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<br />Backwater seining in July and August yielded 102,033 fishes and was <br />dominated by non-native red shiner Notroois lutrensis (87%) and fathead <br />minnow Pimeohales oromelas (6%). Native fishes, including Colorado <br />squawfish (3%), comprised only 6% of the catch (Table 1). <br />Backwater seining in September and October yielded 67,179 fishes <br />representing 24 species (Table 1). The most abundant species were the <br />introduced red shiner (65%) and fathead minnow (16%). Native fishes <br />included Colorado squawfish (6%), suckers (3%), speckled dace Rhinichthvs <br />osculus (< 1%) and chubs (< 1%). Colorado squawfish was widespread in <br />distribution and collected in 57% of the backwaters sampled. <br />Most fish collected in seines were adults and young of small fishes, <br />or young of larger fishes. Few large fish were captured, and the average <br />TL of the most common species, red shiner and fathead minnow, was 30-40 <br />mm. Age-O Colorado squawfish averaged 41 mm TL by autumn (Table 1). <br />In addition, other species associations within backwaters were also <br />weak (r < 0.5) but generally positive (r > 0 for 47 of 55 values); all <br />significant correlations were positive (r = 0.08 to 0.51, P < 0.05). <br />Abundance of Colorado squawfish and red shiner, fathead minnow, suckers, <br />channel catfish, and common carp Cvorinus caroio were only weakly <br />correlated (r = 0.03- 0.32; P < 0.05). Thus, there was no evidence that <br />abundance of one species was associated with reduced numbers of another <br />species. <br />The relative abundance (CPUE) of fishes fluctuated between years, <br />and was negatively correlated with maximum spring and mean August / <br />discharges (Table 2). Colorado squawfish and red shiner abundance were <br />correlated with higher flows in both nursery areas (r > -0.7, P < 0.05). <br /> <br />7 <br />