Use of a multi-sensored AUV to telemeter tagged Atlantic sturgeon and map their spawning habitat in the Hudson River, USA

An autonomous underwater vehicle (AUV) equipped with a telemetry hydrophone was used to observe Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in their Hudson River spawning habitat. The positions of two transmitter-tagged fish were repeatedly determined using two methods; probability plots derived from 2-dimensional matrices of received transmitter signal strength calibrated by a reference tag, and by synthetic aperture calculations. Targets thought to be additional, untagged, Atlantic sturgeon were located from sidescan echograms. Positions of tagged and untagged fish were mapped to benthic and hydrographic habitat features by matching the fish´s location with the vehicles time and spaced-referenced sensor data. Results were compared to those of surface vessel-based mobile telemetry solutions using bearing and signal strength. This case study demonstrated the usefulness of AUVs to fish telemetry in challenging conditions. The rapid survey provided focus and scaling to further efforts at understanding essential habitat for this Red Listed species.