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<br />Table 9, Mean lengths of all species at Sevens, Yampa River 1998 to 2003,
<br />
<br />YAMPA RIVER Mean length for all fish collect in cm
<br />SEVENS A B C 0 E
<br />Species 1998 1999 2000 2001 2003
<br />Flannelmouth sucker 45,7,d 46.5,d 45,8,d 43,8,abc 46,0
<br />Bluehead sucker 33,5,cd 33,6,cd 31.3,abd 30.0,abc 30,8
<br />Roundtail chub 39.0 40,O,d 39,2 37,9,b 34,5
<br />White S + hybrids 31,1 35,6 25.4 29,7 19.4
<br />Channel catfish 49.0 44,8 49.4 48,1 49,8
<br />Carp 56,7 53,3 57,5 58,6 31,3
<br />Smallmouth bass 29,6 21,0 8.4 13,6 13.2
<br />Northern pike 37.5 41,1 55,2 64,3 34.5
<br />
<br />The most noticeable change in the size distribution at Sevens was with white sucker
<br />and carp, which had much higher numbers of Age-O and Age-l fish in 2003 than in any of
<br />the prior years (Figures A 1-18 and A-38), The strong presence of younger white sucker and
<br />carp in 2003 indicated improved habitat or reduced predation in 2002 and 2003 than in
<br />earlier years for these species. Age-O and Age-! of native fish species were collected in
<br />2003,
<br />
<br />Ii/v Park
<br />
<br />At Lily Park most species displayed very little variation in composition between
<br />years, 8Iuehead sucker were about seven to eight percent of the catch, Roundtail chub,
<br />Colorado pikeminnow, northern pike and white sucker were very rare in all years. Species
<br />composition was variable between years for tlannelmouth sucker and channel catfish.
<br />Flannelmouth sucker was the most common species in the catch at Lily Park. Their
<br />composition was 48% in 2000, 68% in 2001 and 55% in 2003 (Table 10). Catfish
<br />composition had the highest variability among years with 40% in 2000,18% in 2001 and
<br />28% in 2003 (Table 10).
<br />
<br />Total catch (n), density and biomass for fish over 15 cm were much higher at Lily
<br />Park than at the other Yampa River sites (Table II), Total biomass was about four times
<br />higher than Sevens in the baseline years and six times higher in 2003. Total Lily Park
<br />biomass was about six times higher than Duffy,
<br />
<br />21
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