Career opportunities exist for parasitologists who can assist wildlife managers in the development of programs designed to protect animals in their natural environment. Parasitologists working for government agencies, industry, and universities survey wild animals for parasites and disease and develop strategies to reduce the negative impact of parasites on wildlife populations. Conservation biologists are especially interested in parasitic diseases of threatened and endangered species and use this information to formulate management plans for their protection. Monitoring parasites in wild animals that are capable of being transmitted to man is another important function of parasitologists. Fisheries biologists not only need information on the role of parasites in causing fish disease and fish parasites that humans can acquire from eating fish, but may use parasite data to understand aspects of the .. of natural populations of fishes. For example, parasites have been employed as "biological tags" and a knowledge of a fish's parasites may provide useful information regarding the geographic origin of a stock of fish or insight into the migratory patterns of fish in aquatic ecosystems. Knowledge of parasite life cycles may provide wildlife biologists with data on trophic interactions and food webs. Information on parasites is important to managers who wish to relocate game species to new geographic regions. Alterations of natural environments such as damming of rivers, channelization of streams, cutting of timber may affect important game species by altering parasite abundance, and the advice of parasitologists is often sought before making such decisions.