Fish Mortality in Southwest Nova Scotia
On November 22, 2016, Fisheries and Oceans Canada (DFO) was notified of dead herring located on the shores of Gilbert Cove, St. Mary’s Bay, Nova Scotia. There were also early reports of dead herring in the parts of the Annapolis Basin (near the mouth of the Cornwallis River) but these were short-lived, isolated occurrences. In the days before and after Christmas, some invertebrates were also reported in this same 15 km stretch near Savory Provincial Park. DFO worked with partners such as the Canadian Food Inspection Agency (CFIA) and Environment and Climate Change Canada (ECCC) to investigate the potential causes of the mortality of herring and some other species in several locations off southwest Nova Scotia.
Last Updated: March 24, 2017
Dead herring found on shores should not be collected or consumed by the general public.
As always, consumers should only purchase herring from licensed harvesters or licensed sellers.
Current results have ruled out infection, viral diseases, physical injury and toxins as the cause of mortality.
What testing has been done?
DFO and its partners at the CFIA and ECCC have completed a number of tests to identify the potential causes of this mortality event. Lab tests and analysis were performed on causes related to infection or disease, toxins (environmental, algal or other), predation, and water quality.
The tests included:
- necropsy with gross pathology,
- wet mounts of gill, intestine and skin,
- molecular testing (i.e. PCR) for ISA, IPN and VHS ,
- amnesic shellfish toxins (also known as domoic acid),
- paralytic shellfish toxins (looked for 12 toxins including saxitoxin),
- diarrhetic shellfish toxins (looked for 31 toxins), and
- additional information on length, width and condition factor was also collected.
Scientific Test Results
At this time, the cause of herring mortality has not been determined.
After extensive testing, no infections or infectious agents have been detected in the herring samples. Tests performed on blood samples indicated that the fish were not anemic and showed no evidence of viral agents.
The CFIA conducted tests for a number of algal toxins and domoic acid, and no toxins were detected in the samples.
No significant pathology, or physical injury to the fish, was detected during microscopic examinations of tissue samples.
Scientists have also conducted testing on the Bay of Fundy, and preliminary results for temperature, salinity and dissolved oxygen came back normal.
Water samples showed nothing unusual in oxygen levels. ECCC samples were analyzed for the presence of metals, chemicals, toxins, and several other parameters. Test results came back normal, nothing unusual was identified.
CFIA also confirmed that Canadian Shellfish Sanitation Program sampling in the area is current and shows no evidence of toxins at levels that would have resulted in the mortality seen in this fish kill.
Surveys and Patrols
DFO actively monitored the situation. The Department’s Conservation and Protection frontline staff conducted a number of foot patrols in the area. No new wash-ups of herring and no evidence of invertebrates have been identified since January 2, 2017.
Status of Herring in the Bay of Fundy
Herring mortality does not appear to be increasing. Video surveys were conducted in subtidal areas for dead herring, however no evidence of dead herring or other species were found. There has been no evidence of mortality on the bottom of the bay. Acoustic surveys have observed several large schools of herring in the area.
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