Salvage using electrofishing methods caused minimal mortality of burrowed and emerged larval lampreys in dewatered habitats

Harris, Julianne E.; Liedtke, Theresa L.; Skalicky, Joseph J.; Weiland, Lisa K.

doi:10.1002/nafm.10894

Cited by 3 publications

(33 citation statements)

References 36 publications

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“…Like laboratory findings, a field evaluation of salvage techniques reported that the mortality risk for larval lampreys declined significantly with increased size (Harris et al. 2023). Taken together, these findings highlight the vulnerability of small lampreys to dewatering.…”

Section: State Of the Sciencementioning

confidence: 95%

“…2021; Harris et al. 2023). Laboratory and field research suggests that survival associated with a dewatering event varies based on larval size, whether the larvae exhibit emergence, the duration of exposure, and environmental conditions (Liedtke et al.…”

Section: State Of the Sciencementioning

confidence: 99%

“…The study tested an intensive salvage treatment (based on LTWG recommendations) that exposed larvae to several potential salvage impacts. To create a salvage experience with a perceived high risk of mortality, the study applied a salvage treatment that included multiple rounds of electrofishing that targeted bony fishes, multiple rounds of LSEF (in wet and dry conditions), and foot pressure associated with personnel walking on dewatered substrates (Liedtke et al 2021;Harris et al 2023). Any of these salvage activities could negatively impact larvae, and as they are commonly used in combination, the cumulative effects could be substantial.…”

Section: Evaluations Of Salvage Proceduresmentioning

confidence: 99%

“…Mortality from exposure to dewatering and the salvage treatment was not more than 6% when mean air temperature was <18°C (mean water temperature ≤12°C), whereas mortality was 20% when mean air temperature was 36°C (mean water temperature = 20°C; Harris et al. 2023). Larval lampreys have a high tolerance for changing water temperatures, but temperatures above 18–20°C can cause behavioral effects (e.g., slowed burrowing) and mortality occurs at around 28–30°C (Meeuwig et al.…”

Section: State Of the Sciencementioning

confidence: 99%

“…Salvage activities themselves appear to cause minimal mortality (Harris et al. 2023), and thousands of larval lampreys have been relocated (Lampman and Beals 2019; Skalicky 2021), which suggests that salvage may have a positive impact on local larval populations. However, questions remain about the magnitude of contributions from salvage compared to other conservation actions, such as improving or increasing spawning and rearing habitats.…”

Section: Critical Uncertaintiesmentioning

confidence: 99%

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Synthesis of larval lamprey responses to dewatering: State of the science, critical uncertainties, and management implications

Liedtke

Harris

Blanchard

et al. 2023

N American J Fish Manag

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Dewatering of fine sediments in rivers and streams can kill many thousands of larval lampreys (Order Petromyzontiformes) burrowed in these habitats. The larval life stage for lampreys lasts 3‐ 10 years, and because larvae often aggregate in large numbers, negative impacts from dewatering could potentially deplete local populations and affect multiple year classes. Larval lampreys have not traditionally been considered during in‐stream projects, but recent efforts to increase awareness of lamprey habitats have resulted in guidance on dewatering approaches to limit impacts to lampreys. Salvage efforts to rescue and relocate lampreys aim to mitigate losses, but a lack of understanding of lamprey responses limits optimization of dewatering and salvage procedures. We summarize the state of the science for nine factors that influence larval lamprey (Entosphenus and Lampetra spp.) responses to dewatering, including: burrowing depth, the prevalence and timing of emergence, movements, survival, and the influence of slope, dewatering rate, light, and lamprey size. Research suggests that shoreline slope influences movement capability; hot and sunny conditions increase the risk of mortality; salvage activities cause minimal direct mortality; and smaller larvae are especially vulnerable to negative impacts from dewatering because they are more likely to emerge and are less capable of movement. Critical uncertainties associated with dewatering include cues that drive emergence, influence of sediment composition and stratigraphy, vertical distribution of larvae in natural settings, use of the hyporheic zone, the scale of predation losses, and the effectiveness and impacts of salvage activities. Balancing investments in salvage efforts and lamprey exclusion efforts (e.g., screening) and developing field survey approaches to evaluate use of the hyporheic zone by lampreys are identified management implications and research needs. Addressing the critical uncertainties discussed here and providing updated, science‐based guidance on dewatering and salvage practices are suggested management actions to support lamprey conservation.

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Section: State Of the Sciencementioning

confidence: 95%

Section: State Of the Sciencementioning

confidence: 99%

Section: Evaluations Of Salvage Proceduresmentioning

confidence: 99%

Section: State Of the Sciencementioning

confidence: 99%

Section: Critical Uncertaintiesmentioning

confidence: 99%

See 3 more Smart Citations

Synthesis of larval lamprey responses to dewatering: State of the science, critical uncertainties, and management implications

Liedtke

Harris

Blanchard

et al. 2023

N American J Fish Manag

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Shoreline slope influences movements of larval lampreys over dewatered substrate

Liedtke,

Harris,

Gray

2024

Aquaculture Fish & Fisheries

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Larval lampreys are filter feeders that live for several years burrowed in fine sediments in freshwater streams. Stream side channels and edges, where larval lampreys gather, are vulnerable to natural and human‐caused dewatering. Water level reductions can strand and kill thousands of larval lampreys, in part because many remain burrowed until their habitats are exposed, at which point larvae must emerge and attempt to move over dewatered substrate to locate wetted habitat. Dewatering for restoration efforts or seasonal closures of irrigation canals can be done slowly to reduce lamprey strandings, but in some settings, mechanisms are lacking to control the dewatering rate. Phased dewatering, where water level is reduced in stages separated by periods of static water level, could provide options when dewatering rate cannot be tightly controlled. To guide this phased approach, information is needed on the movement capability of larval lampreys. We examined larval lamprey (Entosphenus tridentatus and Lampetra spp.) movement distance and rate over dewatered substrate at shoreline slopes of 1%, 5%, 10% and 20% in a laboratory setting and modelled results using gamma regression models. Model results suggest both movement distance and movement rate increased with increasing slope and increasing larval length. We used the models to predict minimum distances and rates that 90%, 75% and 50% of medium‐sized (75 mm) lampreys would move over dewatered substrates on slopes of 1%–20%. The models predicted that 50% of larvae could move distances of ≥31 cm at rates of ≥0.7 mm/s on a 1% slope and distances of ≥502 cm at rates of ≥8.6 mm/s on a 20% slope. We present an example scenario of how information on larval movement capabilities and shoreline slope could guide phased dewatering events to limit impacts to lampreys.

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Bringing partners together: A symposium on native lampreys and the Pacific Lamprey Conservation Initiative

Liedtke,

Harris,

Wang

et al. 2023

N American J Fish Manag

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Salvage using electrofishing methods caused minimal mortality of burrowed and emerged larval lampreys in dewatered habitats

Cited by 3 publications

References 36 publications

Synthesis of larval lamprey responses to dewatering: State of the science, critical uncertainties, and management implications

Synthesis of larval lamprey responses to dewatering: State of the science, critical uncertainties, and management implications

Shoreline slope influences movements of larval lampreys over dewatered substrate

Bringing partners together: A symposium on native lampreys and the Pacific Lamprey Conservation Initiative

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