PORTLAND – There are more seals off the Maine coast now than there have been in more than a century.

At least that’s what a seal survey now under way is likely to reveal.

You won’t get any argument from Bob Fish, who operates Cap’n Fish’s Whale Watch and Nature Cruises in Boothbay Harbor. He sees more seals these days than at any time in his 40-plus years in the cruise business.

“There are a lot more seals out there now – a ton of seals,” he said. “They’re out there because nobody’s bothering them and there’s plenty of food.”

When the survey results are compiled in September, the harbor seal count is expected to surpass 31,000. That would compare to 5,000 just 25 years ago. And a century ago, seals were nearly eradicated from parts of the coast.

The abundance of seals is a sign of a plentiful food supply, a relatively clean environment and conservation laws that apparently work.

It is good news for seal lovers and those who directly benefit from a healthy seal population, such as seal watch cruise companies. But it’s not so good for salmon farmers and fishermen, who have long cursed seals as nuisances.

Until 1905, the state paid a $1 bounty on harbor seals to reduce their populations to help fish stocks, according to Steve Katona, a marine biologist and president of College of the Atlantic in Bar Harbor. Bounty hunters brought in seal noses to prove their kills.

By the early 1900s, the seal population was nearly exterminated along some parts of the coast – with no noticeable effect on fish catches.

Maine lifted the bounty in 1905, but Massachusetts retained its seal bounty until 1968, and Canada had a bounty until 1976.

Seal populations rebounded, but there were still only 5,000 or so of them off Maine in the early 1970s. Fishermen sometimes still killed them on the sly for messing with their nets and traps.

Thanks to the Marine Mammal Protection Act of 1972, which made it illegal to kill seals, the numbers began growing in earnest. A 1981 survey identified about 10,000 seals and a survey five years later counted 12,000.

The greatest population surge, though, has come in the past decade. In 1997, the year of the last seal census, researchers counted about 31,000.

James Gilbert, a professor of wildlife ecology at the University of Maine who is heading this year’s survey, is hesitant to predict what the outcome will be. But he says the numbers will probably be as high or higher than the last census.

“At least to the back of the turn of the [last] century, we probably have more now than ever before,” he said.

To count the seals, surveyors flew in two planes in the spring and shot 236 rolls of film – a total of 8,496 pictures – of hundreds of islands and ledges from New Hampshire to Canada. They are using a slide projector to physically count the seals in each frame.

Researchers also attached radios to the backs of 30 seals in Chatham, Mass., and Rockland to track their whereabouts. That will allow scientists to estimate how many seals are in the water and not able to be counted.

Studies along the Pacific coast estimate that there are 150 to 185 seals for every 100 that are counted, Gilbert said. If that is the case on the Atlantic coast as well, that means there could be more than 50,000 seals in Maine.

For all their cuteness, though, seals aren’t beloved by everybody.

Lobstermen complain they break into traps and steal bait bags and the occasional lobster. Fish farmers say they swim under fish pens and stress fish or tear open nets and release the pricey salmon.

The impact on salmon pens has been lessened because of new materials and new methods to keep seals from ripping open the pens, said Sebastian Belle, executive director of the Maine Aquaculture Association.

To keep seals away from nets, salmon farmers have been known to use acoustic “seal scarers,” killer whale decoys and even scarecrows on fish pen platforms to scare them away.

Still, the aquaculture industry is concerned with the growing numbers of seals.

“Our interest in the seal issue is in a healthy vibrant ecosystem,” he said.

And while the seal numbers in Maine are healthy, they are piddling compared to Canada, where there are more than 5 million seals. Canada each year has a commercial seal hunt for harp seals; this year’s quota is 275,000 animals. There are markets for seal fur, leather and meat.

Not only are there more seals in Maine, there are also more people interested in seals, according to cruise boat operators.

Tom Ring, owner of Atlantic Seal Cruises in Freeport, said there seems to be a growing public interest not only in seals, but also in ospreys, porpoises, whales and the like.

“People just seem to be more interested in nature,” he said.