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33 To evaluate the accuracy of the shocking-seining method, a short side channel was first sampled in the usual manner and then rotononed. The results showed that the shocking-seining method was yielding a fairly reliable estimate of relative abundance (Table 3). The exceptions were larger species such as carp, black bullheads and channel catfish which were captured using rotenone but not with the shocking-seining method. This was further evidence that larger fish were generally able to avoid capture by the shocking-seining method. Threatened and Endangered Endemic Fish Colorado Squawfish (Ptychocheilus lucius) The squawfish was originally found throughout the entire Colorado River basin, but its distribution has been greatly reduced by man's alterations of the system. It has essentially been eliminated from the Colorado River below Lake Powell and from the Green River above the mouth of the Yampa River (Minckley, 1973; Vanicek et al., 1970). Relatively large numbers of squaw- fish have been repeatedly found in the Yampa River (Holden and Stalnaker, 1975a, 1975b; McAda and Seethaler, 1975; Seethaler, 1978; Prewitt et al., 1978). In southern Utah it is restricted to the Green and Colorado Rivers. Holden and Stalnaker (1975a) considered it rare in collections made in the Green River in Desolation Canyon and in the Green and Colorado Rivers in Canyonlands National Park. The life history and ecology of the squawfish has recently been reviewed (Seethaler, 1978). Six adult squawfish were captured in the lower 12.2 mi (19.6 km) of the White River. Three were collected on July 11, 1978 and three on September 28, 1978 while electrofishing from a boat (Figure 19). At least seven other squawfish were "observed" in this section of the river (Figure 19). Observed fish were those identified from the electrofishing boat by a qualified individual (Delmar Robinson, U. S. Fish and Wildlife Service, member of the