Rangersedge,
I think the members that have grass shrimp populations that survive long term in their ponds frequently have some type of heavy plant cover in the shallow water edges to provide a safe haven.
You might want to search some grass shrimp threads to see if your pond has the necessary ingredients for success. Otherwise, they are just an expensive snack!
(I am not any type of grass shrimp expert, just going off of fuzzy memories from reading PB.)
