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Biology subjects

Balazik, M.

Publications and source records attributed to Balazik, M..

2 recordsLinked to original sources

Spawning Drivers of Female Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) in the James River: A Fine-Scale Temporal Analysis

Fall-run Atlantic Sturgeon occupy riverine habitat for extensive periods of up to several months during periods of spawning. It is generally not feasible to eliminate potential anthropogenic stressors during the entire time Atlantic Sturgeon are on spawning habitat. If data were available to accurately predict when eggs and larvae are in the water column, potential impacts could be minimized for this relatively short timeframe, compared to the entire season of freshwater residency by adults. This research used acoustic telemetry data for adult female sturgeon, along with water temperature and discharge, to predict when females were likely releasing eggs versus merely staging in spawning habitat waiting to spawn. The descriptive and Bayesian model results predict that egg release is associated with water temperatures ranging from 20-26{degrees}C and pulses in river discharge, often confining egg release to a few days or weeks. By using weather data that predict relatively short periods of when egg release occurs versus longer periods that includes staging, resource managers can more feasibly collaborate with water usage groups to ameliorate egg/larvae survival.

animal behavior and cognition↗

Juvenile Atlantic sturgeon survival and movement in proximity to an active cutterhead suction dredge

During 2019 and 2020, 268 (30-71cm fork length) juvenile Atlantic Sturgeon were captured and released in proximity to an active cutterhead suction dredge among three sites in the James River, Virginia. Of these captures, 30 were implanted with acoustic tags and telemetry was used to track their movements. Three juveniles telemetry tagged prior to this project were also detected moving within dredge operations. Cumulatively, tagged juveniles made at least 125 passes of the dredging operations with no evidence of detrimental impact in terms of survival and all were detected following the cessation of dredging. Juveniles were captured, presumed feeding, around 100m from the dredge in areas that could easily be avoided if the dredge created a stressful environment. No significant differences in catch-per-unit-effort were found when trawl catch was compared to a reference location or when monitoring gill netting catch 100m down current of a dredge over a month-long period at one of the sites. These results suggest a finding of very low risk of entrainment, migratory blockage or avoidance within 100m of an active cutterhead suction dredge by juvenile Atlantic Sturgeon.

animal behavior and cognition↗