BLUE WHALES IN CENRAL CALIFORNIA: THE IMPACTS OF WHALING, FOLLOWED BY PROTECTION AND SUBSEQUENT RECOVERY

By Alan Baldridge

 

   Early shore-based whaling at Moss Landing killed only a few Blue whales, as Humpbacks were the major target between 1919-21. International whalers exploited the species on its wintering grounds offshore from Southern Baja California in the 1930's, ending in 1966.

   The first Monterey Bay area sighting in recent times was in September 1970. The growth of Monterey-based fall pelagic birding, including the observing of marine mammals, was first undertaken by various Audubon Societies in the 1960's and 1970's. Later Debi Shearwater (Shearwater Journeys), followed later still by Nancy Black (Monterey Bay Whale Watch), have charted the return of Blues in this region. Blue whales occur regularly from July through early November, with occasional sightings earlier or later. In years of great krill abundance, the Blues respond, becoming common.

   Following several years of ship surveys (National Marine Fisheries Service) and individual photo ID (J. Calambokidis and associates), the California/West Mexico population is now estimated at circa 2000 and is the most robust known, exceeding that in the Southern Ocean. Winter concentrations of "our" animals occur off Southwest Baja California, in the lower Gulf of California and as far south as the far offshore Costa Rica Dome.

   Summer/fall feeding in California occurs first on the Cortez and Tanner Banks off San Diego followed by the Northern Channel Island waters off Santa Barbara, then the Monterey region and the Gulf of the Farallones/Cordell Bank areas off San Francisco north to Sonoma county.

   The first focused research on the Blue whale in our area was that of Moss Landing Marine Laboratories (MLML) Master's student Jill Schoenherr, who studied feeding behavior and ecology during an exceptional fall influx in 1986 of 25 + animals, concentrated along the Canyon rim, 6-7 miles NW of Point Pinos. Currently Dr. Don Croll and associates from UC Santa Cruz (UCSC) and MLML are studying Blues and other baleen whales in relation to upwelling and krill patch formation. They have found the animals to depart quickly once the krill patches are exhausted, but return as soon as they reform.

   In periods of abundance here individuals, often in pairs, venture into the inner Bay off Hopkins Marine Station and Cannery Row, but return quickly to deeper waters. The persistent observer may also observe them from shore in the deep Carmel Submarine Canyon waters from Cypress Point, Pebble Beach, and from Point Lobos State Reserve, during July - September.

   While normally seen singly or in pairs, groups of widely scattered animals may occur in areas of krill abundance.

   Strandings have occurred at Bean Hollow State Park, San Mateo County (skeleton mounted and on public display at the Long Marine Laboratory, UCSC) and between Point Sur and the Big Sur River mouth. Two or three others have occurred in Southern California. Ship collisions are judged to have caused some of these deaths. Blues are often, but not always, encountered during our ACS/MB summer whale watch in late August or early September.

 

Soundings   Special 20th Anniversary Issue   Summer 2000