WSP07867

• File Number: 8240.300.31.J
• Description: San Juan River - Environmental Studies
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 2/1/2000
• Title: Ichthyofaunal Surveys of Tributaries of the San Juan River - NM
• Water Supply Pro - Doc Type: Report/Study

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species in fish collections came from the Animas River during 1934. At this time it was
reported as the most abundant species captured during the sampling event. Historical
records from each decade suggest that the speckled dace has been one oftlle most
numerous species in most tributaries of the San Juan River. Additionally, in larger
tributaries where low numbers of speckled dace have been reported this species was
probably under represented in the data because their small size makes them difficult to
capture using certain sampling teclmiques. Speckled dace were common in fish
collections throughout the 1994 habitat use study, however individuals representing the
YOY age class were never collected, Juvenile and adult speckled dace were found
occupying all three major habitat types. Habitat use data for juvenile speckled dace
suggested that this size class occurred primarily in riffle habitat and areas of relatively
high velocity. Large numbers of speckled dace in the adult size class were located in all
three major habitat types,

CalOstomus discobo/us (bluehead sucker): The bluehead sucker is native to the San Juan
drainage. This species has been reported during most collections since the earliest
sampling efforts in this drainage, The bluehead sucker has been reported from every
major tributary of the San Juan River, and is often among the most abundant ofthe
species collected,

The bluehead sucker was well represented in collections by all three size classes during
the habitat study, YOY bluehead suckers were found using all three major habitat types,
however, most were collected from glide habitat. Juvenile bluehead suckers were mostly
collected from pool habitat in the spring and glide habitat in the fall, Habitat use data
compiled for adult bluehead suckers indicated that all three habitat types were again
utilized, however most individuals were found in areas of relatively slow velocity,

Catostomus /atipinnis (llannelmouth sucker): Flannelmouth suckers are native to the San
Juan drainage, and occur in all major tributaries. This species was well represented and
often one of the dominant species in most historical sampling efforts from 1934 to the
mid 1990s, The only locations where the llannelmouth sucker was absent or occurred in
low numbers was at the most upstream site locations or in small tributaries,

This species was well represented in collections by all three size classes during the 1994
habitat study. YOY llannelmouth suckers were found using all three major habitats
types, but most occurred in glide habitat. Although all three major habitat types were
used by juvenile and adult tlannelmouth sucker most were collected from areas of Jow
velocity.

Coitus bairdi (mottled sculpin): This species was reported from the Animas River in
1961. Since then it has been reported from most tributaries of the San Juan River, This
species appears to be most numerous in the Animas River and tributaries upstream from
Navajo Reservoir. In tributaries below Navajo Reservoir, mottled sculpin populations
were found to be locally common in areas of suitable habitat, particularly in the upstream
reaches of the La Plata River. During the habitat use study this species was only

Draft Final Tributary Report
Miller Ecological Consultants, Inc.

January 31, 2000
Page 21