Laserfiche WebLink
1 <br /> <br /> <br /> <br />usually flourish in impoundments and may subsequently invade riverine habitat up- and <br />downstream of reservoirs (Martinez et a1. 1994). Also, several non-native fishes <br />including red shiner Cyprinella lutrensis, northern pike Esox Lucius, and channel catfish <br />Ictalurus punctatus are adapted to lotic conditions. <br />Negative effects ofnon-native fishes include predation (Tyus and Beard 1990, Ruppert et <br />al. 1993, Tyus and Nikirk 1990, Nester 1995, Douglas and Marsh 1998), competition and <br />1 <br /> <br /> <br /> <br />1 <br />ii <br /> <br />1 <br /> <br />1 <br /> <br /> <br />r <br />trophic interactions (Lamarra 1999, Osmundson 1999), and non-native fish pathogens <br />(Robinson et al. 1998b, Heckmann et al. 1993). Exotic plants such as salt cedar Tamarix <br />chinensis and Russian olive Elaeagnus angustifolia are also implicated in the demise of <br />native CRB fishes because of their effects on fish habitat {Carlson and Muth 19$9, <br />Bestgen 1990). The cumulative effects of dams and diversion structures, introductions of <br />non-native fishes and pathogens, intentional poisoning, environmental contamination, <br />groundwater pumping, introductions of non-native plants, and agricultural and urban <br />development on the native fishes of the CRB are well-descried by numerous summary <br />articles (Miller 1946, Miller 1961, Hinckley and Deacon 1968, Rinne and Hinckley <br />1991; see also Table 3). <br />Human alterations to the GRB have contributed to extinction of the I,as Vegas dace <br />Rhinichthys deaconi and Pahranagat spinedace Lepidomeda altiveiis, and an additional <br />18 species are extremely rare (Carlson and Muth 1989). Of the eight big-river skies <br />once found in the CRB, Colorado pikeminnow, bonytail, humpback chub, and razorback <br />sucker are rare and federally listed as endangered. The other four big-river species <br />(roundtail chub, flannelmouth sucker, bluehead sucker, and speckled dace) occupy a <br />greater proportion of historical habitat than the endangered fishes, but are also declining <br />>n many areas. <br />Final Report September 2002 <br />u <br />