WSP07323

• File Number: 8240.300.31.J
• Description: San Juan River - Environmental Studies
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 10/3/1996
• Title: Biological Opinion on the Proposed Experimental Stocking of Early Life Stage Colorado Squawfish in the San Juan River
• Water Supply Pro - Doc Type: Biological Opinion

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River" (U,S. Fish and Wildlife Service 1987!. include the capture and removal of razorback
suckers from all known locations for genetic analyses and development of discrete brood
stocks if necessary. These measures have been undertaken to develop refugia populations
of razorback sucker from the same genetic parentage as their wild counterparts such that,
if these fish are genetically unique by subbasin or individual population, then separate
stocks will be available for future augmentation. Such augmentation may be a necessary
step to prevent the extinction of razorback suckers in the Upper Basin.

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Habitat requirements of young and juvenile razorback suckers in the wild are largely
unknown, particularly in native riverine environments. Life stages, other than adults, have
been extremely rare in the Upper Basin in recent times. One confirmed capture of
razorback sucker juveniles in the Upper Basin was in the Colorado River near Moab, Utah
(Taba et al. 1965). The only capture in recent years was the 1991 collection of two early
juvenile razorback suckers in the lower Green River, 89.5 km above the confluence with
the Colorado River (Gutermuth et al. 1994).

Because razorback suckers are so rare in the San Juan River and spawning or recruitment
have not been documented, an experimental stocking program has been initiated. In
March of 1994, fifteen radio.tagged razorback sucker were stocked in the San Juan River
at Bluff, Utah (RM 79.6); near Four Corners Bridge (RM 117.5); and above the Mixer in
New Mexico (136.6), In November of 1994 an additional 15 radio-tagged adults were
stocked as well as 656 PIT-tagged fish in the same locations as well as an additional site
just below the Hogback Diversion in New Mexico (RM 158.5). Monitoring found that
these razorback suckers used slow or slackwater habitats such as eddies, pools,
bacKwaters, and shoals in March and April and fast water 92.2% of the time in June and
August (Ryden and Pfeifer 1995bl. During 1995 both radio-tagged fish and PIT tagged
fish were contacted or captured. Razorback suckers were found in small numbers from
the Hogback Diversion (RM 158.6) to 38.1 river miles above Lake Powell (Dale Ryden,
U.S. Fish and Wildlife Service, pers. comm.)

Critical Habitat

Critical habitat has been designated within the 100-year floodplain of the razorback
sucker's hIstorical range in the following section of the San Juan River Basin (59 FR
13374).

New Mexico, San Juan Countv: and Utah. San Juan County. The San Juan River, -
from the Hogback Diversion in T. 29 N., R. 16 W.. section 9 to the full pool
elevation at the mouth of Neskahai Canyon on the San Juan arm of Lake Powell in
T. 41 S., R. 11 E., section 26.

PROJECT AREA

The San Juan River originates in the mountains of southwestern Colorado and flows
southwesterly into the Navajo Reservoi'r situated on the Colorado/New Mexico border.
Downstream of the Navajo Dam, the San Juan River continues westerly, flowing past the
towns of Archuleta, Blanco, Bloomfield, Farmington, Fruitland, and Shiprock, New Mexico.

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