Any tips or pointers on anchoring bedding or supporting traps on rock bottom streams Beaver otter mink etc

Gotta a few like this where I trap...had to bring in heavy weights for anchors...ie, brake rotors, concrete blocks, old weights and cable my traps off to them when using footholds or snares.
Bodygrippers can be positioned on the banks and anchored off there but check your state laws first. There are several trap modification guys that make different trap stabilizers for these situations...gotta get creative.
Good luck.

When trapping at reservoir (dam) faces, bridges or the plunge pools of the outlets of culverts or any where it was rocky for me I started out using pre-made H.D, 1" chicken wire baskets and 14 ga wire to close them and connect to trap chain. Later switched to woven poly seed bags and wired them up. Fill, twist, and set. Did not use a shovel or sand as some guys need in their areas. Your weight, rocks, were always at the trap site so I just carried the container(s) and filled right there. Sometimes the manmade sites had too large of rip rap and I had to look more but usually found a single rock small enough to fit what I needed. Used them on 1 way slide drowners (both ends) and never lost critter. Limited use on dryland but it held the 1-2 years I used it on them. My Experience. ........................ the mike

For anchoring, bricks work well for bottom edge mink sets, as do windows weights, brake rotors, and railroad plates

Are tou trapping with drowning sets? Size traps? How deep is the water?