Movement Patterns and Size‐Class Influence Entrainment Susceptibility of Lake Sturgeon in a Small Hydroelectric Reservoir

Abstract

Hydroelectric development is considered a threat to the recovery of Lake Sturgeon Acipenser fulvescens populations, in part because of injury and mortality concerns caused by interaction with hydroelectric facilities. Lake Sturgeon resident in small impoundments may be particularly susceptible to entrainment, depending on movement and habitat usage patterns. Using acoustic telemetry, we monitored coarse-scale movements of 99 juvenile, subadult and adult Lake Sturgeon captured throughout a 10-km-long hydroelectric reservoir. Overall, adults moved over larger ranges than did smaller size-classes. However, all size-classes utilized habitat immediately upstream of hydroelectric facilities, and during the 18-month study period, 27% of subadults tagged in the lowermost section of the reservoir, and 8.7% of adults tagged throughout the reservoir were entrained. Movements of juveniles and subadults were generally restricted to extended sections (2-6 km) of contiguous deepwater habitat (>15 m), and passage through the two shallow river narrows that subdivide the reservoir were rare. Over half of the tagged adults (52%) moved upstream or downstream through one or both river narrows, albeit infrequently. Initial residency influenced entrainment susceptibility for juveniles and subadults but not for adults. Results suggest that Lake Sturgeon resident in small impoundments are susceptible to entrainment. However, the presence of river narrows, which function as natural movement restrictors, may largely preclude susceptibility of juveniles and subadults resident in upstream sections.

Movement and habitat use of juvenile Lake Sturgeon (Acipenser fulvescens, Rafinesque, 1817) in a large hydroelectric reservoir (Nelson River, Canada)

“…Stephens Sturgeon are known to exhibit restricted movement patterns in large riverine systems, attributable to a general unwillingness to pass upstream or downstream through shallow river narrows (both natural and inundated falls and rapids) that occur along the flow axes (Barth et al, 2011 ;McDougall, Blanchfield et al, 2013 ;McDougall, Blanchfield et al, 2014 ); however, no movementrestricting features are evident in the current study area between Gull…”

“…St. Clair (Ontario, Can./Michigan, USA) rivers (Barth et al, 2009(Barth et al, , 2011Boase et al, 2014 ;McDougall, Blanchfield et al, 2013 ) as well as other areas of the Nelson River (McDougall, , thus the finding that juveniles behaved similarly in Stephens Lake was not unexpected. Data collection issues precluded some of the more subtle analyses initially planned (e.g., fine-scale habitat selection ratios in Stephens Lake RTZ).…”

Extrinsic Factors Influencing Somatic Growth of Lake Sturgeon

“…, ; McDougall et al. , , ; Boase et al. ) and because water velocities are influenced by depth, each 50th percentile velocity raster was clipped using a 50th percentile flow scenario bathymetric raster.…”

Translocation as a mitigation tool: Demographic and genetic analysis of a reintroduced lake sturgeon (Acipenser fulvescensRafinesque, 1817) population

“…The parentage analysis included both the juveniles and larvae caught between Wawaitin and Sandy Falls dams and the juveniles caught below the Sandy Falls Dam, to give insight into whether juveniles from the reintroduced population were being entrained through the dam ( n = 128; McDougall, Blanchfield, Peake, & Anderson, ). The genetic probability of identity ( P ID ) and the probability of identity between siblings ( P SIB ) were calculated P ID and P SIB using GenAlEx v.6.5.1 (Peakall & Smouse, , ).…”