Herring washing ashore in St. Marys Bay leaves scientists puzzled

Scores of Atlantic herring are washing up on the shores around St. Marys Bay, N.S., but the reason isn't clear.

Within the last week, the herring have appeared on a 20-kilometre stretch of shoreline running between Marshalltown and Gilberts Cove.

"It seems to be a bit of a unique event in terms of just the sheer numbers that are showing up dead," said Shawn Craik, a biology professor at Université Sainte-Anne.

'Thousands of fish'

On Friday, Craik took some students to the shore at Gilberts Cove. He said that in some spots, there were eight fish washed up in a square-metre block.

"If you extrapolate that over the entire beach, we're talking about thousands of fish," he said.

While there, he spoke with a clam fisherman who said that in his 40 years of clamming on the beach, he had never seen anything like this.

The Digby detachment of Fisheries and Oceans Canada began receiving calls from concerned citizens about the problem on Tuesday, said Gary Hutchins, the detachment's conservation and protection supervisor.

He said samples have been sent to Fisheries and Oceans Canada's lab in Moncton and the results are expected back the middle of next week.

"There could be several causes," said Hutchins.

He thinks it could be a parasite, a pollutant in the water or it could be a natural phenomenon such as a predator pursuing the herring into the St. Marys Bay area and forcing them onto the shore.

Craik said the situation is alarming given the role herring play as an important forage fish for species such as seabirds, whales and even cod, especially given their nutritional composition. The number of calories per gram of herring is much higher than most other forage fish.

Scavenging birds

"If we're losing our herring, then these animals have to go to second or third best [sources], which may offer a lot less energy," said Craik.

While most of the bodies of the herring are intact, some are being eaten by scavenging birds. The fact so many herring remain intact on the beach is an indication of their abundance.

"The likelihood of a fish persisting on a beach for any length of time is pretty small, unless the local scavenger population is full," said Ted Leighton, an adjunct biology professor at Université Sainte-Anne.

Leighton and Craik dissected some of the herring and didn't see any signs of disease.

One of the perplexing things to Leighton is that if the cause is a pollutant in the water, then other species should have been affected.

"That could knock out a whole a lot of fish. It usually also has secondary effects on other species, which we haven't seen. We haven't seen dead birds, dead seals and dead everything else on the beach," said Leighton.

That being said, he isn't ruling out a pollutant.

Whatever the cause, the problem remains.

"The process seems to be continuing because there are new dead and dying fish arriving with each tide, so something is happening out there in the waters of St. Marys Bay," said Leighton.