Thanks to Darren Porter
DFO is working with partners such as the CFIA and ECCC to investigate the potential causes of the mass mortality of herring and some other species in several locations off SW Nova Scotia. The lab tests and analysis are being carried out related to:
• 1) Infection/disease,
• 2) Toxins (environmental, algal or other),
• 3) Predation, and
• 4) Water quality.
Work on the samples so far has included: necropsy with gross pathology, wet mounts of gill, intestine and skin, bacteriology, histopathology, virology and molecular testing (i.e. PCR) for ISA, IPN and VHS. Additional information on length, width and condition factor was also collected. No infections or infectious agents have been detected so far, after extensive testing. Some results are expected to be completed soon. Preliminary screening using a molecular test for viral disease agents are negative, however culture based viral assays are expected to be completed soon as well. No significant pathology was detected during microscopic examinations of tissue samples. Tests performed on blood samples indicated that the fish were not anemic and showed no evidence of viral agents.
The CFIA Dartmouth Laboratory has completed testing of herring samples for amnesic shellfish toxins (domoic acid), paralytic shellfish toxins (saxitoxins), and diarrhetic shellfish toxins. No toxins were detected in the samples. 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
Environment and Climate Change Canada are finalizing the analysis and results of testing for pesticides. ECCC also collected several water samples last week for testing with the assistance of DFO Conservation & Protection.
In addition to partner departments and agencies, DFO continues to collaborate with other parties to investigate potential causes. DFO will be having a conversation next week with individuals involved with some of the citizen science work in local communities.
Fish samples were also submitted to the Canadian Wildlife Health Cooperative at the Atlantic Veterinary College for health screening. Tests results will be provided to DFO when available.
No whale interactions with herring in the area have been detected to date. DFO’s Conservation and Protection frontline staff have conducted a total of four fly-overs to observe and report on the presence of whales with another flight planned for this week. DFO – Conservation and Protection continues to monitor the areas across SWNS for evidence of any incidents with confirmed occurrences to date ranging from St. Mary’s Bay to Tusket.
Dead fish found on the shoreline should not be collected by the general public and as always, consumers should only purchase fish products from licensed harvesters or licensed sellers.
DFO is aware of the dead lobsters, crabs, scallops, clams, starfish and herring that were reported on Monday, December 26th, near Savory Provincial Park, (Barton-Plympton), St Mary’s Bay. DFO will be examining the adjacent subtidal areas where dead herring have been found on shore.We don’t know at this stage whether or not the mortality of these invertebrates is associated with the mortality of herring that we have been monitoring. However, we will be continuing to focus our attention on possible environmental conditions.
The protection of Canada’s natural resources is a top priority of the Government of Canada. Stringent regulations are in place to protect both farmed and wild aquatic animals from disease. Marine finfish aquaculture sites are routinely monitored for fish health and are regulated both federally and provincially. No abnormalities or reportable diseases have been noted at sites in the area. Farms are also monitored for environmental performance with no significant effects noted at this time .