Using mark-recapture techniques to assess factors affecting survival of fall stocked walleye Sander vitreus in two Iowa lakes

Grausgruber, Emily E.; Weber, Michael J.

doi:10.1016/j.fishres.2021.106029

Cited by 6 publications

(10 citation statements)

References 35 publications

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“…In three Wisconsin hatcheries during 2019–2020, it was histologically determined that sex ratios of EGW were skewed towards females (60–100% female). One of the primary goals of the Wisconsin Walleye Initiative is to rehabilitate formerly naturally reproducing Walleye populations through the stocking of EGW, which are presumed to have higher survivorship than fry or small fingerlings in the wild (Grausgruber and Weber 2020, 2021a, 2021b). However, EGW mortality has been shown to be relatively high poststock out and pellet‐reared EGW did not adjust to natural prey as rapidly as fry (Grausgruber and Weber 2021a, 2021b).…”

Section: Discussionmentioning

confidence: 99%

“…One of the primary goals of the Wisconsin Walleye Initiative is to rehabilitate formerly naturally reproducing Walleye populations through the stocking of EGW, which are presumed to have higher survivorship than fry or small fingerlings in the wild (Grausgruber and Weber 2020, 2021a, 2021b). However, EGW mortality has been shown to be relatively high poststock out and pellet‐reared EGW did not adjust to natural prey as rapidly as fry (Grausgruber and Weber 2021a, 2021b). Biased sex ratios create a challenge when attempting to rehabilitate former naturally reproducing Walleye populations, particularly when natural recruitment failures have been persistent for many years.…”

Section: Discussionmentioning

confidence: 99%

“…Walleye Sander vitreus are an important subsistence, commercial, and recreational species throughout their native range, and stocking is a common management tool used to create fishing opportunities, maintain populations, and restore natural recruitment. Walleye stocking is commonly conducted with fry or small fingerlings; however, more recent propagation efforts have focused on raising extended growth Walleye fingerlings (EGW) in Iowa, Michigan, Minnesota, and Wisconsin based on the assumption that a larger hatchery product would equate to higher survivorship in the wild (Grausgruber and Weber 2021a, 2021b). In this case, small fingerling Walleye are transferred into lined and unlined rearing ponds during mid‐summer, finished with minnow forage (e.g., Fathead Minnow Pimephales promelas or natural forage), and stocked out in fall at lengths of about 150–230 mm.…”

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confidence: 99%

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Female Sex Ratio Bias in Extended Growth Hatchery Walleye Fingerlings Produced in Wisconsin

et al. 2022

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Sex differentiation in teleost fish is complex and often dictated by genetics, environmental conditions, and population density during critical embryonic/larval development periods. Walleye Sander vitreus have a long propagation and stocking history, and sex ratios of hatchery‐reared Walleye have been variable, typically skewed towards males, and potentially influenced by temperature. In contrast to previous fry and small fingerling Walleye stocking in Wisconsin water bodies, the Wisconsin Walleye Initiative of 2013 focused on the production of extended growth Walleye fingerlings (EGW) stocked out in fall under the assumption of greater survivorship and in response to observed declines in Walleye natural recruitment. Observed sex ratios of adult Walleye in a stocked northern Wisconsin lake chain were suggestive of EGW sex ratios skewed towards females. This lake chain has been under rehabilitation and an aggressive EGW stocking regime due to prolonged Walleye natural recruitment failures. To test whether imbalances in EGW were occurring, we collected 30 EGW from one Wisconsin hatchery in 2019 and about 50 EGW from each of three Wisconsin hatcheries in 2020 to histologically determine sex ratios. In 2019, EGW were about 97% female. In 2020, the percentage of females in hatchery samples ranged from 60% to 100%. Nonfemales in 2019 and 2020 were all undifferentiated. Our results suggest that EGW raised in Wisconsin under similar incubation and rearing protocols may be skewed towards females. If sex ratios of EGW are skewed towards females, the use of EGW may hinder efforts to rehabilitate natural recruitment. A deductive experimental and observational framework will be used to test for mechanism(s) influencing the high percentage of females in the hatchery product to inform protocols to better balance sex ratios.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Female Sex Ratio Bias in Extended Growth Hatchery Walleye Fingerlings Produced in Wisconsin

et al. 2022

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“…cost to creel). Extended rearing has also been implicated in high mortality through transport stress and difficulties in acquiring forage in the natural environment (Grausgruber & Weber, 2021a, 2021b).…”

Section: Discussionmentioning

confidence: 99%

Density‐dependent and environmental influences on juvenile walleye Sander vitreus (Mitchill) survivorship in northern Wisconsin lakes

