A close-up of a green sturgeon being held.

Photo Credit: Oregon Department of Fish and Wildlife. Green Sturgeon. 2023. https://myodfw.com/fishing/species/green-sturgeon

Results

From these data, a total of 864 sturgeon carcasses, including at least 195 white sturgeon and 17 green sturgeon, were identified. These numbers represent minimums.
What killed the fish was likely a combination of the toxicity of the algae, Heterosigma akashiwo, and the lower dissolved oxygen levels.
Graphics to represent the progression of the bloom and the spatial distribution of the carcasses were made.

Spatial Distribution of Carcasses by Data Source

Figure 1: Reports for HABs-related sturgeon carcass sightings were split between many different agencies, personnel, and surveys. After vetting each report for duplicate sightings and mortalities not caused by the HABs event, the compilation of each report has been aggregated in this map. As part of the CDFW Sturgeon Trammel Net Survey, we conducted an open-water survey for sturgeon carcasses related to the HABs event (CDFW_OpenWater).

Spatial distribution map that shows carcasses sightings and who reported them. The carcass sighting location is shown with a dot on the map while the source of the report is denoted by the color. These sources included Baykeeper, CDFW Shore and Open Water survey, iNaturalist, CDFW HAB coordinator Jenna Rinde, SFEI, USGS, the Sturgeon Research Program's mortality study, and the Wildlife Health Laboratory.

Spread of H. akashiwo vs. Reports of Sturgeon Carcasses

A graph showing the amount of sturgeon carcass reports on each date. A bar graph shows the number of reports divided by species (either white sturgeon, green sturgeon, or sturgeon spp.) A red line shows the accumulative number of reports.

Figure 2: Satellite imagery of the spread of H. akashiwo compared to the sturgeon carcass reports. Notice the delay between the peak severity of the algal bloom and the peak reporting of carcasses.