“The only good seal is a dead seal,” quips a fisherman when the subject of the recent seal population explosion comes up at the West Point Store in Phippsburg. The observation pretty well sums up how most fishermen feel about these mammals that tourists and recreational boaters find so entertaining.
Seals eat just about any fish, plunder bait in lobster traps and create havoc in fishing weirs and aquaculture pens. Many fishermen regret that the 1972 Marine Mammal Protection Act (MMPA) put an end to killing them.
In the old days, says one West Point fisherman, men who fished in pounds (a type of weir) used to sit in their boats beside the pound and shoot seals that tried to get in. Once in the pound, he explained, the seals would not only munch on fish for dinner; they would disrupt the fish from their habitual circling around the pound, which kept them from noticing the way out. While the fish were swimming frantically to escape the seal, one would discover the entrance, and the others would follow it out.
In the early 1970s, the seal population was reduced to an estimated 5,000 animals in Maine waters; hence, their inclusion in the MMPA. But now, according to a study conducted by James Gilbert of the Department of Wildlife Ecology at University of Maine at Orono and Gordon Waring of the Northeast Fisheries Science Center, the population has exploded, with nearly four times as many seals actually counted in 2001 (38,011) as in 1981 (10,540). Gilbert and his colleagues estimate there was a total of approximately 100,000 seals, the majority harbor seals, in New England waters during May and June of 2001. To obtain this figure, they used aerial surveys to count all visible seals and radio tags to track the movement of other seals under water, which provided a way of estimating the number not visible in the photos.
Sebastian Belle, director of Maine Aquaculture Association (MAA), says seals cause problems at farm sites when they approach pens and frighten the fish. On rare occasions, they have managed to tear a hole in the net and allow fish to escape. Belle says when fish are stressed by seals, a series of physiological effects occurs which affects fish health. “Fish farmers’ main goal in life is to minimize stress on fish,” he says, “because a happy fish stays healthier and converts feed well and grows well, and then farmers make more money.”
Ten years ago, salmon farmers estimated they lost about one and one-half to two million dollars a year due to seal interference.
More recent figures aren’t available, but during the past 10 years, farms have spent considerable money to update their predator deterrent systems, which focus on modifying seal behavior. These include stronger nets on salmon pens, new acoustic devices and increasing the presence of workers at the sites. Farms are mandated by their recently formed Bay Management Groups to develop an Integrated Predator Deterrent Program which is modeled on integrated pest management programs in agriculture.
The MAA has applied for funding to study the latest net technology available for farmers. “There are some new net materials on the market which were developed principally for commercial fishing,” says Belle. “They are much stronger, but also much more expensive.”
The association also has asked for funds to purchase and test a new sound device which senses the presence of a seal by sensing sound shifts under the water. “The device only triggers when a seal approaches the pens,” says Belle, explaining that this addresses one of the difficulties with the acoustic devices currently in use – they generate random sound and there is no linkage between the behavior of the seal and the emergence of the sound.
Gilbert, who has studied the Northeast’s harbor and gray seal population for more than 20 years, says although a plentitude of anecdotal evidence exists about the effect of increased numbers of seals on the groundfish population, no solid figures can document the connection. However, he says, it is well known that seals feed on Atlantic salmon, herring, cod, hake, winter flounder, alewives, squid and other species. In one study of the stomach contents of 75 harbor seals taken in the offshore Gulf of Maine, hake was the most common food.
Seals also carry cod worm and transmit it to groundfish, which although it does not kill the fish, affects its marketability.
Gilbert has applied for funds to begin a study that will look into the effect of seals on wild salmon entering Maine rivers. Belle hopes this will shed new light on reasons for the downturn in the wild salmon population. “I drive back and forth Down East a lot, and I frequently see the seals, mergansers and cormorants (also no friends of fishermen and fish farmers) when I drive across bridges at the mouths of rivers,” he says.
The fishermen from West Point have few doubts seals must be affecting river fish populations, noting that at Fort Popham, where seals hang out at the mouth of the Kennebec River, “It’s like the fish are running a gauntlet.”
On the West Coast, says Gilbert, the National Marine Fisheries Service has recognized that seals are a danger to wild salmon and has recommended that taking Pacific harbor seals be permitted again on a limited basis “to reduce impacts of seal predation on endangered salmonid stocks.”
A solution for controlling the seal population is not clear. Gilbert says opening the MMPA to modify restraints on killing seals could trigger new problems for the fishing and aquaculture industries. In addition to seals, the law protects whales, polar bears, sea otters and manatees. “If it is opened for modification, then people will start to look at the entire law,” he says. “There’s the potential that some parts may be made even more strict than they are now.”