Managing Southwestern Native and Nonnative Fishes: Can We Mix Oil and Water and Expect a Favorable Solution?
John N. Rinne, Larry Riley, Rob Bettaso, Roger Sorenson, and Kirk Young
Abstract.—The native fish fauna of the Southwest has become markedly reduced in range and numbers over the past century. Dramatic changes in aquatic habitats and the introduction of nonnative fishes are related to their demise. Major southwestern river systems such as the Colorado, Rio Grande, Gila, and Verde presently contain nonnative, primarily sport fish assemblages, in combination with rare, declining, and listed native species. The Arizona Game and Fish Department in collaboration with federal and private agencies is responsible for managing both of these fish groups in a representative state, Arizona. Two questions can be offered: “Is it desirable, and possible, to sustain both fish groups in the waters of Arizona?” and further, “Is it possible to sustain both fish groups in the same river, stream, lake for spring?”
Currently, the Arizona Game and Fish Department (Department) propagates primarily coldwater species; however, a half a dozen species, including the threatened Apache trout Oncorhynchus gilae apache, Colorado pikeminnow Ptychocheilus lucius, razorback sucker Xyrauchen texanus, Gila topminnow Poeciliopsis occidentalis, and desert pupfish Cyprinodon nevadensis, are also reared in hatcheries and refugia habitats. Repatriation programs for these same species are ongoing in Arizona. A critical component for recovery of these rare, native species will be to sustain secure habitats for their repatriation. Cooperative programs with the U.S. Forest Service, U.S. Bureau of Land Management, and U.S. Bureau of Reclamation seek available habitats for restoration of native fishes. The management activities of many agencies over the last century have contributed to the hydrological and biological state of southwestern river systems. Cooperation among these same agencies will be necessary to conserve and enhance native fishes while sportfishing continues. The answer to the above two questions are (1) “Yes, both groups are being managed under department mission statements”; and (2) “No, efforts to do so should in the same habitats are not recommended and should not be attempted.”