I’m writing in regard to your story “Whale of a show off Moonstone Beach,” by Steve Swenson, on Page 5 of the May 9 Cambrian.
His account was interesting and stirred up some excitement. However, his last three paragraphs contained some misinformation, or at least “mixed-up” information.
My qualifications to comment are that I manage the Morro Bay Museum of Natural History (since 2005, with State Parks since 1989) and work as a naturalist and deckhand on local whale watching boats (since 2007).
The reported sizes for gray and humpback whales were correct as probable maximum lengths, but the migration periods were jumbled together. Here is the correct information.
Gray whales migrate south along the San Luis Obispo/Central California coast from the end of December through early to mid-February.
February is a transition month, with both southbound and northbound gray whales seen. By mid- to late February, most of the gray whales are headed north. By late March or April, mother-calf pairs appear, frequently in shallow water (40-80 feet) less than a half-mile from shore.
Most of the gray whales are gone by May, but they can sometimes still be seen for a few more weeks in May. Their endpoints are: Baja California (Mexico) for mating and birthing in the winter, and the waters between Alaska and Siberia (Bering and Chukchi Seas, Arctic Ocean) for feeding in the summer.
The local population of humpback whales comes to California waters from May to October to feed. They are seen from the Santa Barbara Channel north to the Farallon Islands off San Francisco, and occasionally as far north as Oregon.
By early November, most humpbacks have left Central California waters for the waters off Costa Rica and Central America, where they spend the winter. Humpback whales occur in several distinct populations. Humpbacks that spend the summer in Alaskan waters migrate to Hawaii during winter. There is little or no mingling between these populations in terms of their migratory routes.
Most baleen whales that migrate are moving between warm waters in winter where they mate and breed, to cold northern polar/sub-polar waters to feed.
Humpback whales might feed on schooling perch, but they are much more likely to feed on small schooling fishes such as sardines, anchovies, and (in northern California) herring. They also eat squid, shrimp and krill, a particular kind of schooling shrimp-like creature.
Gray whales are unique among baleen whales in feeding primarily in bottom sediments, where they strain out clams, marine worms and amphipods, another kind of shrimp-like burrowing animal. Perch, which move in smaller schools, would not provide enough nutrition for the effort whales would expend to catch them.
It’s always encouraging to see articles that generate enthusiasm for local wildlife, and it’s even better when the facts are clear.
Rouvaishyana, who only uses a single name, is manager of the Morro Bay Museum of Natural History.