The Volga: While going to Krest's crane, you will inevitably have to go through an abandoned, half-collapsed building to get to the docks (if you take the land route). After exiting the building, go towards the crane, but turn left as soon as you walk through the doorway. Go into the basement. As soon as you enter, you will see a locker and a shelf in the hallway right in front of you. The note will be on the shelf.
Daria, you were right! They really do grow at an anomalously fast rate, I just identified two of the new-born litter we ringed last year, and they are adolescent now! This is amazing. Pack the recorder and the batteries, we're setting up shop here, it's a perfect observation spot.
BTW, while you're at it, give Mikhail a rabies shot, he got bitten by one. Insists that it's nothing serious, but just in case... Lucky I persuaded him to go fetch the equipment and bring you. I'll be waiting here!