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2001 after most of a growing season. The presence of largemouth bass 50-74 mm long <br />in late August suggested that reproduction had occurred within the isolated backwater. <br />For green sunfish, only one very small individual (< 40 mm TL) was captured and recent <br />reproduction was otherwise not evident. However, in another backwater that also <br />appeared to have remained isolated during 2001 (Pumpkin-Head backwater; rm 147.4), <br />9% of the green sunfish collected (N = 88) in late summer (August 30) were < 40 mm <br />TL, suggesting an age-0 year class produced on site. <br />Other centrarchids <br />Bluegill, black crappie and smallmouth bass were much less abundant than green <br />sunfish and largemouth bass. Bluegill were commonly found, but not abundant: total <br />catch per season ranged from 2 to 201 (Table 1). Distribution of bluegill was somewhat <br />clumped: 175 were collected from two backwaters near rm 147, or about 28% of the <br />three-year catch (N = 630); 18% of the three-year catch was from Labor Camp <br />backwater (rm 183.3); 13% was from a backwater at rm 162.9, and another 12% from a <br />backwater at the downstream end of Skipper's Island (rm 154.1). Black crappie were <br />rarely found: catch was 1-10 individuals per seasonal effort, totaling 27. Smallmouth <br />bass were also rare: a total of 27 was removed during the three-year effort. These were <br />found in six backwaters scattered throughout the Grand Valley portion of the target <br />reach. Total catch at five of the six backwaters was 1-3 individuals. However, in the <br />sixth backwater (rm 175.6), five smallmouth bass were captured on one occasion and <br />another 11 individuals were captured in June 2000 when the backwater was electrofished <br />as part of another study. These 16 fish represented 59% of the total smallmouth bass <br />removed. Individuals from this backwater were relatively large, ranging from 228 to 374 <br />mm TL (mean = 286 mm long). Two sizable irrigation return canals drain into this <br />backwater and may have been the source of these fish; one of the canals drains directly <br />from a large pond located in the Colorado River Wildlife Area near 30 Road in Clifton, <br />Colorado. <br />16