“They’re not spawning, they’re fleeing,” said Denny Morrow, Executive Director of the Nova Scotia Fish Packers Association, describing fish trying to avoid being eaten by grey seals that attack tight spawning schools.
We all look for seals when on the water. Their sleek heads and big brown eyes emerging above the waves or the entire animal sunbathing on an outcrop of rock or island we find as appealing as that graceful deer daintily picking its way through our back yards — unless that deer runs into our car and totals it. An overabundance of deer loses its appeal, and for the most part we don’t argue about a reasonable deer hunt. Why, then, does the thought of a harvest to curb a massive overabundance of the grey seal (Halichoerus grypus) bring out some people’s protective instincts?
We’re not talking about the common harbor seal (Phoca vitulina) or the Arctic harp seal (Phoca groenlandica), which only migrates to Canada for three or four months each year to breed and “pup,” the term for bearing young. The grey seal, a Canadian native weighing from 600 to 1,000 lbs., has traditionally bred and pupped on Sable Island, on the Scotian Shelf east of Halifax, Nova Scotia.
Atlantic Canada has been inundated with a mushrooming population of grey seals, a herd that has been growing at 12 to 14 percent each year, according to Canadian Department of Fisheries and Oceans [DFO] statistics. This population has escalated from about 30,000 thirty years ago to some 300,000 now. (Some estimate the population as high as 400,000.) There are now too many grey seals for Sable Island, so they are now establishing new breeding colonies at the mouth of the Bay of Fundy near Georges Bank and Brown Bank. They have also established breeding colonies on two islands in Penobscot Bay and on Muskeget Island, between Nantucket and New Bedford.
Only Iceland and Norway protect fish and lobster by culling the grey seal herd. Morrow, who has called for a 50 percent reduction of the Sable Island, Nova Scotia, herd over the next five years, said, “We have the right to hunt them, but the regulations make it so difficult, the herd is basically left alone. Sable Island is a protected wilderness island.”
James Gilbert, Professor of Wildlife Ecology at University of Maine, has been doing aerial surveys of the Penobscot Bay herds since 1989. He said, “There are approximately 40 grey seals on Green Island and 200 on Seal Island. Sable Island produces in excess of 50,000 pups a year.”
“This story needs to get out,” Morrow said. “I think the New England fishermen, as this grey seal herd spreads down the coast, are going to experience the kind of impact we’ve felt, what we’re going through up here, so they’d better get ready.”
The spread of grey seals is not good news for groundfish or for Canadian and New England groundfishermen because the grey seal is a groundfish predator and the main carrier of a worm or parasite called sealworm (Pseudoterranova decipiens), formerly known as codworm.
Look up “sealworm” or its Latin equivalent via Google and you will find that the parasite reaches sexual maturity in the warm-blooded grey seal’s intestines or stomach. The seal then excretes sealworm larvae and eggs, which fall to the ocean bottom where small, bottom-dwelling animals, called benthic organisms, eat them. In many cases fish eat these infected organisms, which means the eggs or larvae hatch and start to grow in the fish, which in turn become infected.
Morrow of the Nova Scotia Fish Packers Association said that Loyola Hearn, Canada’s Minister of Fisheries, while visiting fish plants in Southwest Nova Scotia in early April, happened to see a codfish that had 192 worms picked out of its flesh. Although Canadians used to see these parasites mainly in cod and flatfish, such as flounder, they are now also finding them in halibut and haddock. And not just in Canada. These worms are showing up in fish in the US, too.
Some years ago Susan MacNair, of Penobscot, Maine, cooked some haddock she had bought at the supermarket and, just as she was about to take a mouthful, noticed a worm in the flesh. It turned her off fish for some time.
Occasionally, humans have been infected with sealworm after eating raw or barely cooked fish.
