Larval drift characteristics, habitat use, and environmental determinants of year-class strength in wild age-0 Lake Sturgeon, Acipenser fulvescens, within a large impounded river

Abstract

The dynamics of early life stages of Lake Sturgeon ( Acipenser fulvescens) within a large impounded river were studied. Recruitment success, larval drift, and basic habitat and diet use were observed and analysed over a two-year period. As part of a separate study, larval drift monitoring, and juvenile gillnetting were conducted one year prior to the start of the current study; these results were considered preliminary work and included in the analyses. Timing, duration, and extent of larval drift varied from year to year. No correlation was found between year-class strength and water discharge or temperature. Post-drift, age-0 Lake Sturgeon were found in habitats consisting of sand substrates, in depths of greater than 6 m (maximum 24 m), and low to medium velocities (0.0- 0.4 m s-1 ). Diet was composed of Diptera, Ephemeroptera, Trichoptera and Nematoda. Age-0 Lake Sturgeon captured in Dorothy Lake only consumed Dipteran organisms. Nitrogen isotopes indicated that age-0 Lake Sturgeon captured in this lake were significantly different from those captured in other locations of the study area. Daily growth was calculated as 2.0 mm in total length and 0.20 g in weight from August through September. Findings from this study will aid in future age-0 Lake Sturgeon research and management including artificial propagation and nursery habitat remediation.