Dams facilitate predation during Atlantic salmon (Salmo salar) smolt migration
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Abstract
Diadromous fish populations have incurred precipitous declines across the globe. Among many stressors, these species are threatened by anthropogenic barriers that impede movement, alter riverine habitat, and augment predator communities. In this study, we used acoustic transmitters (n = 220) with predation and temperature sensors to characterize Atlantic salmon (Salmo salar) smolt predation risk in the Penobscot River, Maine, USA. Across two seasons, we documented 79 predation events through a 170 km migratory pathway, which included three hydropower projects and a large estuary. We detected tagged smolts that were predated by fish (n = 42), marine mammals (n = 28), and birds (n = 9). Using a multistate mark-recapture framework, we estimated that 46% of smolts were predated during downstream migration, which accounted for at least 55% of all mortality. Relative predation risk was greatest through impoundments and the lower estuary, where on average, predation rates were 4.8-fold and 9.0-fold greater than free-flowing reaches, respectively. These results suggest that predation pressure on Atlantic salmon smolts is exacerbated by hydropower projects and that predation in the lower estuary may be greater than expected.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Dams facilitate predation during Atlantic salmon (Salmo salar) smolt migration |
| Series title | Canadian Journal Fisheries and Aquatic Sciences |
| DOI | 10.1139/cjfas-2023-0175 |
| Volume | 81 |
| Issue | 1 |
| Year Published | 2024 |
| Language | English |
| Publisher | Canadian Science Publishing |
| Contributing office(s) | Coop Res Unit Leetown |
| Description | 14 p. |
| First page | 38 |
| Last page | 51 |
| Country | United States |
| State | Maine |
| Other Geospatial | Penobscot River |
| Google Analytic Metrics | Metrics page |