Research Document 2024/057
Updated Information on Atlantic Salmon (Salmo salar) Inner Bay of Fundy Populations (IBoF; part of Salmon Fishing Areas 22 and 23) of Relevance to the Development of a 2nd COSEWIC Status Report
By Reader, J.M., Hardie, D.C., McWilliam, S., Brunsdon, E.B., Notte, D. and Gautreau, M.
Abstract
The purpose of this research document is to provide an update of Fisheries and Oceans Canada (DFO) information for the Inner Bay of Fundy (IBoF) Atlantic Salmon (Salmo salar) population (Designatable Unit 15) to support the development of a second status report of Atlantic Salmon in eastern Canada by the Committee on the Status of Endangered Wildlife in Canada. Information pertaining to IBoF Atlantic Salmon populations within Salmon Fishing Areas 22 and 23 is compiled in this review, including population status, trends, life history characteristics, habitat and threats.
Abundance of IBoF Atlantic Salmon are presently at critically low levels, listed as endangered and protected under the federal Species at Risk Act. Persistence of the populations is currently maintained through a Live Gene Bank (LGB) program focused on three rivers: the Stewiacke and Gaspereau in Nova Scotia, and the Big Salmon in New Brunswick. IBoF salmon assessment and monitoring activities undertaken by DFO Science primarily on the Big Salmon and Gaspereau rivers over the last 20 years have been in association with the LGB program and all incorporate genetic analyses. Estimated adult abundance on the Big Salmon River is presently below 4% of its conservation requirement and estimated egg deposition has declined at a rate greater than 60% over the last three generations (13 years). Since 2006, annual egg depositions from sea-run returns to the Gaspereau River have never exceeded 10% of the conservation requirement. A great majority of adults returning to the Big Salmon River continue to mature as small salmon (<63 cm fork length) after one-sea-winter and include a high percentage of females but the occurrence of repeat spawners is much less prevalent than in earlier years (1960s and 1970s). The Gaspereau River population is comprised of a higher proportion of maiden two-sea-winter salmon compared to the Big Salmon River adult returns. Most adults returning to the Gaspereau are progeny of LGB releases whereas more than 75% of returns to the Big Salmon are from the residual wild population or of unknown origin. The mean return rate of combined origin small salmon to the Big Salmon River over the past 13 years is extremely low at 0.29%.
Overall, the recent available DFO data for IBoF Atlantic Salmon indicates that population abundance has not improved and may have further declined over the past three generations despite significant conservation and supplementation efforts. Given the current lack of recruits from natural spawning and very high marine mortality, the LGB program remains critical to population recovery when marine survival rates increase to a level where these populations can be self-sustaining.
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