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<br />11 <br /> <br />These predictive equations differ fr~m previous equations presented in <br />Haynes et ale (1983, 1984) due to reinterpretation of Hamman's (1981) data <br />and, in general, resulted in a narrowing of previous ranges of estimated <br />spawning dates. The usefulness and accuracy of these equations were <br />discussed in Haynes and Muth (1984). <br /> <br />RESULTS <br /> <br />General <br /> <br />Colorado River Study Area <br /> <br />A total of 1,105 seine and dip net samples were taken in the Colorado <br />River during 1979-1983 (Table 1). Twenty fish species were collected during <br />1981-1983, mostly within the families Cyprinidae and Catostomidae (Table 2). <br />For those years, non-native species predominated, constituting 90%, 82%, and <br />60% of the total catch, respectively. Red shiner (Notropis lutrensis), sand <br />shiner (~. stramineus), and fathead minnow (Pimephales promelas) were the <br />most abundant non-native species and accounted for 79% of all specimens <br />collected during 1981-1983. Mosquitofish (Gambusia affinis), which were <br />uncommon in 1981 and 1982 collections, were more abundant in 1983 and <br />accounted for 18% of all fish sampled. Notably, 11 redside shiner <br />(Richardsonius balteatus) were collected between river km 230.4 and 243.4 on <br />2 May 1981, representing a new distributional record for this species (Haynes <br />et ale 1982). Speckled dace (Rhinichthys osculus), bluehead sucker <br />(Catostomus discobolus), and Gila spp. were the most abundant native species <br />collected, together constituting 16% of the total combined catch for <br />1981-1983. <br /> <br />Table 1. Total number of samples taken in the <br />Colorado, Yampa, and Green rivers, <br />Colorado, 1979-1984. Numbers are <br />combined seine and dip-net samples. <br />Parentheses denote number of drift- <br />net samples taken. <br /> <br />Year Colorado <br />1979 155 <br />1980 114 <br />1981 295 <br />1982 336(48) <br />1983 205 <br />1984 <br />Total 1,105(48) <br /> <br />River <br />Yampa <br /> <br />Green <br /> <br />215 <br />423 <br />295(13) <br />245(252) <br />148(168) <br /> <br />1,326(443) <br /> <br />(155) <br />(155) <br />