California Gray Whale
Evolutionary Place
It should be kept in mind, however, that this whale is the most primitive of the living baleen-bearing whales, and it seems to represent the point in the evolutionary sequence from which the two main groups diverged. The California gray whale is the sole survivor of a family of whales which in past eons was represented by many species. It has a smallish head with a limited filtering mechanism. Its dependence on foods which are found only near to shore is considered further evidence that it is primitive. Likewise its need for harbors to calve suggests that it has not lost its dependence on the nearshore habitat, even though it can safely cross the wide Pacific. The extremely restricted and separated distribution pattern of the whale is typical of an old, primitive species which persists either in its preferred ancestral home, or which occupies less desirable habitats into which it was forced by the more successful species. Recently gray whale remains were found in the Netherlands, and it is possible that it was exterminated in European waters by prehistoric whaling prior to the Ice Age.
Gray whale breaching. Photograph by T. J. Walker.
Another gray whale “spyhopping.” Notice the narrow tapering head, typical of the California gray whale. Courtesy of the Scripps Institute of Oceanography.
Geographic Distribution
Today the species is restricted to two distinct populations existing on opposite sides of the Pacific. One herd summers in the Sea of Okhotsk, migrating southward to Korea where, in the open bays, calving takes place in January, February and March. The larger population summers off the coast of Siberia and Kamchatka, migrating clear across the Pacific Ocean to California and then south to the breeding lagoons near Bahia de Sebastian Viscaino, situated on the outer coast of Baja California. A few whales have been noted around the tip of Baja California and in the gulf itself. These are part of a small group which calve in lagoons along the mainland of Mexico just inside the Gulf of California. It has been suggested that the recovery of the species was possible because these lagoons were unknown to whalers. It is, however, unlikely that the whalers continued to whale until they had completely wiped out the populations of the main lagoons. The inability of the species to support intensive whaling suggests both a limited population and an animal with a low reproductive potential. Since 1850 there have been three brief periods of whaling, each separated by about 20 years. Each succeeding period of whaling has been shorter, suggesting that 20 years is not a long enough recovery period.