The papers resulting from this symposium review the ecological and genetic effects of fish introductions throughout the world. Purposeful introductions rarely have achieved their objectives. Moreover, both intentional and unintentional introductions usually have been harmful to native fishes and other taxa through predation, competition, hybridization, and the introduction of diseases. We must learn from the past in order to avoid mistakes in the future. Introductions should not be used as a management tool without sufficient prior information and understanding to predict their effects.
Introductions are often made or permitted because of the demands of certain interest groups (e.g. anglers or aquaculturists). Education of the public to the potential dangers and costs of such introductions is essential. Cooperation among management agencies is necessary to regulate and control both the purposeful and accidental introductions of fishes.
Waples (1991) reviews the history of genetic interactions between hatchery and wild salmonids in the Pacific Northwest of the United States. He concludes that supplementation programs have not been successful and that such programs present a threat to the long term survival of Pacific salmon species. He suggests that the rule of (hatchery) supplementation programs should be first, do no harm. That is, such programs should not be undertaken unless there is adequate assurance that wild stocks will not be harmed. He also recommends that monitoring programs should be an integral part of any supplementation effort.