Greetings,

Statement of the obvious time - adult Sturgeon migrate upriver with fresh rains. Between noon Friday 3/4 and 10AM today (Tuesday 3/8), droves of tagged Sturgeon have appeared on our real-time array. Four Green Sturgeon and 16-17 White Sturgeon were detected by our real-time network of 69 kHz VEMCO receivers. One of the Green Sturgeon warrants extended discussion and will be discussed first.

One of the Green Sturgeon detected, last heard at the Tower Bridge last Thursday (3/3), is of potential management concern. This Green Sturgeon was heard at Feather River Friday afternoon (3/4) and Knights Landing Saturday (3/5) followed by a single detection yesterday (3/7) at Tisdale Weir at 6:25 AM. This is of concern because the river stage is now over-topping Tisdale Weir, and flows over the Weir were reported as of 8 AM PST yesterday according to data on water.weather.gov. Although our real-time receiver is upstream of the Weir on the main-stem of the Sacramento River and Green Sturgeon should be swimming significantly lower in the water column than the crest of the river, the putative arrival of the fish by Tisdale Weir within 100 minutes of the first reported over-topping indicates a small, but existing, possibility of stranding/entrainment in the Tisdale and Yolo Bypass.

Of the other three detected Green Sturgeon, one was detected and reported on last week and the other two had their first detections of 2016 since the last report. The Green Sturgeon last seen 3/4 at Tisdale Weir has since been heard Saturday 3/5 at Colusa, clearing the area before the Weir over-topped. Of the two new Green Sturgeon entering the system, we first detected them both at the Capital City Freeway bridge, followed by the Tower Bridge (Saturday 3/5 and Monday 3/7). "Saturday's fish" has also been detected 3/6 at Knights Landing, so may be expected to arrive today or tomorrow at Tisdale. The Sacramento River is expected to reach its maximum height (for a few days at least) at Tisdale at approximately 6PM today, after which the river is predicted to fall below over-topping level Thursday.

In the realm of White Sturgeon detections, nine of the detected tags are assigned to White Sturgeon not detected previously in 2016. The remaining 7-8 fish were detected previously in 2016, although four of these had not been detected for over one month. Thirteen of the White Sturgeon were detected only at Lisbon Weir within the Yolo Bypass, including 8 of the 9 newly detected fish and all four of the unseen-for-over-a-month cohort. Of those heard over a month ago, three of the four were previously last heard at Hood in the main-stem Sacramento River (and the other was at Lisbon Weir). The only newly detected fish not detected at Lisbon Weir was one that was detected earlier today at the Capital City Freeway (CCF) and Tower Bridges. Of the remaining 2-3 White Sturgeon previously detected and not currently at Lisbon Weir, 1-2 were detected where they were last seen at Colusa (one of two fish is represented by a single detection this week, so may have been a false-positive detection). The last remaining tagged White Sturgeon, previously heard 2/24 at Tower Bridge, was heard Saturday 3/5 at the Feather River inflow.

Although I've attempted to convey the information descriptively, please let me know if you would prefer to receive a tabular representation of these updates (either in lieu of or as a supplement to the written version). If there is overwhelming interest, I can scrap the current format in favor of a data-driven format. Immediately below my e-mail signature of this report, you'll find the tabular representation of the current and previous reports.

--Matt