The revolting aspect of finding worms in fish, raw or cooked, aside, in addition to the damage done by infecting fish, these thousand-pound animals attack fish in gillnets and other nets, killing or damaging the fish and tearing up the expensive nets. Both Nova Scotia and Massachusetts fishermen have seen evidence of grey seal predation. John Levy, an east coast Nova Scotia lobsterman and president of the Fishermen and Scientists Research Society who has been involved with studies on juvenile lobsters, said that marine biologists call the damage “belly bites” because the seals go for the gonads and liver, which have the highest amount of protein. According to Cape Cod groundfisherman Michael Russo, of Orleans, MA, the grey seals strip the fish off longlines. “They take the bellies of cod and haddock. They target the livers. They’re pretty surgical. We’ve watched them.” He used as evidence a grey seal that had gotten hooked on one of his longlines and drowned. Russo stated that fishermen have seen grey seals as far south as New Jersey.
Virginia Boudreau, Manager of the Guysborough County Inshore Fishermen’s Association (GCIFA), whose fishermen fish the eastern tip of mainland Nova Scotia and Chedabucto Bay, said her fishermen had to give up their herring and mackerel fisheries because grey seals tore up the nets. “The groundfishery is gone,” she said. “Small cod and small haddock: in our area they don’t reach maturity. [They’re] either eaten by [grey] seals or die from sealworm.”
“We have less and less groundfish to process every day,” Morrow reported. “The gradual loss of our groundfish industry is resulting in more pressure on the lobster fishery as fishermen and [fish processing] plants have no other species to turn to.”
No one interviewed for this story wants to decimate the grey seal population; several spoke of keeping it “within reason.”
Everyone involved — Morrow, Nova Scotia fish plant owner Adlai Cunningham, of Seastar Seafood, Boudreau, and Canadian and U.S. groundfishermen — referred to sealworm-infected fish as “slinks.” They’re skinny, long, and lanky because the worms are feeding on their flesh and converting the fat content to fish that are thin and not healthy.
Kristen Ampela agrees. In her doctoral research at the City University of New York Graduate Center on the diet and feeding habits of the grey seal off Cape Cod, she has seen evidence of grey seals raiding traps and nets. Levy, who has suffered the same problems as Spinney, said the seals also eat soft shelled, recently molted lobster and that he and others have witnessed, as they throw back undersized lobster, grey seals following the boat, “dive down and grab the small lobster before they reach bottom.” Frustrated, he muttered, “So much for conservation.”
There had been a bounty on seals in the U.S. until the Marine Mammal Protection Act of 1972. Russo said when grey seals first showed up at Cape Cod, there were only six. He estimated the Muskeget herd today at 10,000. “You have to take their predations into fish stock into account when writing regulations,” he said and added, “I would like to see more ecology-based management. Nobody’s raising the flag except fishermen.”
Because of its size and weight, the grey seal has few predators. Cape Cod gillnetter Robert St. Pierre, of West Yarmouth, a thirty-year veteran, counts as the only ones the great white shark (Carcharodon carcharias), mako sharks (Isurus oxyrinchus) the shortfin and (Isurus naucus) the longfin version, and the porbeagle shark (Lamna nasus). He said sharks drive the seals inshore, noting that there are a half-dozen eyewitness accounts of encounters between grey seals and sharks. He added, “Porpoises also drive seals inshore.” He stated that beginning in May and by mid-June no grey seals go beyond eight or ten miles and come even closer “By July through December,” he said, “they are feeding up against the beach.”
St. Pierre charges the grey seals won’t allow fish to aggregate to spawn. The result: “The spawning success rate has gone down considerably.” He said the seals feed in a pack and that it’s not unusual to see 16 to 20 grey seals cruising together. “It’s hard for me to understand a direct effect on haddock and pollock, but I have witnessed the demise of the codfish,” he said. “We used to have a wonderful winter and spring fishery here on the Cape. You know, contrary to popular belief, there’s still a lot of codfish in the ocean; they don’t come here anymore. You can’t blame ’em.” He attributes this “absolutely” to grey seal predation. He called the grey seals “very, very smart” and said they have connected themselves with cod spawning cycles.
Nantucket shoals and the water off Cape Cod have been nurseries for juvenile codfish. Grey seals rest on nearby Monomoy Island. But juvenile codfish aren’t as smart as the seals that feed on them. “Any calm day,” St. Pierre said, “you can see a seal with a 20-inch cod in his mouth. When he finishes it, he turns around and goes back down for another. They do this 24 hours a day six months a year.”