Damming and burrowing activities of beavers, muskrats and nutria may cause physical damage to ponds by weakening levees and interfering with control structures. Local conservation agents can recommend legal control measures and possibly assist in trapping and relocating certain animals. Snakes
Although it is difficult to eliminate snakes from most ponds, they can be encouraged to leave the area by removing cover such as brush, rocks and high grass in the immediate vicinity. Snakes which remain or appear later can be destroyed as opportunities permit.
Although turtles rarely prey on fish directly, they can increase to the point where they become a nuisance. In this situation, they can be trapped and destroyed. A number of trap designs have been used successfully. (see Figure 24)
A number of bird species may visit farm ponds but few are serious predators on game fish. If a particular type of bird causes unacceptable losses, frightening techniques are generally recommended. Many birds are protected under state and federal laws, which effectively rule out shooting or poisoning.
Excessive mosquito reproduction can usually be avoided by eliminating rooted vegetation from ponds. If this does not control the problem, it may be necessary to introduce mosquitofish, also called gambusia minnows, from ditches or other established water bodies in the area. Be careful not to introduce any fingerling trash fish when collecting and stocking mosquitofish.