Passage through submersible and Archimedes pumps results in decreased migration survival in coho salmon yearlings
- 1Pacific Salmon Ecology and Conservation Laboratory, Faculty of Forestry and Environmental Stewardship, University of British Columbia, V6T 1Z4
Abstract
Flood-control pumpstations compromise connectivity and survival for migratory fish globally, yet field evaluations of modern "fish-friendly" designs remain scarce. We evaluated out-migration survival and behavior of yearling coho salmon (Oncorhynchus kisutch) entrained through an open-Archimedes screw station (Hammersley) and a conventional radial station (Barrowtown) in the lower Fraser River floodplain, British Columbia. Using acoustic telemetry over two migration seasons (2024-2025), we tracked smolts across an 84-km corridor to New Westminster and modeled apparent survival using a Cormack-Jolly-Seber framework. Baseline natural mortality in downstream controls averaged 60% across years (cumulative survival: ~40%). Entrainment through the conventional radial station caused 87.5% mortality. The open-Archimedes station conferred an improvement over the conventional facility but still induced 11.5% mortality. Notably, pump-induced losses at the Archimedes pump were predominantly latent: while acute survival through immediate tailrace receivers was high (95-98%), survival deficits diverged downstream in the mainstem Fraser River. Entrainment also prolonged out-migration, causing up to a 10-day delay in 2024 driven by forebay holding and depressed downstream transit speeds. Our findings demonstrate that while open-Archimedes screws improve survival relative to legacy radial impellers, they still impose substantial latent mortality. In heavily altered basins where baseline smolt mortality is already high, additive losses from drainage infrastructure may exacerbate survival bottlenecks.
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BibTeX
@misc{lingard2026passage,
title = {{Passage through submersible and Archimedes pumps results in decreased migration survival in coho salmon yearlings}},
author = {S. A. Lingard and H. Kinnard and A. Lotto and K. Szlachta and E. Eliason and E. Murphy and D. Straker and E. Martins and S. G. Hinch},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.14.751498},
url = {https://www.biorxiv.org/content/10.64898/2026.09.14.751498v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Passage through submersible and Archimedes pumps results in decreased migration survival in coho salmon yearlings
AU - S. A. Lingard
AU - H. Kinnard
AU - A. Lotto
AU - K. Szlachta
AU - E. Eliason
AU - E. Murphy
AU - D. Straker
AU - E. Martins
AU - S. G. Hinch
PY - 2026
DA - 2026/09/14
PB - bioRxiv
DO - 10.64898/2026.09.14.751498
UR - https://www.biorxiv.org/content/10.64898/2026.09.14.751498v1
AB - Flood-control pumpstations compromise connectivity and survival for migratory fish globally, yet field evaluations of modern "fish-friendly" designs remain scarce. We evaluated out-migration survival and behavior of yearling coho salmon (Oncorhynchus kisutch) entrained through an open-Archimedes screw station (Hammersley) and a conventional radial station (Barrowtown) in the lower Fraser River floodplain, British Columbia. Using acoustic telemetry over two migration seasons (2024-2025), we tracked smolts across an 84-km corridor to New Westminster and modeled apparent survival using a Cormack-Jolly-Seber framework. Baseline natural mortality in downstream controls averaged 60% across years (cumulative survival: ~40%). Entrainment through the conventional radial station caused 87.5% mortality. The open-Archimedes station conferred an improvement over the conventional facility but still induced 11.5% mortality. Notably, pump-induced losses at the Archimedes pump were predominantly latent: while acute survival through immediate tailrace receivers was high (95-98%), survival deficits diverged downstream in the mainstem Fraser River. Entrainment also prolonged out-migration, causing up to a 10-day delay in 2024 driven by forebay holding and depressed downstream transit speeds. Our findings demonstrate that while open-Archimedes screws improve survival relative to legacy radial impellers, they still impose substantial latent mortality. In heavily altered basins where baseline smolt mortality is already high, additive losses from drainage infrastructure may exacerbate survival bottlenecks.
ER -