Shy Seal in a Stormy Sea
Though protected by law, the secretive harbor seal cannot escape controversy or pollution along the Pacific Coast
- Michael Tennesen
- Dec 01, 1990
Staring angrily, Doyle Hanan races his four-wheel drive Jeep across Point Conception, a rugged coastal peninsula 150 miles north of Los Angeles. Ahead, the California Fish and Game biologist can see a helicopter rising and descending over a bluff facing the Pacific Ocean. "That's right where the seals are!" he shouts, referring to a harbor seal breeding site he has been studying for years. As he closes in, the helicopter sets down beside a lighthouse 500 yards from the beach.
Hanan arrives just as a Hollywood film crew steps out of the helicopter. He advises them of the consequences of disturbing the harbor seals - a fine of as much as $10,000 under the Marine Protection Act. But the crew claims they haven't seen any seals; they were merely photographing the water for a background for a movie.
Intentional or not, a disturbance such as a roaring helicopter over their heads could easily cause pregnant seals to abort their young, says Hanan. The scientist's concern seems to go beyond academic fascination, but he's not the only one who takes a passionate interest in harbor seals. In many ways, his anger illustrates the level to which emotions have risen on both sides of a debate over how much protection the skittish whiskered pinnipeds really need.
Though by no means a rare sight in the waters off California, the harbor seal is a timid, retiring creature, acutely affected by the activities of people. Some people insist the animal needs diligent protection from human interference to survive the rush of civilization. Others, particularly commercial fishermen, argue that the animal is in fact a nuisance, a competitor that must be controlled.
Ever since the passage of the Marine Mammal Protection Act in 1972, populations of harbor seals have increased along the West Coast. Inevitably, so have their confrontations with people. The animals pup, breed and fish at or near the mainland, making them more susceptible to pollution and human disturbance than other seals and sea lions that spend most of their lives on offshore islands.
Harbor seals eat many of the salmon and white sea bass that coastal fishermen also seek, so in the past, fishermen and bounty hunters shot many of the unwelcome competitors. Today, even though federal law prohibits outright killing of the animals, the California Department of Fish and Game estimates that as many as 2,000 seals accidentally die in fishermen's nets off the California coast every year.
Harbor seals inhabit waters on North America's West Coast from the Bering Sea to Baja California, and on the Atlantic Coast from Newfoundland south to the Carolinas. They also live off the coasts of Europe and northern Asia. The creatures are lighter and more compact than their Pacific pinniped cousins, the California sea lion and the elephant seal, and their coats are more spotted and colorful. On land they plod along like inch worms, but in the sea they move like torpedoes.
For years, biologists have tried getting a closer look at the harbor seal to study its life cycle, population levels and the numbers its range can support, but the animal's secretive nature makes the job a tough one. While California sea lions and elephant seals leave the water for a month or more for elaborate courtship and pupping, harbor seals mate in murky coastal waters and come out on land mostly just to rest and bear young.
"It's very difficult to observe the animal behaviorally," says Deane Renouf, harbor seal expert and associate professor of biopsychology at Memorial University in Newfoundland. "As soon as it sees a person on the horizon, it disappears into the ocean. And just about everything it does that's of interest happens in the water."
The creatures' mottled dark coloration doesn't make observing them any easier, though it can provide clues about a particular animal's background. Individual harbor seals have complex color and spot patterns that appear to vary geographically. Seals in the San Francisco Bay, for instance, tend to have reddish coats, while others sport more of an earth tone.
Brent Stewart and Pamela Yochem of the Hubbs Marine Research Center in Southern California have been working to develop a system for classifying the creatures' color patterns. Eventually, researchers hope they will be able to use the seals' natural markings to distinguish among specific populations and identify individuals without having to tag them. As it is, the elusive animals are difficult to tag in sufficient numbers and hard to approach for resighting.
Harbor seals normally even eat in private, preferring to dine below the surface and away from prying scientists. Enormous eyes allow the animals to see better underwater than humans can see on land. In the dark depths seals may even use their whiskers as motion detectors to home in on the tail vibrations of fish.
Scientists speculate that harbor seals developed their shy disposition in response to onshore attacks long ago by bears, wolves and mountain lions, predators unknown to their offshore cousins. Nature did not, however, prepare them for the onslaught of bounty hunters who drastically 'depleted the seals' population in the first half of this century. Biologists estimate that from 1943 to 1960, about 1,000 harbor seals were killed annually off the coast of Washington. Between 1938 and 1942, Oregon bounty hunters killed more than 500 each year in the Columbia River alone. Though similar figures are not available for California, scientists believe populations there also plunged.
The Marine Mammal Protection Act allows commercial fishermen to chase away and, if necessary, kill harbor seals that interfere with their fishing operations. But the question remains: how to define "necessary"? Two years ago, the Marine Mammal Commission revised its rules to require that observers ride along on some boats to make sure fishermen kill seals only as a last resort. And these tighter controls have only added to the fishermen's frustrations.
Seals in the Columbia River are usually so distracted by spawning smelt, a noncommercial species, that they leave more salmon for the fishermen. Last year, though, the smelt run was late. "Our guys really got clobbered," says Kent Martin, chairman of the Columbia River Fishermen's Protective Union. Martin resents outsiders with what he calls "Disney notions of nature" passing laws that affect his occupation. "I see no reason why harbor seals can't be managed any less than deer or elk," he says, echoing a sentiment shared off the record by some scientists.
