Introduction & Objectives

The southern distinct population segment (DPS) of the green sturgeon is listed as threatened under the Endangered Species Act.  The green sturgeon’s occurrence and habitat use is not well known.  Therefore it is currently unknown if the green sturgeon occurs and uses areas where the Navy conducts training and testing activities.  Over the past 15 years, hundreds of green sturgeon have been tagged with acoustic pinger tags which may have been detected by receivers deployed in the Puget Sound area.  The objectives of this project are to compile and review existing databases of green sturgeon acoustic tag detections in Puget Sound and the Straits of Juan de Fuca, analyze the data for distribution and seasonality of distribution, and identify any key physical nearshore habitat and water quality conditions that might explain the distribution. 

Technical Approach

Data was compiled from green sturgeon acoustic tag deployments and acoustic receiver deployments from west coast databases and scientists.

In 2002, NOAA Fisheries began tagging green sturgeon in collaboration with other agencies. All green sturgeon transmitter codes from this work were available for this study, along with their associated metadata (e.g., length, sex, DPS).  A number of other agencies have tagged additional green sturgeon that could occur in Puget Sound. To ensure that all detections of acoustically tagged sturgeon were included in our collection, two existing databases that collate acoustic detections in the region were searched:  the Ocean Tracking Network and the Hydra database. Other sturgeon researchers from Canada to California collaborated on this effort to ensure that the working list of unique green sturgeon tag codes was as complete as possible.   

Progress & Results

Acoustic detection data indicated that green sturgeon from both the northern and southern DPSs can occur in Puget Sound and at Admiralty Inlet, but at low rates relative to their presence in the Strait of Juan de Fuca.  Our results support the decision by NOAA Fisheries to designate the Strait of Juan de Fuca as an area of high conservation value for southern DPS green sturgeon.  These results also confirm earlier findings that Puget Sound is of lower conservation value to southern DPS green sturgeon, based on the lower rate of detections in this area.