The Department of Fisheries and Oceans says there is nothing out of the ordinary with the environment near where thousands of sea creatures washed up near Digby, N.S.
The distressing amount of sea life and diversity of species found dead on some beaches along the Bay of Fundy over the past few weeks has been puzzling. So far, tests haven't revealed what's killing the sea life.
Federal scientists went out on the water Thursday to examine the physical environment, taking water samples, testing dissolved oxygen, salinity and temperature — all of which were normal. They also scanned images of the bottom of St. Marys Bay off the Bay of Fundy. The video showed normal conditions with no masses of dead organisms that one would expect if the cause was an ongoing environmental problem.
"We have ruled out the usual suspects," said Kent Smedbol, manager of population ecology for DFO.
Smedbol said they've also consulted recent environmental data from the area. He said they don't have anything conclusive, but a recent winter storm caused a sudden drop in temperature, down to –5 C, in the shallow areas around Digby. He said that, combined with rough surf, could have caused bottom-dwelling sea creatures to die and wash up.
Problem not getting worse
"It is a little bit perplexing and now we're broadening out our analysis again, looking at things that might be less likely," said Smedbol.
Derreck Parsons, a senior compliance program officer for DFO, said whatever the cause, there doesn't appear to be any more dying fish.
"The good news for me is that it doesn't seem like the event is worsening," he said.
Dead or dying herring have been washing up on beaches since late November from Tusket, off southwest Nova Scotia, to the Annapolis River. On Boxing Day, scores of crabs, lobsters, starfish and other sea creatures were also found at a beach near Digby, N.S.
Parsons said the majority of dead fish have been found in St. Marys Bay between the Sissiboo River and Plympton.
Other potential causes ruled out
So far, scientists have found no evidence of disease, parasites or toxins.
"There was nothing outstanding about the herring. No physical trauma, no sign of widespread disease," said Smedbol.
"Nothing really that would stand out to be honest."
Work by the Canadian Food Inspection Agency, and Environment and Climate Change Canada to look for contaminants and by the fish health lab in Moncton has come back negative, Smedbol said.
Smedbol also said it's "highly unlikely" the tidal turbine that came online in November is responsible for two reasons. Firstly, if the turbine was responsible for the deaths, scientists would expect to see dead animals on more beaches in the area. Secondly, more fish species would likely be affected, other than herring.
If the problem was methane leaks causing a drop in oxygen, Smedbol also said more species of fish would be washing up, not just herring.
Nova Scotia's Department of Fisheries and Aquaculture said provincial veterinarians are also keeping a close eye on farmed fish in the area, with the most recent visit last week.
They haven't found any signs the scores of herring that have washed up have affected the farmed fish, said Heather Fairbairn, a spokeswoman for the department.
The Municipality of the District of Digby said there are no municipal sewer or water systems in the area where the fish have been found.