Spatial variation in landlocked Atlantic Salmon smolt survival associated with dam passage, avian predation, and stocking location

Kurt C. Heim; William R. Ardren; Jonah L. Withers; Zachery Eisenhauer; Matthew A. Mensinger; Theodore Castro-Santos

doi:10.1093/najfmt/vqae002

Home/Archive/USGS

USGS · 70266489

Spatial variation in landlocked Atlantic Salmon smolt survival associated with dam passage, avian predation, and stocking location

Kurt C. Heim·William R. Ardren·Jonah L. Withers·Zachery Eisenhauer·Matthew A. Mensinger·Theodore Castro-Santos

View original source ↗Export metadata ↓

Abstract

Objective We evaluated survival differences between upstream and downstream stocking for landlocked Atlantic Salmon Salmo salar smolts in a tributary to Lake Champlain. Methods We radio-tagged smolts and stocked them concurrently with 22,000 smolts at two release sites in 2 years. The downstream location (DS, river kilometer 16, no dam passage) was a historically used site in a dam tailrace, whereas the upstream site (US, river kilometer 27, two dams to pass) was in a side channel and stocked for the first time. We estimated survival, counted birds during stocking, and searched nesting colonies for transmitters. Results Within stocking reaches, survival per kilometer for the DS release group was markedly lower than that for the US group (US 2021 and 2022 = 0.98, 0.98, respectively; DS 2021 and 2022 = 0.82, 0.69, respectively). At the DS site, we documented a tenfold increase in avian predators following stocking, whereas no increase was detected at the US site. Passage was >96% at both dams, but postpassage survival (per kilometer) was much lower at the second dam (2021 = 0.78, 2022 = 0.82) compared to the first dam (2021 = 0.96, 2022 = 0.97). Surprisingly, cumulative survival to Lake Champlain was higher for fish that were released upstream in 2022 (US = 43%; DS = 32%) despite dam passage and additional migratory distance. At least 20% (2021) and 7% (2022) of successful migrants were later consumed by birds in the river delta or in Lake Champlain. Conclusions Upstream stocking did not consistently result in lower cumulative survival, likely due to predators habituated to annually reoccurring stocking in a dam tailrace that increased stocking-related mortality at the DS release site. We highlight the importance of evaluating historically used stocking sites, as substantial loss of smolts could be avoided by simple changes to stocking practices. Avian predation was a major source of mortality, necessitating further studies to understand and address survival issues within Lake Champlain.

Explore related subjects

North American Journal of Fisheries Management Article

Source-reported bounding extent: 44.41013272582299° to 44.56259499841883° latitude; -73.25705156492046° to -72.9771968925503° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Kurt C. Heim, William R. Ardren, Jonah L. Withers, Zachery Eisenhauer, Matthew A. Mensinger, Theodore Castro-Santos. 2025-03-19. Spatial variation in landlocked Atlantic Salmon smolt survival associated with dam passage, avian predation, and stocking location. https://doi.org/10.1093/najfmt%2Fvqae002

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Biological, environmental, and geomorphological factors influencing reach-specific survival of spring Chinook Salmon smolts upstream of the Columbia–Snake River hydrosystem

