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Aquaculture Environment Interactions

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AEI 1:215-224 (2011)  -  DOI:

An effective method for the recapture of escaped farmed salmon

Cedar M. Chittenden1,2,*, Audun H. Rikardsen1, Ove T. Skilbrei3, Jan G. Davidsen1,4, Elina Halttunen1, Jofrid Skarðhamar3, R. Scott McKinley2

1Department of Arctic and Marine Biology, University of Tromsø, 9037 Tromsø, Norway
2The University of British Columbia, Centre for Aquaculture and Environmental Research, 4160 Marine Drive, West Vancouver, British Columbia V7V 1N6, Canada
3Institute of Marine Research, 5817 Bergen, Norway
4Museum of Natural History and Archaeology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway

ABSTRACT: The search for effective strategies to prevent and mitigate accidental releases of aquaculture fishes is on-going. To test a new recapture strategy and evaluate the individual dispersal behaviour of escaped farmed Atlantic salmon Salmo salar L. at the northern limit of its range, 39 adult salmon (mean ± SD fork length and weight: 85.5 ± 5.0 cm and 7.4 ± 1.4 kg, respectively) were implanted with depth-sensing acoustic tags and released in a north Norwegian fjord during the spring of 2007. The fish were released from 2 aquaculture sites in the Altafjord system and tracked using both mobile and fixed receivers. The coastal marine bag-net fishery, in combination with in-river angling, was tested as a potential recapture strategy. Immediately following the simulated escape event, the fish dove to near-bottom depths, subsequently returning to surface levels within the following days. The fish dispersed rapidly (9.5 ± 19.2 km d–1), traveling outward to coastal waters along the edges of the fjord. The bag-net fishers and anglers recaptured 79% of the escaped fish within 1 mo post-release, 90% of which were from bag nets. While most of the fish left the fjord, 7 tagged fish (18%) entered the Alta River estuary (3 of which later migrated up the Alta River), and 1 returned to the Altafjord the following year, presumably to spawn. The results showed that recapture efforts need to be immediate and widespread to mitigate farm-escape events. Coastal bag nets were effective at recapturing escaped farmed salmon, compared to previously tested methods, and would be especially useful in areas where gill-netting is not permitted.

KEY WORDS: Acoustic telemetry · Aquaculture · Dispersal behaviour · Migration · Mitigation · Net fishery · Salmo salar

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Cite this article as: Chittenden CM, Rikardsen AH, Skilbrei OT, Davidsen JG, Halttunen E, Skardhamar J, Scott McKinley R (2011) An effective method for the recapture of escaped farmed salmon. Aquacult Environ Interact 1:215-224.

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