Photo by Marcy Lucas

The Bold and the Beautiful
UMaine wildlife ecologist keeping count of the state's growing seal populations

Sidebar Steve Renner On a three-and-a-half-acre island off the coast of Maine, Steve Renner spends weeks at a time recording the behavior of the inhabitants. He wants to know how the island's two sets of neighbors — longtime resident harbor seals and the relative newcomers, gray seals — get along.

Sidebar Marcy Lucas In the marine world, Marcy Lucas is the equivalent of a law enforcement profiler. She is studying the modus operandi of the most wily, slippery predators known to Maine's Atlantic salmon industry — harbor seals.

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Look beyond the endearing coal-black eyes, whiskered face and soft short fur and you'll find a carnivorous wild animal with sharp claws and teeth. Look into the depths of the complex marine ecosystem and you'll find culpability is not black and white when it comes to seals.

Wildlife ecologist Jim Gilbert says the realities about seals lie somewhere between two opposing views of the marine mammals. And he should know. He's studied seal populations for almost 30 years.

For many landlubbers, seals are imbued with marine mystique. Adult seals in the Maine wild draw sightseers while stranded pups on beaches spark all-out rescue efforts. The most famous of Maine's harbor seals was Andrι, whose life is immortalized in a children's book, film and a marble statue. However, for those who make their living from the sea, seals can be the bane of their existence. Since 1972, seals have been under the Marine Mammal Protection Act, but little protects fishermen and fish farmers from the damage seals do to equipment, such as fishing nets and aquaculture pens.

Lobstermen claim seals steal bait from traps and eat shedding crustaceans. Seals are blamed for hurting Maine's Atlantic salmon industry by preying on farm-raised and wild stocks. The recent dramatic decline of cod has been linked to the increasing seal populations in Maine. But it's not that simple, says Gilbert.

"One could also argue that cod and seals are competitors for a common food source," he says. "When cod decline, seals increase. The marine ecosystem is more complex than the classic food chain."

Gilbert's research focuses on population studies of large mammals. Throughout his career, he has traveled to some of the most remote corners of Alaska, Russia and the Antarctic to conduct population surveys that inform wildlife conservation and management methods and policies. He also has worked to develop effective methods for censusing marine mammals. He has studied brown bear and moose, bottlenose dolphin and harbor porpoise, polar bear, and gray and white whales. Pacific walrus are Gilbert's long-time preoccupation. Seals have been the mainstay of his research.

"I had never seen a seal until I went to Antarctica," says Gilbert, who, as a gradate student, eventually spent two seasons on the continent studying four species of seals. "Prior to our trip, only a dozen Ross seals had ever been sighted. On our two-week trip, we saw 50."

In his wildlife population studies, Gilbert has witnessed a number of awe-inspiring sights. On a 1989 survey undertaken in cooperation with Russian scientists, he saw a quarter of the world's gray whale population. Once on a walrus study in the Chukchi Sea in the Arctic Ocean, an opening in the ice revealed the presence of 5,000 white whales.

Such unexpected sights in nature make even the most veteran scientist involved in wildlife population studies stop and take in the beauty. That curiosity and fascination also are behind Gilbert's decades of research. No matter how many thousands of harbor, ringed or gray seals he's counted, there are still more data to collect and questions to be answered. Especially in Maine.

"Off the coast of Maine, the big questions have to do with the increasingly complex seal populations," Gilbert says. "We don't just have harbor seals born in Maine any more. Colonies of gray seals have been established. In the winter, we have harp and hooded seals in the Gulf of Maine in numbers that never used to be there."

Harbor seals have been part of Maine's marine ecosystem for centuries. Early Native American middens in the state include the bones of harbor seals. Gray seal bones also were found in middens. However, there has not been any indication they were pupping in Maine prior to 1994.

Today, it is estimated that 250 gray seal pups are born off the coast annually. "It may be that some from Canada are moving down," Gilbert says. "On Sable Island (Nova Scotia) fewer than 200 gray seal pups were born in 1962; the breeding site has now broken 20,000 pups each year."

Gilbert has been involved in tagging seals off the Maine coast since 1981. He also has done more than a dozen aerial surveys of seals since that time.

It takes almost six days to do an aerial survey of the Maine coast. That involves hours of continuous flying in a small aircraft, usually repeatedly circling areas for the best photos of seals at altitudes as low as 600 feet.

Along the Maine coast there are more than 3,000 islands and ledges of varying size, including those only exposed at low tide. Such ledges are haul-out sites where seals sleep, pup and molt, and researchers get the best census opportunities.

The two annual peaks in harbor seal haul-out numbers occur during the pupping and molting seasons in May – early June and in late July – early August, respectively.

In 1981, Gilbert's first seal survey in Maine found a harbor seal population of 10,450; by 1997, there were 30,990. These were actual counts; some seals are always in the water and not counted.

As the population increases, researchers predict that harbor seal pupping areas will expand in the near future, making the sea mammals residents rather than visitors on the coasts of states south of the Maine – New Hampshire border.

More seals mean more damage to fishermen's harvests and aquaculture pens. And while harbor seals are the primary raiders of fish farms, gray seals may join the vandalism as their colonies become more established.

"In the Atlantic salmon issue, many people blame the growing number of seals for problems with predation, including damage to equipment and release of farm-raised stocks," Gilbert says. "But when you look at seals' food habits, they have little to do with salmon. However, two or three seals at the mouth of the river catching wild salmon are like a fox in a henhouse. That's not a population problem but an animal damage problem caused by a handful of individuals."

Gilbert's newest research focuses on the predation by seals at the mouths of Maine's wild Atlantic salmon runs. One of his graduate students, Marcy Lucas, is working with commercial aquaculture facilities in the state, where the majority of the escapes of farm-raised fish are attributed to harbor seal predation. Graduate student Steve Renner is studying the interaction between harbor and gray seals.

In spring 2001, the three were involved in a seal tagging and population survey project, working in cooperation with the National Marine Fisheries Service in Woods Hole, Mass., and Maine's Department of Marine Resources. Twelve seals were radio tagged in Cape Cod, and another 17 were tagged in Rockland, Maine. The seals each received two radio tags, one glued to the lower back, another on a rear flipper.

The radio tags last about six months before they are lost in late-summer molting.

The tagging operation is designed to help scientists determine the fraction of the population in the water when aerial surveys occur. While the latest data are still being compiled, it appears that any aerial counts of seals should be multiplied one-and-a-half or two times, Gilbert says.

Increases in population size, including a rising number of pups, are indicators of a lot of good food for these animals. In this year's survey, Gilbert saw more seals on ledges along the Maine coast than ever before.

"It could be because they have more protection, more food or fewer competitors, or that there's less pesticide contamination in the ecosystem," he notes.

One question to be answered in Maine concerns the distinction of seal colonies within a species. Determining the distinct groups of seals living along the Maine coast could shed new light on such dynamics as survival and reproductive rates — and their future relationship with people in the state.

by Margaret Nagle
February-March, 2002

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