Zebro

Mrnak

Shaw

et al. 2022

Fisheries Management Eco

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Walleye, Sander vitreus (Mitchill), natural recruitment has declined in northern Wisconsin lakes over time. Age-0 and age-1 walleye relative abundance (catch per unit effort; CPE) data from northern Wisconsin (1986-2019) were used to test for abiotic (i.e. lake characteristics and temperature variables) and biotic (age-0 and age-1 CPE) factors influencing age-0 to age-1 walleye mortality. Age-0 to age-1 walleye mortality was elevated at high age-0 CPE and variable at low age-0 CPE, which indicated strong density-dependence. Environmental factors such as spawning and ontogenetic phenology (climate change and ice-off dates), trophic mismatches, and metabolic and consumptive demand influenced age-0 to age-1 walleye mortality less strongly. Elevated age-0 to age-1 walleye mortality at low age-0 CPE supports previous findings of depensatory recruitment dynamics in northern Wisconsin walleye populations.

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“…populations, due in part to predation on wild and stocked Walleye (Rahel 2000;Jeppesen et al 2010;Kelling et al 2016). Declining Walleye populations are associated with increases in Largemouth Bass M. nigricans populations (Nate et al 2003;Fayram et al 2005;Hansen et al 2015b), and Largemouth Bass predation on stocked Walleye can negatively affect stocking success (Freedman et al 2012;Grausgruber and Weber 2021).…”

Section: Introductionmentioning

confidence: 99%

Smallmouth Bass and Walleye predation on stocked age‐0 Walleye in Lake Oahe, South Dakota

Olivencia,

Grausgruber,

Fincel

et al. 2024

N American J Fish Manag

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ObjectiveWalleye Sander vitreus are important sport fish that are commonly stocked to supplement populations. Increases in Smallmouth Bass Micropterus dolomieu abundance have prompted concerns regarding potential predation by these and other piscivores on stocked Walleye. Our objectives were to assess the timing and duration of predation on stocked Walleye, the frequency of occurrence and percent composition of Walleye in predator diets, and the percentage of stocked Walleye consumed.MethodsWe collected Smallmouth Bass, adult Walleye, Largemouth Bass M. nigricans, and Northern Pike Esox lucius diets in May (prestocking) and June–September (poststocking) 2019 and 2021 from three bays in Lake Oahe, South Dakota. We stocked two bays with Walleye (30–32 mm; 255–1649 Walleye/ha), whereas one bay was unstocked and served as a reference. We estimated Smallmouth Bass population abundance using Schnabel capture–recapture models, and we used bioenergetics to estimate the percentage of stocked age‐0 Walleye consumed.ResultWe found age‐0 Walleye in up to 11.4% of Smallmouth Bass diets and 14.6% of adult Walleye diets during the poststocking period. A single Largemouth Bass consumed one Walleye at 3 days poststocking (DPS), whereas we did not identify Walleye in Northern Pike diets. Daily mean percent composition by weight (±95% confidence interval) of age‐0 Walleye in diets peaked at 43.2 ± 35.1% at 3 DPS for Smallmouth Bass and 49.8 ± 97.7% at 14 DPS for adult Walleye. Following the peaks, age‐0 Walleye percent composition by weight rapidly declined and was generally 0% after 25 DPS. Smallmouth Bass abundance was 0.4–5.6 fish/ha, whereas recaptures of other predator species were insufficient for reliable population estimates. We estimated that Smallmouth Bass consumed 29,930 age‐0 Walleye in 2019 and 12,535 age‐0 Walleye in 2021 (up to 14.7 ± 4.7% of stocked fish), potentially representing an important source of stocking mortality.ConclusionOur research provides insights into the effects of poststocking predation on age‐0 Walleye by Smallmouth Bass and, to a lesser extent, Walleye, Largemouth Bass, and Northern Pike. Managers should consider predation on stocked fingerling Walleye from resident predators and should contemplate alternative stocking locations or timing to reduce potential predation.

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Using mark-recapture techniques to assess factors affecting survival of fall stocked walleye Sander vitreus in two Iowa lakes

Cited by 6 publications

References 35 publications

Female Sex Ratio Bias in Extended Growth Hatchery Walleye Fingerlings Produced in Wisconsin

Female Sex Ratio Bias in Extended Growth Hatchery Walleye Fingerlings Produced in Wisconsin

Density‐dependent and environmental influences on juvenile walleye Sander vitreus (Mitchill) survivorship in northern Wisconsin lakes

Smallmouth Bass and Walleye predation on stocked age‐0 Walleye in Lake Oahe, South Dakota

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