Objective Pacific salmon Oncorhynchus spp. are exhibiting catastrophic declines throughout much of the Pacific Northwest, and juvenile mortality contributions are disproportionately high. Many Pacific salmon smolt populations are exhibiting high natal stream mortality; however, detailed natal stream reach-specific survival knowledge is lacking. Our objectives were to estimate natal stream reach-specific survival and identify influential covariates for spring Chinook Salmon O. tshawytscha smolts. An additional objective was to evaluate (i.e., estimate postrestoration cumulative survival) a novel and strategic large-scale river restoration approach (i.e., stream confluence restoration) in two Pacific Northwest spring Chinook Salmon natal streams. Methods Using radiotelemetry techniques during March–June (2011–2017), we estimated natal stream reach-specific survival for spring Chinook Salmon smolts in Catherine Creek and the Grande Ronde River, northeast Oregon. We examined the interrelated influences of temporal, biological, environmental, and geomorphological covariates on the behavior, travel time, and reach-specific survival of spring Chinook Salmon smolts that were emigrating through two hydrologically altered natal streams in the interior Columbia River basin. For each natal stream smolt tag-group, Cormack–Jolly–Seber reach-specific survival estimates that were adjusted for premature tag failure (i.e., bias-corrected) were generated. Subsequently, smolt effects were estimated using reach-specific travel times and survival estimates coupled with individual time-varying covariates from radio-tagged smolts and occupied reaches using an existing predator–prey model (i.e., mean free-path length [ XT ] model). Complementary population-specific principal coordinate analyses (PCoAs) were conducted to facilitate visualization of multicovariate resemblances in ordination space. Last, we employed our best-fitting XT model to model cumulative changes in smolt survival that were associated with a large-scale stream channel restoration scenario (i.e., restoration of the historical Catherine Creek and Grande Ronde River confluence). Results In aggregate, Catherine Creek smolts exhibited high mortality throughout Catherine Creek but near-100% survival upon entering the Grande Ronde River. In contrast, Grande Ronde River smolts generally exhibited low mortality upstream from the Grande Ronde Valley and high mortality throughout the Grande Ronde Valley. Our best-fitting XT model indicated that smolt survival was positively correlated with discharge, body size, and current velocity but negatively correlated with avian predation. Natural-origin smolts from Catherine Creek displayed higher λ-values (i.e., distance between predator–prey encounters) than their significantly larger and faster emigrating hatchery conspecifics, indicating that hatchery smolts may be more susceptible to predation. Our population-specific PCoAs further revealed that novel water (i.e., unique water chemistry) and emigration rate were the strongest predictors of reach occupancy in multivariate ordination space. Under a stream restoration scenario of restoring the historical hydrological template (i.e., restored channel configuration), our best-fitting XT model predicted changes in population-specific cumulative survivals to the lower Grande Ronde Valley (Imbler, Oregon) ranging from −38.4% to 69.0% for Grande Ronde River and Catherine Creek spring Chinook Salmon smolts, respectively. Conclusions Our best-fitting XT model and PCoAs identified the relative importance of biological, environmental, and geomorphological factors to both natural- and hatchery-origin Chinook Salmon smolt survival in two neighboring interior natal streams in the Columbia River basin. Our research indicates that concurrent habitat restoration and fish management strategies, including focused attention on smolt-rearing nursery habitat restoration, piscivorous avian control plans, adaptive management strategies for hatchery smolt releases, and discharge and novel water regime restoration projects, may yield survival benefits to “in-basin” Chinook Salmon smolts. Our research can inform origin-type-specific Chinook Salmon smolt management, habitat restoration, and future research decisions throughout the upper Grande Ronde River subbasin and potentially the Pacific Northwest.

Oregon, Washington↗

USGS2026

Effect of rotenone treatment on alpine stream invertebratecommunities in Colorado

Objective: Introduction of non-native salmonids to western United States streams has resulted in extirpation and even extinction of native cutthroat trout. Once thought to be extinct, a genetically verified population of Greenback Cutthroat Trout (GBCT) Oncorhynchus virginalis stomias was identified and used for population re-establishment efforts. To restore native trout habitat, stream reaches above a dispersal barrier are typically treated with a piscicide (i.e., rotenone) to remove non-native trout before reintroduction of natives. One concern with this method is the possible impact to non-target invertebrates, which are an important food source for trout, and a drastic disturbance to invertebrates following rotenone treatment could negatively affect native trout establishment. Methods: Two alpine streams were treated with liquid rotenone via drip stations during two consecutive days. Invertebrate communities were sampled for six years in two streams where GBCT was reintroduced. Pre- and posttreatment sampling allowed for examination of short-term, intermediate, and long-term responses to invertebrate communities. Results: Negative short-term responses were detected for total taxa richness, EPT richness, and percent Heptageniidae density immediately following rotenone application. However, most community metrics returned to pretreatment values within 1 to 2 years posttreatment. Invertebrate community changes between pretreatment and 3 to 5 years posttreatment were observed with increased percent Chironomidae density and decreased percent EPT (Ephemeroptera, Plecoptera, Trichoptera) density. Conclusion: This study provides insight into invertebrate community response to rotenone treatment in high alpine streams and adds to the current literature which displays short-term declines in invertebrates following rotenone and recovery of most aspects of the initial invertebrate community within one year posttreatment. Lay Summary Rotenone application for cutthroat trout habitat restoration negatively affected invertebrate communities in the 1 to 2 months following treatment; however, most community values recovered to pretreatment levels within 1 to 2 years. Keywords: native fish, cutthroat trout, fish management, invertebrate community, habitat restoration

Colorado↗

USGS2026

Putting weight to work: A review and examples of weight-based indicators in freshwater fish stock assessment

Despite being a direct measure of biomass and central to fisheries management, weight-based metrics remain underutilized in freshwater fish stock assessment. Here, we present a concise review of the application of weight in evaluating freshwater fish populations. We examine the historical use of weighing, assess how weight is applied across subdisciplines of freshwater fish science, contrast weight- and length-based approaches, and identify biases in their application. We then synthesize weight-based metrics, indices, and models within four broad categories—population and community weight structure; condition, growth, and efficiency; reproductive potential and production; and yield and exploitation dynamics—highlighting approaches that inform fish ecology, population and community dynamics, and vital rates. We conclude by identifying key opportunities and methodological innovations needed to expand the effective use of weight-based metrics in freshwater fish conservation and management.

North American Journal of Fisheries Management↗