I disagree entirely. It may have nothing to do with forage or food availability and not everything eats crayfish, especially once they get bigger. I've worked on more than 1 pond that is over-run with crayfish and they now have to use trapping programs where the remove 10,000s of crayfish in every effort but most too small to eat.

One problem the crayfish cause is the lack of submerged aquatic plants. If they run out of food they just graze down all the plants and nothing will grow.

Before I stocked crayfish I'd be sure I knew more about that pond.