An effective method for the recapture of escaped farmed salmon

Aquaculture Environment Interactions

Elina Halttunen¹  Jofrid Skarðhamar¹  Ove T. Skilbrei¹  Cedar M. Chittenden¹  Audun H. Rikardsen¹  Jan G. Davidsen¹  R. Scott McKinley¹ 

关键词: Acoustic telemetry;    Aquaculture;    Dispersal behaviour;    Migration;    Mitigation;    Net fishery;    Salmo salar;   

DOI  :  10.3354/aei00021

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

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.

【 授权许可】

Unknown