[CINC] Humpbacks

[Ron Dreher]

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Beloved cetaceans: Humpback whales' return to area waters follows long
absence I 


 

May 11, 2008 12:00 AM

For many, the humpback whale is the most beloved of cetaceans. This is the
singing whale of song and legend, the acrobatic whale, the friendly whale,
the character.

Until fairly recently, however, the humpback was seldom seen in the Santa
Barbara Channel. A look at whaling records reveals the most likely cause:
During the period 1956 through 1965, 841 humpbacks were killed off
California. From 1966 through 1969, however, none was killed -- not because
the whalers didn't try, but because they couldn't find any to kill.

Anita Daugherty, who wrote a book on marine mammals for the California
Department of Fish and Game in 1972, observed, "The last catches of the
endangered blue whale, never large here, were made in 1965, as were those of
the much more abundant humpback."

This might have been an epitaph for the humpback in California. However, in
1970, legislation was passed protecting eight species of so-called great
whales -- the largest ones -- and by the end of 1971, whaling had ended in
America except for some subsistence hunting by American Indian peoples. In
1972, the Marine Mammal Protection Act was passed, giving protection to all
species of marine mammals.

I clearly remember a pair of humpbacks that appeared every summer off the
west end of Santa Cruz Island. This was in the mid 1960s. Then one summer,
they never showed up again. Since then, humpbacks were reported here and
there off California, but it was not until 1987 that they began appearing in
large numbers in the Santa Barbara Channel. Blue whales followed a couple of
years later. By 1992, both species were so prevalent that the whale watch
industry could offer year-round excursions.

The present stock of humpbacks is estimated at nearly 1,400 animals.
Considering that 841 humpbacks from a population once considered "much more
abundant" were killed off California in a 10-year period, it seems clear
that whalers nearly exterminated this species off California.

The present regional stock, one of several worldwide, ranges from Central
America and Mexico in the winter to California, Oregon and Washington from
spring to fall. The calving grounds for this stock are most likely in the
southern part of the range. Virtually all of the humpbacks seen here are
adults and juveniles -- a few quite young.


 

Humpbacks come here to feed, preying on small schooling fish such as
anchovies and sardines, and on krill, shrimp-like crustaceans about the size
of earwigs. They plunge into concentrated schools of prey, mouths agape,
then close their mouths, forcing the food-laden water through their
brush-like baleen plates, a bit like licking cookie crumbs off a mustache.
Humpbacks, in fact, are mysticetes, literally meaning "mustache whales."

An interesting phenomenon occurs while humpbacks are feeding. This is
difficult to see unless many whales are observed or a video is played back
in slow motion. When the lower jaw is extended for a gulp, the water fills
the throat, expanding a row of pleats to allow a greater volume of water to
be ingested.

As this occurs, the lower jaw appears to widen, much like a catcher's mitt
opening up. Some researchers believe that the lower jaw may hinge at the
point of the chin, making a much wider scoop. Recordings made of feeding
humpbacks sometimes catch a loud pop, which the researchers believe may be
the jaw opening up. At any rate, when the lower jaw is fully open, it
certainly doesn't look as though it would close completely into the upper
jaw.

The much showier and more obvious antics of humpbacks, including breeching,
lobtailing and flipper slaps, make this species very popular with whale
watchers. And for boats with hydrophones, listening to the underwater
vocalizations can be a real treat. Humpbacks have been in the channel since
February, along with gray whales, so now is a good time to see them.

Peter Howorth is director of the Santa Barbara Marine Mammal Center.

 

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