are common. Feeding gray whales are usually alone or in small groups but normally in near proximity to relatively high numbers (10s to 100s).
Migration/Range: Gray whales (eastern North Pacific population) undertake one of the longest annual migrations of any mammal, traveling some 9,300-12,500 miles (15,000-20,000 km) round trip. By late November, most whales are moving south from summer feeding areas (Chukchi, Beaufort and the northwestern Bering Seas) to winter calving areas (the west coast of Baja California, Mexico, and the southeastern Gulf of California). The northward migration begins about mid-February and most whales arrive to the summer feeding grounds between May and June.
Mating season: late November to early December, coincides with the onset of the southward migration
Gestation: 12 to 13 months
Birth/calving season: mid-January, females produce calves at intervals of 2 years
Litter size: Single calf
Neonate size: 15-16 feet (4.6 - 4.9 m) long, 1500-2000 lbs (680-920 kg)
Age at Weaning: 7-9 months
Age at Sexual Maturity: 6-12 years of age
Lifespan: unknown, estimated 40-80 years
Diet: primarily suction-feeders, consuming benthic amphipods on or near the seafloor; sometimes known to consume cumaceans, mysids, shrimp, mobile amphipods, crab larvae and herring eggs.
Threats: entanglements in fishing gear, environmental degradation including exposure to contaminants and disturbance by shipping and noise (e.g. seismic surveys) related to offshore oil and gas development, (climate change on gray whales and their habitat, especially the notable reduction of sea ice and increasing water temperatures in the Arctic, yet to be determined)
IUCN Status: Western North Pacific population: "Critically Endangered" with an estimated 130 individuals; Eastern North Pacific population: "Least Concern" with about 20,000 individuals
Interesting Fact: In May 2010, a gray whale was observed in the Mediterranean Sea off Israel and the same individual was sighted again a month later off Barcelona, Spain. It is impossible to know if this record of a single individual is indicative of a mounting reoccupation of the historic range (especially in light of receding sea ice in the Northwest and Northeast Passage) or simply represents an extraordinary event.