Former CDFW employee here,
So sturgeon monitoring in the estuary has gone through a lot of changes the last couple years (including the entire large fish program being DISCONTINUED as of 2023
https://iep.ca.gov/Science-Synthesis-Service/Monitoring-Programs/Sturgeon). The biggest problem as far as sturgeon monitoring goes was finding a consistent sampling method that could survey both adults and juveniles, so for many years they did not have a robust population estimate. In the last few years of the sturgeon survey, they made some significant changes that mirrored successful studies further north, which is what led to the new lower estimate (Science takes a long time, when I left, my project was also about a year behind on data processing) Other projects that sample the estuary (but not for sturgeon) have also noticed a really precipitous decline in both species of sturgeon, but these projects also never really caught enough consistently to say anything about that data.
Now as for the discontinuation of the sturgeon survey, it really sucks, and just about everyone in that program (and the office) was deeply disappointed. I can't speak to the reasons why it was discontinued (and even if I knew, I wouldn't be authorized to share), but my guess is shifts in research priority to "certain" endangered species (you all know the one), the water politics involved in researching *that* species, and general budget constraints (CDFW has had a very BAD couple years). Unfortunately, such is the state of estuary science in California—a lot of projects are being stripped to the bone, while new ones are haphazardly assembled from the scraps to try to fill in the gaps.
