Juvenile Chinook Salmon Mortality in a Snake River Reservoir: Smallmouth Bass Predation Revisited

Erhardt, John M.; Tiffan, Kenneth F.; Connor, William P.

doi:10.1002/tafs.10026

Cited by 10 publications

(29 citation statements)

References 39 publications

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“…At a minimum, the p-value estimates represent an index of smallmouth bass feeding intensity, which shows their response to increased prey and its short duration. Most of these fish did not feed on many prey but typically on 1-2 large sand rollers that represented up to 51% of their body size, similar to relative prey sizes found by Erhardt et al (2018;up to 54%). above C max ).…”

Section: Discussionmentioning

confidence: 99%

“…Laboratory analyses of smallmouth bass stomach contents followed those of Erhardt et al (2018). In brief, all smallmouth bass diets were identified to lowest practical taxon and weighed (±0.001 g wet); prey fish were identified to species using diagnostic bones (e.g.…”

Section: Smallmouth Bass Dietmentioning

confidence: 99%

“…Supplementation of the natural population with hatchery-reared fish began in 1995 as a recovery measure, and about 2.5 million fish are released into the Snake River annually (FPC, 2018). The small size of age-0 Chinook salmon (~38-90 mm FL) makes them particularly vulnerable to predation (Erhardt, Tiffan & Connor, 2018;Fritts & Pearsons, 2006). The small size of age-0 Chinook salmon (~38-90 mm FL) makes them particularly vulnerable to predation (Erhardt, Tiffan & Connor, 2018;Fritts & Pearsons, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The small size of age-0 Chinook salmon (~38-90 mm FL) makes them particularly vulnerable to predation (Erhardt, Tiffan & Connor, 2018;Fritts & Pearsons, 2006). As opportunistic feeders, their high consumption rates have resulted in large numbers of age-0 Chinook salmon being lost to predation (Connor et al, 2015;Erhardt, St. John, Bickford, Rhodes & Tiffan, 2014;Erhardt et al, 2018). As opportunistic feeders, their high consumption rates have resulted in large numbers of age-0 Chinook salmon being lost to predation (Connor et al, 2015;Erhardt, St. John, Bickford, Rhodes & Tiffan, 2014;Erhardt et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Snake River fall Chinook salmon primarily adhere to an ocean-type life history (Healey, 1991), whereby fish emerge from the gravel in spring and rear in main-stem habitats for 2-4 months before moving seaward as age-0 migrants (Connor, Burge, Waitt & Bjornn, 2002). The small size of age-0 Chinook salmon (~38-90 mm FL) makes them particularly vulnerable to predation (Erhardt, Tiffan & Connor, 2018;Fritts & Pearsons, 2006). Smallmouth bass, Micropterus dolomieu Lacepѐde, are nonnative and the most abundant predator in the lower Snake River (Naughton, Bennett & Newman, 2004;Zimmerman & Parker, 1995).…”

Section: Introductionmentioning

confidence: 99%

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Post‐release predation mortality of age‐0 hatchery‐reared Chinook salmon from non‐native smallmouth bass in the Snake River

Erhardt

Tiffan

2018

Fisheries Management Eco

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Release of age‐0 hatchery‐reared fall Chinook salmon, Oncorhynchus tshawytscha (Walbaum), in the Snake River resulted in up to 30‐fold increases in salmon consumption by non‐native smallmouth bass, Micropterus dolomieu Lacepѐde. In an upper river reach, smallmouth bass fed intensively during a release in May, but Chinook salmon consumption returned to pre‐release levels within 1–2 days as hatchery‐reared fish quickly emigrated downstream. The predation response during a June release located farther downstream was dissimilar. Chinook salmon consumption increased to a lesser extent (11‐fold), lasted several days (~4) and no changes in feeding intensity were evident. Estimated numbers of age‐0 hatchery‐reared Chinook salmon lost to short‐term predation varied by year and study reach and ranged from 12,007 (6.03% of those released) to 210,580 (14.6% of those released) fish. Short‐term, intense feeding by smallmouth bass can contribute significantly to mortality of hatchery‐reared fish and should be considered when supplementing populations with hatchery juveniles.

