Collapsed Atlantic salmon (Salmo salar) populations in the inner Bay of Fundy (iBoF) have been a concern for over three decades. Low early marine survival has been suggested as a cause of reduced returns of adult salmon. This study examined the survival of 25 migrant iBoF smolts/post-smolts from Gaspereau River, Kings County, to Minas Passage using high residency (HR) acoustic tags. Smolts took an average of 5.3 days post tagging to first be detected at the river mouth, and strongly favoured the ebbing tide for departure. On average, smolts took a further 3.0 days to reach Minas Passage where they were typically detected near the sea surface for several tidal cycles. At time of migration, temperatures averaged 14.0 °C in the river and 10.8 °C in Minas Passage. In-river survival was at least 96% and minimum survival was 95.8% from the river exit to Minas Passage. The short transmission interval of HR signals (2 s) contributed to a high probability that passing tags would be detected, suggesting that new HR tag technology may improve estimates of minimum survival, over traditional coded acoustic tags used in historic studies in this region. When examining survival estimates of migrating smolts/post-smolts, fisheries researchers introduce tag burden bias on fish. A “2%” ratio of tag-to-fish-weight has generally been accepted, however, achieving this on small bodies smolts can be challenging. This study also compiled and compared 82 data points of historic tag size and burdens in BoF and GoM region to provide context to better compare recent and historical estimates of smolt survival. Historical tag burden and size was significantly higher in the earliest studies (1994 – 1999) compared to all others, including present day (2015 – Present), since tags used then were on average 75% larger. An overall decreasing trend was observed and generally maintained in all bins from past to present. Results from this study provide survival estimates for this region and can be used for improved management.
Call Number
LE3 .A278 2024
Date Issued
2024
Supervisor
Degree Name
Master of Science
Degree Level
Masters
Degree Discipline
Affiliation
Abstract
Publisher
Acadia University