HALIFAX — Federal scientists now say there may have been a "confluence of events" that led to hundreds of thousands of dead herring washing ashore off southwestern Nova Scotia.
Alain Vezina, regional director of science for the Department of Fisheries and Oceans (DFO), said Thursday there were unusually large schools of herring in St. Marys Bay in late November when they began turning up dead by the thousands on a 100 kilometre swath of shore.
Vezina told a Nova Scotia legislature committee those numbers were unusual, but such "totally unpredictable" population spikes do happen.
At the same time, the area was struck by volatile weather, including high winds and temperature dips, he said, and predators may also have had an influence.
"These factors probably interacted in some way to generate these events," said Vezina. "To go back and understand very precisely exactly what happened would be extremely difficult because we don't have the data at the scale fine enough to say, 'OK that's the smoking gun here.'"
He said the kill was ultimately a "small and localized event," and remains a mystery. Later in December scores of starfish, clams and lobster also turned up dead with the fish.
"We certainly know what it isn't," said Vezina. "It's not human caused and it's not toxins that are generated in the environment that would have moved through the food chain into the herring."
While fish kills in fresh water aren't uncommon, the last kills of comparable size involving herring in the Bay of Fundy occurred in 1976 and 1979.
Vezina told reporters that DFO estimates hundreds of thousands of herring died and were washed ashore in December, while untold numbers of fish were also lost to predators such as seabirds.
But he said the overall number was a small fraction in terms of the overall percentage of allowable catch given to fishermen.
"Our worst estimates we're talking maybe one million, two million fish. It's still very small compared to the number of fish that are captured in the fishery annually."
Frank Dunn, deputy minister of Nova Scotia's Department of Fisheries and Aquaculture, said the province's herring fishery is worth about $16 million annually, with spinoff work boosting that figure to $24 million. He said eight plants employing several hundred people process herring.
Dunn said despite appearances, the fish kill has not had a significant impact on the industry or its reputation.
"Although the impact and the size was optically large, the advice that I have been given ... is that it will have no impact on that fishery."
Dunn said while he was told one processor received a call from a U.S. buyer as a result of publicity around the fish kills, his department has had none.
DFO officials said they are continuing to monitor the area, but believe the kill event is concluding.
Keith Doucette, The Canadian Press