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Section: Discussionmentioning

confidence: 99%

Section: Smallmouth Bass Dietmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Post‐release predation mortality of age‐0 hatchery‐reared Chinook salmon from non‐native smallmouth bass in the Snake River

Erhardt

Tiffan

2018

Fisheries Management Eco

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In hot water? Assessing the link between fundamental thermal physiology and predation of juvenile Chinook salmon

et al. 2022

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In light of ongoing environmental change, understanding the complex impact of interacting stressors on species, communities, and ecosystems is an important challenge. Many studies to date examine the effects of potential stressors on a single species of concern. Yet these effects often resonate throughout a community and may produce changes in ecosystem dynamics that are equally critical to species resilience. The aim of this study was to develop a mechanistic understanding of how a rapidly changing stressor, water temperature, will alter trophic interactions among ectothermic fish species. In our region, California's Sacramento–San Joaquin River Delta system, it has been speculated that the decreased survivorship of juvenile Chinook salmon (Oncorhynchus tshawytscha) in warming waters may be caused partly by increased predation. Temperature influences metabolic rate functions and the amount of energy available for fitness‐relevant parameters (i.e., swim performance and escape response). Consequently, we hypothesized that these patterns of predation emerge due to a physiological advantage of predators over prey at warmer temperatures. To explore this, our first objective was to determine the fundamental thermal physiology of juvenile Chinook salmon and their potential predators in the Delta. Three physiological performance traits were measured for each species across a spectrum of temperatures: aerobic scope, burst speed, and the ability to burst repeatedly. For our second objective, we assessed whether the effect of temperature on these performance traits predicted the outcome of predation trials conducted across the same temperature spectrum. We found that temperature effects were species or population specific. Additionally, absolute burst swimming ability and the relative burst performance between predator and prey were stronger indicators of trophic dynamics than aerobic scope. Our analyses also confirmed that a major predator in the Delta, specifically largemouth bass (Micropterus salmoides), is more thermally adapted to higher temperatures and will likely consume salmon with an increasing frequency as waters warm. Thus, we show that an improved understanding of how fundamental thermal physiology impacts predation can provide ecosystem managers with better tools to predictively model predation upon juvenile salmon based on prevailing and future water temperatures.

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Estimating predation rates of stocked juvenile Chinook Salmon using novel acoustic predation transmitters

Gravenhof,

Wuellner,

Renner

et al. 2024

N American J Fish Manag

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ObjectiveAcoustic telemetry is a tool commonly used to better understand the fates of fish following a stocking event. Until recently, predation on stocked fish could only be inferred by observing and identifying abrupt changes in tag detection histories. Recently, a novel predation transmitter has provided better insight into how predation affects poststocking survival. The main objective of this study was to use these transmitters to estimate predation rates on stocked juvenile Chinook Salmon Oncorhynchus tshawytscha in a landlocked system (Lake Oahe, South Dakota). Our secondary objectives were to determine how quickly predation was occurring, the time of day of predation events, and if there were differences in size between predated and nonpredated fish.MethodsIn 2021 and 2022, we surgically implanted Innovasea V5D 180‐kHz transmitters in 110 juvenile Chinook Salmon. These tagged Chinook Salmon were stocked at two locations on Lake Oahe along with a large cohort of untagged individuals. The tagged Chinook Salmon were passively tracked using an array of Innovasea VR2W 180‐kHz acoustic receivers.ResultAcross the two study years, we observed a mean predation rate (±SE) of 32.9 ± 6% on the tagged Chinook Salmon. Predation on the tagged Chinook Salmon occurred relatively quickly, with a mean time to predation of 86.7 ± 10.8 h. Additionally, 70% of the observed predation occurred during the daytime. Interestingly, results indicated that total length did not differ between fish that were preyed upon or and those that were, but there was a difference in total weight between the two groups.ConclusionOur results provide insight into recruitment bottlenecks within this population and offer information to other researchers regarding the advantages and limitations of this novel technology. Understanding how to mitigate predation could help to guide future stocking strategies to ensure a better return on investment for costly stocking programs.

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Juvenile Chinook Salmon Mortality in a Snake River Reservoir: Smallmouth Bass Predation Revisited

Cited by 10 publications

References 39 publications

Post‐release predation mortality of age‐0 hatchery‐reared Chinook salmon from non‐native smallmouth bass in the Snake River

Post‐release predation mortality of age‐0 hatchery‐reared Chinook salmon from non‐native smallmouth bass in the Snake River

In hot water? Assessing the link between fundamental thermal physiology and predation of juvenile Chinook salmon

Estimating predation rates of stocked juvenile Chinook Salmon using novel acoustic predation transmitters

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