A tracking study of farmed Atlantic Salmon released from marine aquaculture sites located in the Fortune Bay area of Newfoundland and Labrador (Canada) to inform on sea recapture programs as a mitigation strategy

Abstract

In this study, we build on previous findings and simulate a salmon fall escape from two aquaculture sites located in a small cove representative of site locations in the South coast of Newfoundland (Canada). Under the previously established premise that recapture should be initiated almost immediately, the study was designed to focus on three main questions: 1) What is the amount of time fish spend in the small bay where they were released? 2) Are the adjacent small enclosed bays with aquaculture sites visited and for how long? 3) Are the depths where fish are detected conducive to their potential recapture? We measured fish movement (n = 60) during 17 days post-release. Results confirm quick responses required for any sea recapture effort to be successful knowing that the feasibility of immediate action following escapes remains logistically challenging. Our findings suggest that quickly targeting the direct site vicinity (within 2 days) as well as any adjacent coves (within 4 days) should be a priority in bays with similar configurations as Fortune Bay. The presence of aquaculture sites in production in these coves is likely a factor influencing the fish movement patterns but this needs to be confirmed by other trials. Fish were detected at depths >10 m indicating that gill nets of appropriate size and/or angling should be used.