David Whorley, area manager of DFO in Yarmouth says scientists from DFO, the Canadian Food and Inspection Agency, federal Environment and the province of Nova Scotia are continuing to cooperate on the investigation.
“We are continuing to receive negative results from the screening they are doing, which is good news but we still haven’t found the cause,” he said.
The Department of Fisheries and Oceans began investigating Nov. 22 after several reports of dead and dying herring in the eastern end of St. Mary’s Bay.
And then Nov. 29, people started seeing the herring in the Annapolis Basin near Digby, Smith’s Cove and near Cornwallis.
[Thousands of dead herring in Annapolis Basin, Nov. 30]
DFO has confirmed reports of dead and dying herring near Pubnico as well.
Whorley says so far they have done gross pathology including autopsies, they have done bacteriology, they have examined the tissues of the fish and done virology, all of which turned up nothing.
They have tested for and ruled out both infectious salmon anemia virus and viral hemorrhagic septicemia.
Whorley says they are still working away on a list of usual suspects but some of the tests require culturing which could take another two weeks for results.
CFIA is also looking for traces of algal toxins like domoic acid, usually associated with shellfish, sardines and anchovies. That work is still ongoing.
Whorley says the fact that only herring have been impacted is also interesting and seems to indicate that oxygen depletion isn’t the cause.
DFO has done overflights to investigate the possibility of whales or tuna scaring the herring onto the beach and hasn’t found any evidence to point to that as the cause.
“The occurences are quite wide spread so it seems unlikely but we don’t know,” he said.
Whorley says people in southwest Nova Scotia have been great to report sightings and pass along information.
He hopes that will continue but would like to discourage people from collecting samples.
“We are happy with the level of community engagement but until we know what is behind this, we want to ask people to use an abundance of caution,” he said. “It is never a good idea to eat a dead animal you find on the beach and when it comes to collecting samples, people should leave that to us.”