7025 - Laserfiche WebLink

Home Browse Search

18 Management recommendations Management recommendations from the literature included suggestions for flow maintenance or regulation, habitat enhancement, preservation of natural habitats and reaches, stocking endangered fish large enough to avoid predation, and protocols for stocking and control of nonnative gamefish. Several recommendations in the literature warned of altering flow regimes that native fishes coevolved with while other recommendations suggested that flow regimes could be regulated to the advantage of native fishes and a disadvantage of nonnative fishes. Karp and Tyus (1990b) warned that alterations of natural flows in the Yampa River might enhance the further proliferation of nonnative species. They suggested protecting natural flows of the Yampa River. Osmundson (1987) suggested that upstream dams on the Colorado and Gunnison rivers, Colorado, should be discouraged from moderating natural spring flooding that may be useful in controlling nonnative fishes. Osmundson and Kaeding (1989a) suggested that "flows might be controlled to increase temperature and promote spawning earlier in the year" which might improve growth and survival of larval squawfish. High flushing flows during spring may be the only means to control introduced species (Osmundson and Kaeding 1989a; 1991). Osmundson and Kaeding (1991) recommended peak spring flows for the 15-mile (24 kIn) reach of the upper Colorado River, Colorado, that they hoped would decrease introduced fishes. Higher flows were suggested based on the negative relationship between peak flow and nonnative abundance and the positive relationship between peak flow and native abundance. Grabowski and Hiebert 1989) warned that increased water levels might increase shoreline habitat for young native fish, but might also provide habitat for larger predatory introduced fish in backwaters. Valdez (1990) believed that management of flows would only temporarily decrease densities of many nonnatives because of their high reproductive potential. Minckley and Meffe (1987) suggested that regular flood events might decrease nonnatives and allow natives a chance to recover from predation or competition, allowing the two faunas to coexist Regular floods would shift the advantage to native fishes that could probably survive this type of event better than most nonnatives. Although they were directing this action toward small streams the applicability for larger rivers and spring run-off flooding remains to be shown. Several predatory centrarchids and ictalurids have been reduced or eliminated by flooding in Arizona streams while natives were little affected However some extreme flood events may decrease or even decimate native populations and drastically alter habitat by bank cutting (Meffe 1984). Habitat enhancement has was also recommended as a method to enhance native fish populations, but any habitat modification must account for the affects on nonnative fishes. Behnke (1980) suggested the creation of backwaters for mitigation of development. The backwaters would serve as nursery grounds of rare fishes and control structures could be installed to exclude nonnative predators and competitors. Johnson (1980) warned that these