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California Sea Otter's Life-and-Death Struggles : Infant Mortality, Oil Spills Threaten Ocean Mammals

July 06, 1986|ALLAN PARACHINI | Times Staff Writer

MONTEREY — It is late afternoon on Fisherman's Wharf in Monterey harbor and two tourists with a Midwest sound to their voices stand on a narrow expanse of planking behind Abalonetti's Restaurant, joining an off-duty waitress watching two brown blobs floating in the water below.

Even to the uninitiated, the shapes are easily recognizable as a female sea otter and her newborn pup. The mother otter swims, floats, dives and feeds close by the pup, returning to the surface often with fish apparently filched nearby.

Every so often, she reaches out with her mouth to bring her pup close as she floats, characteristically lying on her back, with the meal spread out on her abdomen. Dutifully, she repulses marauding gulls attempting to steal her food and harass her young.

On this afternoon, with no fewer than 11 sea otters resting, feeding and playing within view of the wharf, it does not take long for spectators to notice that there is something terribly wrong with the otter's display of parental affection.

The pup is not moving and, when binoculars are brought into play, it can be seen that the little creature's face is in the water. The female otter is fastidiously caring for a dead child, behavior that is not uncommon among this mammalian species.

Mounting Concern

Why otter pups die is unclear, but the mortality of the young is partly responsible for concern over the otter's continuing viability--concern that has been building almost continuously since 1976 when the endangered sea otter, which had recovered to 1,400 to 1,500 on the California coast, went into decline again. The population now numbers 1,200 to 1,300.

A female sea otter may care for a dead pup for as long as three weeks until the little carcass finally sinks--a development experts say often appears to profoundly confuse the mother.

About 18 hours after the scene was first observed here, this is precisely what happens. It is the following morning, with the mother and dead young still bobbing off Fisherman's Wharf. The mother grabs her pup by the head, pulling it toward three or four other otters frolicking in the water just off a slender strip of beach next to the quay.

For half an hour or so she does this--observed this time not only by spectators, but also by Jack Ames, a California Department of Fish and Game sea-otter biologist who has spent more than 10 years studying the macabre question of how otters die. He concedes that while many otter deaths are understood, much is still unknown about the meld of factors that can kill them.

"What we know about the sea otter would fill a pretty good-sized book," said Dr. Tom Williams, a veterinarian here who has spent 17 years of spare time studying otter biology. "What we don't know about the otter would fill a heckuva big building."

Courting Otters

What is happening in the bay reinforces Williams' point. With Ames watching from shore through a powerful telephoto lens, the pup appears to slip beneath the surface for the last time. The mother pauses and swims away.

Poignant though the moment is, it is not what has drawn Ames' attention. Through binoculars, he has noticed two other otters courting in shallow water. Otters generally are at ease within view of people, but even otters don't normally make love in public.

Yet with the pup's death being played out less than 100 yards away, Ames notices that the territorial male otter and the passing female have begun to mate.

Having made clear his intentions, the male otter grabs the female by the nose, biting hard enough to draw blood and inflict deep wounds. In fact, the condition of such nose scars among older breeding female otters is a key way biologists can determine their ages. It has become more than a passing (though unresolved) concern that pollution-related infections of nose wounds may emerge as a cause of death in female otters of reproductive age.

Recently, said Marianne Riedman, director of otter research at the Monterey Bay Aquarium, scientists have begun to suspect that the female otter has the capacity to delay implantation of the fertilized egg in her uterus, thus affording her a measure of control over when she will give birth.

The aquarium is currently conducting a variety of otter studies, relying largely on observations by teams of volunteer observers.

Riedman noted that even the animal's natural life span is unknown, though it is thought to be 15 to 20 years for females and about five years less for males.

It isn't known, either, how long the delay in implantation can be--or even, for sure, if the capability exists. Births are almost always of a single pup.

In fact, when the rare birth of twins occurred--the phenomenon has been witnessed just once, ironically by Ames--the mother made an instant decision, shoving one pup away to perish in the waves, selecting the other to survive.

'You Can Hear Pups Crying'

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