Acoustic monitoring of wild fish interactions with aquaculture sites – phase 2

Description

This project was a continuation and expansion of a previously funded ACRDP project (17-P-01), which monitored wild fish interactions with Atlantic salmon farms using a high resolution imaging sonar and multi-frequency echo sounders. For the continuation of the project, experiments were repeated for two consecutive seasons to further assess the potential variations due to wild salmon juvenile species, ensuring that interactions at fully stocked fish farm facilities throughout the summer migration period are monitored.

To assess the timing and dynamics of wild salmon migration, and interactions of wild fish at aquaculture facilities, the two main objectives of this project were:

1. Monitor activity of wild fish in the direct vicinity of aquaculture sites using high resolution imaging sonar mounted on aquaculture facilities; and
2. Continue the monitoring of wild salmon migration in Okisollo channel using moored echo sounders close to the aquaculture facility.

Findings

Acoustic methods were used to assess the migration dynamics of wild, juvenile pacific salmon within the Discovery Passage of British Columbia and to assess their potential interaction with fish farms operating in the area. Autonomous echo sounders were placed in the Okisollo Channel, one of the pathways that wild juvenile salmon utilize in their out-migration to the open ocean. In both 2018 and 2019, juvenile salmon migrated from mid-May to early July, with half of the observed fish having moved through the area by June 10. There were more than twice as many salmon schools observed in 2019 than in 2018, but the overall pattern of migration was similar.

High-resolution imaging sonars were also installed on aquaculture facilities to detect and record animals that came within 10 m of the infrastructure. Observations from the imaging sonars were decoupled from the larger pattern of migration observed from the echo sounder. The number of fish detected was highly variable through the time-series. Less than 4% of the thousands of fish recorded inside the imaging sonar’s fields of view were observed for more than five seconds, suggesting rapid movement of fish through the area.

Program name

Aquaculture Collaborative Research and Development Program (ACRDP)

Years

Two years: 2018-2020

Principal investigator

Stéphane Gauthier, research scientist, Fisheries and Oceans Canada, Institute of Ocean Sciences, Pacific Region
Email: Stephane.Gauthier@dfo-mpo.gc.ca

Team members

Ben Snow, fisheries acoustician, Fisheries and Oceans Canada, Pacific Biological Station, Pacific Region
Stewart Johnson, research scientist, Fisheries and Oceans Canada, Pacific Biological Station, Pacific Region
Chrys-Ellen M. Neville, research biologist, Fisheries and Oceans Canada, Pacific Biological Station, Pacific Region
Marc Trudel, research scientist, Fisheries and Oceans Canada, St. Andrews Biological Station, Maritimes Region
Shani Rousseau, biologist, Fisheries and Oceans Canada, Pacific Biological Station, Pacific Region

Collaborators

Barry Milligan, Fish Health Director and veterinarian, Cermaq Canada Ltd.
Sharon DeDominicis, Regulatory Compliance and Certification Director, Marine Harvest Canada