Spatial and temporal distribution and survival of farmed Atlantic salmon after experimental release from sea cage locations

Description

The expansion of the aquaculture industry in Newfoundland and the possible impacts escaped farmed salmon have raised questions about impacts to local wild salmon populations. Despite increased industry awareness and the implementation of a code of containment, escape events can still occur. Spawning between aquaculture-origin Atlantic salmon and wild Atlantic salmon has been scientifically documented in Canadian waters. Research is needed to better understand the potential risk of escapees on wild salmon populations.

The objective of this project was to determine the residency time, locations, migratory routes, and survival rates of escaped farmed Atlantic salmon by monitoring the movements of acoustically-tagged smolts, post-smolts, and adults, following a simulated escape of a group of fish at different times of the year. Identifying the migratory routes followed by escapees, as well as residency patterns and how they vary with the timing of the escape event (seasonal effects), informs the design of more efficient recapture strategies.

Study results can inform federal and provincial ecosystem-based management of the industry and provide key information for the development of strategies to minimize potential impacts of escaped farmed Atlantic salmon on the environment and wild salmon populations.

Findings

Research supported several other studies which indicate that recapture near the cage site is probably not feasible given the short time frames that escaped (released) fish remain in the area. Some success might be attained if recapture efforts occur over a larger area (i.e., >10 km from the release site in our study), within the first few weeks after release. Fish released in the spring exhibited a migratory behaviour highlighting the potential difficulty of recapture at that period of the year. It may be easier to capture a considerable proportion of fish that escape in late autumn (autumn and summer in our study) as opposed to spring.

This research was the first phase in documenting escapee movement to allow potential testing of recapture strategies. Recapture should be implemented as a last resort with a significant investment in containment technologies as a primary strategy.

Publications

Hamoutene, D., Cote, D., Marshall, K., Donnet, S., Cross, S.F., Hamilton, L., McDonald, S., Clarke, K. and Pennell, C. 2018. Spatial and temporal distribution of farmed Atlantic salmon after experimental release from sea cage sites in Newfoundland (Canada). Aquaculture 492:147-156.

Hamoutene, D., Costa, I., Burt, K., Lush, L. and Caines, J. 2015. Survival of farmed, wild and first generation hybrid Atlantic salmon (Salmo salar Linnaeus, 1758) to low temperatures following seawater transfer. Journal of Applied Ichthyology 31(2),:333-336.

Multimedia

Aquaculture research: Tracking released farmed salmon

Program Name

Program for Aquaculture Regulatory Research (PARR)

Year(s)

2014 to 2017

Principal Investigator(s)

Dounia Hamoutene
Research Scientist, Aquaculture Section, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region
Email: Dounia.Hamoutene@dfo-mpo.gc.ca

Team Member(s)

Brian Dempson, Research Scientist, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region

Keith Clarke, Biologist, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region

Curtis Pennell, Biologist, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region

Kimberley Burt, Biologist, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region

Lynn Lush, Biologist, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region

Geoff Perry, Aquaculture Management Division, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, Newfoundland and Labrador Region