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

Abstract

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.