On a high bluff in a remote corner of Point Reyes National Seashore in northern California, Sarah Allen, a research biologist with the Point Reyes Bird Observatory, gazes through a spotting scope at distant dots in the estuary below. The dots are actually harbor seals, more than 500 of them, sprawled out on sand bars.
There are about 400,000 harbor seals worldwide, and Point Reyes is home to about 3,000 of them—fully 15 percent of California's entire breeding population. Biologists estimate that the state's current total is half what it was before the onset of bounty hunting. Even so, the animals' numbers at Point Reyes have perhaps doubled in the 18 years since the Marine Mammal Protection Act became law.
At Point Reyes, harbor seals hunt by night and haul out (come ashore) for an average of seven to nine hours during the day. With less blubber and fur than other pinnipeds, the animals need to haul out daily to conserve energy. And while their cousins joust, court and mate on the beach, harbor seals use their shore leave only for resting and raising pups.
Allen points to a pair of seals, a male and female, torpedoing through the water in tandem, then pausing to nuzzle. "This is precopulatory display," she tells a visitor. "You may be one of the rare ones ever to witness a harbor seal mating." Just then, the pair dives deep into the murky water and disappears. "It's like that," says Allen, shaking her head. "We see only little vignettes—seldom the whole scenario." By piecing these little vignettes together, however, Allen and other biologists are gradually getting a much clearer picture of harbor seal behavior.
Male harbor seals at Point Reyes grow to an average length of 5 feet and weight of 188 pounds, females to 4.5 feet and 136 pounds. The creatures live an average of 20 to 30 years. A few years ago, Allen and a crew of biologists attached transmitters to Point Reyes seals and found that they migrated as far away as Monterey Bay to the south and the Klamath River to the north—a total range of 418 miles.
Females at Point Reyes give birth to their pups from late March through April. They nurse their young for about 30 days, during which time the pups' weight doubles. Shortly afterward, the females abandon the pups and mate. Human activity within 100 yards from the animals can send resting harbor seals splashing into the water, so during the breeding season the flurry of wind surfers, canoeists and jet skiers at Point Reyes may be taking a toll on the seal population. In a study covering one 2-year period, Allen found that the harbor seals there were disturbed 71 percent of all the days they were monitored.
The problem is most critical for newborn pups. Though adult harbor seals are generally silent, a pup makes loud cooing sounds vital to the formation of the mother-pup bond. The mother uses both sound and smell to locate her pups in rough waters or packed herds. Bonding is usually established in the first few days of a young seal's life, but if the animals are disturbed before the bond is solid, says Allen, "it can be fatal to the pup." In her studies in Newfoundland, Deane Renouf found that as many as 10 percent of unweaned pups separated from their mothers starve to death each year.
At Point Reyes, the harbor seal's only natural predator is the great white shark. Every year, Sarah Allen sees fresh shark wounds on the bodies of as many as 5 percent of her study seals—"and those are only the ones that got away," says the biologist. Even so, the creatures may be affected less by the sharks in California's waters than by poisons in the water.
Seal populations in San Francisco Bay have remained static over the past 15 years despite the doubling at Point Reyes 50 miles to the north. Recently, researcher Dianne Kopec of the Romberg-Tiburon Center for Environmental Studies began taking blood samples from captured harbor seals as part of a two-year study of seals in the bay. Because the seal is an apex predator, at the top of its food chain, it is subject to what scientists call a bioaccumulation of pollutants. Pollutants are attracted to fatty molecules in fish and accumulate in the animals to levels higher than those found in the water. Says Kopec, "This increased pollutant concentration is passed up the food chain every time a predator eats a prey."
Many biologists suspect that pollution made European harbor seals more susceptible to a virus related to canine distemper that, in 1988, wreaked havoc with the seal population in the North Sea. "There were 17,000 animals there that died from that disease," says Kopec. "That's an enormous number of marine mammals." But as it turns out, seal carcasses that washed up in the San Francisco Bay 14 years before the North Sea epidemic had equally high levels of PCBs and the chemical DDE. Could San Francisco's seals be poised at the edge of a similar disaster?
Should the seal population plunge, some of those who compete with the animals for fish probably wouldn't call it a disaster. Gill net fishermen in the Channel Islands off Southern California report that the creatures literally race them to their nets in the morning. "Occasionally, the seals get caught and drown," says California Gillnetter's Association Vice President Tony West. "Then environmentalists get all upset."
The revised federal law calls for all commercial fishermen to register with the Marine Mammal Commission and for observers to go along on boats that fish in the same waters as seals. And though harassment of harbor seals can bring stiff fines, the animals' bodies still wash up on shore now and again with bullet holes in them.
And on those shores, harbor seals continue to butt heads with people as fiercely as they do in the water. Not long ago, more than 100 seals abandoned a favorite haul-out site at San Francisco's Strawberry Spit when joggers and dogs began visiting the area regularly. To many California biologists, the exodus from the spit is not an isolated event but rather a disturbing vision of things to come. "With so many people moving to the coast," says Dianne Kopec, "one wonders if both species, man and harbor seal, can coexist."
California writer Michael Tennesen visited harbor seal rookeries along the state's coast in preparation for this article.