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<br /> Table 3.7. Six-year review (10/91 to 10/97) of fishery biologists' San Juan River C. <br />CJ /atipinnis and C. discobo/us abnormality data (Source: Landye et al. 2000). <br />c-' <br />..... <br />c....,., <br />,,:> <br />,-".~ 10/91 1,606 2,6 54 <br />" <br /> 6/92 3,018 3,6 65 <br /> 10/92 3,413 0,3 30 <br /> 10/93 2,959 0.4 55 <br /> 5/94 1,878 3,0 74 <br /> 10/94 9,524 0,6 30 <br /> 5/95 1,266 0,1 25 <br /> 10/95 2,261 0.8 25 <br /> 5/96 2,557 3.4 72 <br /> 10/96 2,888 1,6 33 <br /> 5/97 5,270 0.4 19 <br /> 10/97 7,440 0.3 32 <br /> <br /> <br />flannehuouth sucker collected and that spikes in the number of abnormalities occurred in October 199 I, <br />June 1992, May 1994, and May 1996, During these times, the incidence ofIesions also increased (Table <br />3.7). A regression of percent abnormalities against year using the data from Table 3.7 showed that there <br />was no significant relationship for spring (p<0.3 14) or fall (P<O,442) samples, suggesting that abnormalities <br />neither increased nor decreased during the 7-year research period. The abnormalities tended to be highest <br />in the riverreach from RM 121.0 to RM 156.0, the area from about Four Comers to Hogback Diversion, <br /> <br />Flannehuouth sucker and channel catfish had the most abnormalities (Landye et al, 2000). No Colorado <br />pikeminnow or razorback sucker with major abnormalities were found, although some Colorado <br />pikeminnow had a few external parasites. Landye et al. (2000) concluded that for the San Juan River <br />"abnormality incidence in all fish species is low with the exception of 'spikes' ofIesions and other disease <br />signs during the spring hydrograph." <br /> <br />The fish health data, which were difficult to compare with other rivers because the intensity of study on <br />the San Juan River was much greater than the intensity of most other fishery studies, did not indicate <br />that Colorado pikeminnow or razorback sucker were limited by health issues, Even flannehuouth <br />sucker, the most affected species, typically had 5% or less of the population showing abnormalities. <br />Landye et al. (2000), along with experts from the National Fish Health Laboratory, hypothesized that the <br />lesions seen on flannehuouth sucker may have been caused by interactions with contaminants. <br />It was possible that low-flow periods added to the intensity of contaminant interaction, causing <br />outbreaks as observed in May 1996, In hypothesizing reasons for a general <br /> <br />September 2000 <br /> <br />3-53 <br /> <br />Program Evaluation Report <br />