Smallmouth bass (Micropterus dolomieu) and chain pickerel (Esox niger) identified as Atlantic salmon (Salmo salar) smolt predators in a reservoir system

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

Reservoir predation has been identified as a leading mortality source for smolts migrating through impounded river systems. We investigated smolt predation risk for an endangered Atlantic salmon (Salmo salar) population in the Weldon Dam reservoir in the Penobscot River, Maine, USA. In spring 2022, we characterized the fates of 390 tethered smolts. Smolts were exclusively predated by two predator species not native to the study area: chain pickerel (Esox nigern = 43) and smallmouth bass (Micropterus dolomieun = 42). Using Cox-proportional hazard analysis, we estimated that 23% (95% CI = 15%–29%) of tethered smolts were expected to be predated within a one-hour deployment. Water temperature was the primary driver of predation risk as predation probability increased from 10% to 33% when temperature increased from 5 to 15 °C. Smolts also incurred above-average predation risk when they were within 40 m of shore. We demonstrate that non-native fish predation may drive patterns of high impoundment mortality and that risk is spatially and temporally heterogeneous within these systems. Collectively, this study offers direct evidence of species-specific predation on Atlantic salmon smolts and illuminates potential strategies to mitigate predation risk during reservoir migration.

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Publication type Article
Publication Subtype Journal Article
Title Smallmouth bass (Micropterus dolomieu) and chain pickerel (Esox niger) identified as Atlantic salmon (Salmo salar) smolt predators in a reservoir system
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2024-0416
Volume 82
Publication Date April 17, 2025
Year Published 2025
Language English
Publisher Canadian Science Publishing
Contributing office(s) Coop Res Unit Leetown
Description 15 p.
First page 1
Last page 15
Country United States
State Maine
Other Geospatial Pensbscot River, Weldon Dam reservoir
Additional publication details