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WSP06495
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Last modified
1/26/2010 2:23:02 PM
Creation date
10/12/2006 1:40:29 AM
Metadata
Fields
Template:
Water Supply Protection
File Number
8240.300.31.J
Description
San Juan River - Environmental Studies
Basin
San Juan/Dolores
Water Division
7
Date
11/1/1999
Title
San Juan River Fish Health Surveys (1992-1999)
Water Supply Pro - Doc Type
Report/Study
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<br />o <br />c~ <br />N Gross pathology data from inspection fish and field notes of both fish health and fishery biologists <br />I." demonstrated a decreasing abnormality incidence from 1993 to 1999. However, lesions increased in <br />c.:; May 1996 to levels resembling the disturbing May 1994 and June 1992 levels. It is unlikely that these <br />0. spikes oflesions can be attributed solely to spawning stress that occurs annually. <br /> <br />Bacterial isolates of San Juan River fish: Of all the bacterial species isolated from all fish sampled, <br />none are known primary fish pathogens, although Aeromonas hydrophila, the causative agent of Motile <br />Aeromonas Septicemia (MAS), usually presenls itself afIer the fish has been stressed. However, most <br />would be considered opportUnistic or secondary fish pathogens. These taxa would affect fish that have <br />been compromised by lesions, reproductive stress, and predator wounds. Fish canying these bacteria are <br />not an immediate threat to humans in contact with the San Juan River. Given the number ofbaclerial <br />taxa present in the system, and new evidence that species such as Pseudomonas aeruginosa can affect <br />both plants and animals, humans with already compromised health conditions should lake precautions <br />with water contact between Bluff, Utah, and Farmington, New Mexico, where most of these bacteria <br />were recorded. <br /> <br />Electrofishing damage: Possible electrofishing damage was noted by observation of spinal deformities <br />in fishery biologists data and damaged kidney tissue during fish health surveys. The radiographs of <br />randomly collected "healthy" C. latipinnis, demonstrated that most of the damage was in the form of <br />compression fractures while step-down fractures were poorly represented. These compression fraclures <br />account for many of the spinal deformities found in the tlannelmouth suckers. Modifications to cathodes <br />of the electrofishing units during the study probably resulted in the reduction in spinal deformities noted <br />during the course of the study. There was nO correlation with electro fishing damage and manufacture of <br />equipment. <br /> <br />Asian tapeworm and other parasites: Asian tapeworms, Bothriocephalus acheilognathi, will remain in <br />the San Juan River as long as susceptible hOSls are present. B. acheilognathi will pose a threal to native <br />speckled dace, roundtail chub, and young Colorado pikeminnow. "leh," Ichthyophthirius multifiliis, is a <br />potential problem to young of the year fish in backwaters during the warmer water temperatures. <br />Leeches may provide areas that secondary bacteria can invade and young forms of Lernaea might have <br />an effect on fish in backwaters during periods of wanner water. All other parasites should have little or <br />no effect on fish in the future unless water quality deteriorates. <br /> <br />Virus: Since no viral evidence was found in San Juan River fishes, they are currently not a stress factor <br />in fish populations. <br /> <br />Severity of disease in the San Juau River and Summary: Since June 1992, San Juan River fish health <br />data suggests that abnormality incidence in all fish species is low with the exception of "spikes" of <br />lesions and other disease signs during the Spring hydrograph. River sections with the highest <br />abnormality incidence and bacteremia constantly have been miles 136-156. Because of the inconsistency <br />of spikes of lesions from year to year, it would suggest that the source might be triggered by monsoon <br />cyclonic storm activity from the previous summer or occasional releases from a yet unknown source. <br /> <br />8 <br />
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