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<br />~ Fish health surveys on the San Juan River from Fannington, New Mexico, to Clay Hills, Utah, were
<br />00 initialed in October 1992 by Pinetop Fish Health Center (PFHC) personnel. The goal of the survey was
<br />to detennine the cause of lesions and other abnonnalilies observed in native and nonnative fish. This
<br />report summarizes the fish health findings in San Juan River fish from October 1992 through May 1999.
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<br />INTRODUCTION:
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<br />The investigations focused on the tlannelmouth sucker, Catostomus latipinnis, as it is Ihe most prevalent
<br />fish species sampled and had been the most susceptible species to abnormalities, including lesions.
<br />Gaufin, Smith, and Dotson (1960) had reported a similar situation with C. latipinnis in the Green River,
<br />Wyoming. For these reasons, C. latipinnis was used as an indicator species of environmental stressors or
<br />diseases. When present, these stressors also may affect the endangered Colorado pikeminnow
<br />(squawfish), Ptychocheilus lucius, razorback sucker, Xyrauchen texanus, and other fish species in the
<br />San Juan River.
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<br />Fish health sampling included: I) field observations (e.g., eCloparasite and endoparasite identificalions,
<br />and noting the incidence of internal and external abnonnalities), and 2) subsequent laboratory
<br />investigations including viral assays, bacterial identifications, and histological examinations. Fish also
<br />were examined for electro-induced damage including
<br />spinal deformities and damaged kidney tissue.
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<br />MATERIAL AND METHODS:
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<br />Fish health personnel accompanied fishery biologists on San Juan River adult moniloring trips from
<br />Hogback, New Mexico, to Mexican Hat, Utah. Additional trips were made to sample fish from Mexican
<br />Hat to Clay Hills, Utah, and Farmington to Hogback, New Mexico. All fish were collected using rafts
<br />mounted wilh electro fishing apparatus. All fish species with abnormalities were noted, including but not
<br />limited to: bluehead sucker (Catostomus discobolus), tlannelmouth sucker (c. latipinnis), razorback
<br />sucker (X texanus), channel catfish (/ctalurus puncta/us), Colorado pikeminnow (P. lucius), roundtail
<br />chub (Gila robusta), common carp (Cyprinus carpio), red shiner (Cyprinella lutrensis), fathead minnow
<br />(Pimephales promelas), and speckled dace (Rhinichthys osculus). Fishery biologists noted and saved
<br />fish with lesions, tumors, and missing or deformed eyes for subsequent observations by fish health
<br />personnel. For purposes of this report, a lesion is defined as an abnonnal change in skin structure due to
<br />injury and/or infectious disease. Disease, defined as lack of ease or as a stressed condition, encompasses
<br />all abnormalilies in this report. Other stressors including leeches and obvious predator-inflicted wounds
<br />were noted by biologists, but were not considered abnormali ties.
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<br />Field notes were obtained from the fishery biologists and analyzed for the number of each taxa collected
<br />and what types of abnormalities were observed. This provided a river mile by river mile accounting of
<br />observations for a large number of fish.
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<br />In May 1994, fish health personnel initiated disease "inspections" of randomly selected C. latipinnis
<br />from all electrofishing boats. The purpose of the inspections were I) to supplement disease samples
<br />collected by fishery biologists, 2) to ascertain health status of apparently healthy and moribund fish in
<br />regular intervals throughout the sampling region, and 3) to use C. latipinnis as an indicator species of
<br />potential environmental hazards affecting other animal and plant life in the San Juan River. Inspections
<br />were performed on a random five-fish sample every designated mile (every fifth river mile).
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