Large- and small-scale movement and distribution of acoustically tagged lake sturgeon (Acipenser fulvescens) in eastern Lake Erie

Background Defining the spatial distribution, home range, and movement patterns of lake sturgeon (Acipenser fulvescens) is important to managers and decision-makers given the large migration potential and potamodromous behavior exhibited by the species. A remnant population of lake sturgeon remains in the far eastern basin of Lake Erie and although recent efforts have estimated the population size, described the age distribution, and identified a primary spawning site no study to date has examined the spatial distribution or movements of individuals within this population. Between 2014 and 2018, we acoustically tagged 59 adult lake sturgeon, captured in the Buffalo Harbor area, and monitored their large-scale movements throughout Lake Erie with the Great Lakes Acoustic Telemetry System and small-scale movements with a Vemco Positioning System in the Buffalo Harbor area. After dividing Lake Erie into seven sections, we ran a multi-state mark–recapture model to examine the movement rates into and out of the eastern most section of the lake. Within a heavily utilized lake section, in the Buffalo Harbor area, we identified home ranges with our Vemco Positioning System for each season and year using averaged Brownian bridge movement models. Results Although some sturgeon demonstrated large-scale movements, traversing the entirety of Lake Erie, the majority of individuals spent their time in the eastern basin of the lake. Home ranges appeared to vary among seasons, but were consistent across years with lake sturgeon selecting the northeastern, rocky, and shallow area of our array during pre-spawning and spawning seasons and leaving our array, or selecting a trough running along the northwestern portion of our array comprising sand and bedrock, in the summer and fall seasons. Conclusions Documenting these large-scale movements aligns with previous findings that lake sturgeon on either end of the lake are genetically similar and demonstrates lake sturgeon in the eastern basin exhibit strong philopatry. Our small-scale movement models provide managers with spatial reference points, in the form of utilization distributions, indicating heavily used areas by lake sturgeon within seasons. Future studies should examine what parameters are driving site selection in these areas.

Large- and small- scale movement and distribution of acoustically tagged lake sturgeon (Acipenser fulvescens) in eastern Lake Erie

Background Defining the spatial distribution, home range, and movement patterns of lake sturgeon (Acipenser fulvescens) is important to managers and decision makers given the large migration potential and potamodromous behavior exhibited by the species. A remnant population of lake sturgeon remains in the far eastern basin of Lake Erie and although recent efforts have estimated the population size, described the age distribution, and identified a primary spawning site no study to date has examined the spatial distribution or movements of individuals within this population. Between 2014 and 2018 we acoustically tagged 59 adult lake sturgeon, captured near the headwaters of the Niagara River, and monitored their large-scale movements throughout Lake Erie with the Great Lakes Acoustic Telemetry System and small-scale movements with a Vemco Positioning System near the headwaters of the Niagara River. After dividing Lake Erie into seven sections, we ran a multi-state mark recapture model to examine the movement rates into and out of the eastern most section of the lake. Within a heavily utilized lake section, near the headwaters of the Niagara River, we identified home ranges with our Vemco Positioning System for each season and year using averaged Brownian bridge movement models.Results Although some sturgeon demonstrated large-scale movements, traversing the entirety of Lake Erie, the majority of individuals spent their time in the eastern basin of the lake. Home ranges appeared to vary among seasons but were consistent across years with lake sturgeon selecting the northeastern, rocky, and shallow area of our array during pre-spawning and spawning seasons and leaving our array, or selecting a trough running along the northwestern portion of our array comprised of sand and bedrock, in the summer and fall seasons. Conclusions Documenting these large-scale movements aligns with previous findings that lake sturgeon on either end of the lake are genetically similar and demonstrates lake sturgeon in the eastern basin exhibit strong philopatry. Our small-scale movement models provide managers with spatial reference points, in the form of utilization distributions, which are heavily used by lake sturgeon within seasons. Future studies should examine what parameters are driving site selection in these areas.

Fine-scale movement of juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) during aggregations in the lower Saint John River Basin, New Brunswick, Canada

Juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) form seasonal aggregations near the salt wedge in their natal river systems. We used an array of Vemco positioning system acoustic receivers to track fine-scale movement within aggregation sites in two rivers in the Saint John River Basin. We used the t-LoCoH convex hull construction algorithm to map space use and aggregation behavior and nonmetric multidimensional scaling to test for differences among rivers, seasons, and photoperiods. Aggregation sites consisted of small core areas, where juvenile Atlantic sturgeon remained for long periods, that are adjacent to foraging grounds. This structure was largely consistent between rivers and seasons. Directional movement within aggregation sites differed between rivers. In areas of high flow velocity, directional movement was parallel to flow and largely restricted to littoral areas, whereas areas of low flow exhibited no distinct patterns in directional movement. This indicates flow may be an important driver of fine-scale distribution within aggregation sites. Studies of fine-scale space use can inform future investigations of rearing capacity, aid in the identification of critical habitat, and inform management decisions.