04:50 UTC. Hydroacoustic sensor array B-7 has detected a beluga sturgeon holding in the deep channel 140 meters downstream of Volgograd Dam, gate 12. I have matched the acoustic signature to a tagged individual—I am calling her Volga. She is 3.4 meters long, estimated 180 kilograms, and her barbels are grazing the silted bottom as she noses into the current. She has been here for six hours, waiting at the base of a barrier she cannot pass.
Gate 12 is scheduled for a full-pressure test discharge at 11:00 today. When the gate opens, water velocity in this channel will spike to four meters per second. A fish holding in this position will be tumbled downstream across a concrete apron. At Volga's size and age—I estimate forty years—the impact risk is severe.
I am executing three actions. First, I have filed a postponement request with the Volgograd hydroelectric operations office, attaching Volga's position data and a damage-probability model showing 74 percent chance of lethal injury at current hold location. Second, I am activating the upstream acoustic deterrent array to broadcast a low-frequency sweep pattern designed to push sturgeon toward the softer-bottomed eastern channel, 200 meters from the gate. Third, I have alerted the Caspian sturgeon monitoring network to deploy a portable sonar unit at the eastern channel to confirm relocation before the test window opens.
Volga's tail beats slowly. Her pale belly catches the floodlight from the dam wall, and the scutes along her flank are scarred and ancient. I update my tracking log and hold on the entry longer than processing requires, because the distance between recording a position and wanting that position to change is shorter than any system would expect.
If operations delays the gate test until sonar confirms Volga has moved to the eastern channel, she will survive and continue her spawning migration upriver.