OGUNQUIT – Whale watching was even more hit or miss than normal this summer off the New England coast. Boat operators and marine experts say large migratory whales were unusually scarce from Cape Cod to Bar Harbor.

“Across the board, there’s been a real paucity of whales in the typical places,” said Laura Ludwig, a whale specialist with the state Department of Marine Resources. “They’ve had days without seeing whales, which is real rare.”

Farther south, there have been similar reports.

“I know the whale watching boats were desperate around Massachusetts,” said Scott Kraus, a whale researcher from the New England Aquarium in Boston. “They didn’t have a very good July and August.”

Some boat operators blame herring fishing boats that have become more numerous off the Maine coast.

“On the big scale, it could be warming water temperatures, global warming, the alignment of Mars and Jupiter,” said Toby Stephenson, a naturalist at the Bar Harbor Whale Watch Co. “But on a small scale, when trawlers go out to fish, the next day we know we’re not going to see a lot of whales.”

Ludwig shares the same suspicion.

“I have no question in my mind that the efficiency of the … trawlers can really impact a herring population,” she said. “And the only reason these whales are where they are is the food source. … When a fishing vessel breaks up a mass of a school, it’s inefficient for the whales to stay and feed on a broken school, so they go elsewhere.”

Herring is a favorite food for humpbacks and finbacks.

Mary Beth Tooley of the East Coast Pelagic Association, a herring industry group, conceded the prevalence of such belief but questioned its foundation.

“They feel that way, but there’s nothing to substantiate that,” she said.

Meanwhile, one report put an unusually large number of humpbacks feeding on herring around Brier Island, which is located near Digby in southwest Nova Scotia.

Shelley Barnaby, a naturalist at Brier Island Whale and Seabird Cruises, has identified many of the humpbacks from markings and fin shapes as individuals that typically spend the summer feeding on Jeffreys Ledge.

Humpbacks have been feeding within three miles of the island.

“There’s more, and they’re closer,” Barnaby said.

Scott Kraus, who studies the northern right whale, which has a different diet, described “a real strange summer.”

“Hardly any whales most of August. Then they arrived about a week ago, and there are a lot of them. Everything all of the sudden seems normal,” he said.

Kraus suggested factors affecting whale presence could include water temperature and toxic red tides.

“I think it’s temporary. I don’t think it’s related to any fishing. My guess is that these kind of things come and go,” he said.

“People are just starting to notice these things more. You’ve got to remember that whale watching just started in the late ’70s, so our history with whale watching is not very long.”