Fishermen in parts of Atlantic Canada are worried that warming waters and a changing marine environment are threatening a fishery that supports hundreds of jobs and provides food for other species.
Fishermen in P.E.I., New Brunswick and Nova Scotia are all reporting low catches of herring, if they're able to find them at all.
Chuck White, who's been fishing the sleek, silver fish for 25 years, said he came back into port last week with empty nets, finding few herring on the Island's south shore.
“We went out and there was nothing around,” he said from Murray River. “The last few years, the warmer water temperatures seem to be keeping them out.”
Mr. White says water temperatures in the area where he fishes have been several degrees warmer than previous years.
Boats that fish the Bay of Fundy are also having trouble hauling in normally bountiful catches of herring, which are a source of roe for the Japanese market, bait and canned fish.
Fishermen say they suspect the fish are there, but are staying closer to the ocean bottom where the water is cooler.
Dick Stewart of Atlantic Herring Co-op Ltd., said water temperatures are up to six degrees warmer around German Bank, a rich fishing area at the mouth of the bay.
He said fishermen estimate there are 95,000 tonnes of herring on the bank, but are hard to get at because they're so deep.
Mr. Stewart said he's never seen temperatures this warm in the bay, which is also seeing a dramatic drop in the amount of phytoplankton which sustains several species.
“My concern is that this is the start of a new trend that's happening because of the changes in the ocean and the climate,” said Mr. Stewart, who's been involved in the fishery for 50 years.
“That's why I think it's critical to study what effects this will have on every fish stock probably, let alone herring.”
Scientists are trying to determine what's happening to the stocks, which fishermen say are also much smaller.
The Department of Fisheries has sent a research vessel to the German Bank, off the province's southwestern coast, to figure out how many fish are there.
Harold Theriault, a Liberal member of the legislature on Nova Scotia's southwest coast, said the lack of fish is taking a toll on the hundreds of people who can't get work at herring processing plants.
“There's 500 or 600 families down on these shores who are out of work or don't have enough hours for employment insurance,” he said from Digby.
“It's going to be tough going this winter.”
Mr. Theriault, who used to fish herring, said the multimillion-dollar fishery needs to be scaled back or even shut down in the spawning grounds to let it rebound, though it remains unclear whether the stock is in bad shape.
Jeff Hutchings, a marine biologist at Dalhousie University in Halifax, said the species, which is a food source for whales, porpoises and groundfish, tends to bounce back fairly quickly even when it's been depleted.
But water temperatures can be critical to where the fish position themselves in the water, possibly signalling a more lasting change in the fishery.
“Their position in the water column is most definitely influenced by water temperatures and its spatial distribution is also influenced by water temperature,” he said.