Salmon viruses, bacteria surveyed in Eastern Canada for first time

This plamu study would not have been possible without the contribution of Listuguj Fishers and the Listuguj Fisheries Science Team. This research project was a collaborative effort between GMRC, Listuguj Fisheries, ASF and researchers based in British Columbia, Newfoundland and Quebec.

Analysis of tissue samples from 150 Atlantic salmon has given scientists a first look at the viruses, bacteria, and microparasites that are infecting wild and aquaculture-origin Atlantic salmon in Eastern Canada and at sea. The findings were published this month in the journal Facets and document the detection of 14 infectious agents, including five not previously described as occurring in the region.

Tissue samples were collected in 2016 and 2017 from Atlantic salmon at five different sites: two in New Brunswick, one in Quebec, and two in Greenland. The New Brunswick sites included aquaculture escapees removed from the Magaguadavic River and wild and hatchery origin salmon from the nearby St. John River. In Quebec, fishermen at Listuguj First Nation on the Restigouche River provided wild origin samples from their fishery, while in Greenland, samples from North American and European origin salmon were collected from traditional food markets in the communities of Paamiut and Maniitsoq.

Samples collected from returning adults in the St. John and Restigouche showed a high degree of infectious agent similarity. For example, St. John River salmon, an endangered population where individuals were non-lethally sampled by clipping a small fragment of gill tissue, had six different infectious agents. All of those, plus three additional agents, were found in the Restigouche fish, which had gill, heart, and kidney tissue examined.

Neither PRV nor ISAV was detected in the St. John and Restigouche sampled adults and proximity to open net-pen aquaculture sites was not found to have an influence on infection profiles.

Infectious agents can have profound effects on the health of host species, especially in poor conditions, like warm water. However, little is known about the current and potential role of disease in the decline of wild Atlantic salmon.

This novel analysis of viruses, bacteria, and microparasites affecting Atlantic salmon in Eastern Canada provides a baseline and has identified several opportunities for future research on pathogen transmission among wild and aquaculture salmon and between European and North American populations at sea.

The full open-access study is found here: https://www.facetsjournal.com/doi/10.1139/facets-2019-0048