BOARD00038 ‎(2)‎

• Board Meeting Date: 9/20/2006
• Description: WSP Section - San Juan River Recovery Implementation Program Document Revisions
• Board Meetings - Doc Type: Memo

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conserve listed and other native species while providing for recreational fishery
opportunities will be considered in nonnative fish management strategies developed and
implemented by the Program. This consideration will include consultation and approval
from the State wildlife agencies prior to implementation of nonnative fish management
actions.

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Agency and public understanding of the purpose and scope of nonnative fish management
actions by the Program and its participating agencies is critical to the success of the effort.
Recovery Program partners agree to support and actively participate in public
communication and involvement.

The impact of non-native species on native fish populations is an ongoing concern for the
Program. The establishment of non-native fish populations negatively impacts native fishes
through direct competition for habitat and resources or through predation. While many large
bodied non-native fish species occur throughout the San Juan River, the Program's research
results show that the most abundant and widespread is the channel catfish. The earliest report of
channel catfish in the San Juan basin was 1957, but it is likely the species was present prior to
this. Channel catfish occupy all available habitat types on a year-round basis, exhibit localized
movement, and the larger individuals prey upon native fish. Channel catfish survive within the
San Juan River without substantial exploitation from humans.

The second most abundant large bodied non-native fish in the San Juan River is the common
carp. The first introductions in New Mexico occurred in 1883 from stock produced by the US
Fish Commission. Common carp occupy a wide variety of habitats in the river and constitute a
large proportion of the total weight of fish present due to their omnivorous feeding habits. The
common carp is often considered a pest species because it alters habitat through increased
turbidity, uproots aquatic vegetation, feeds on the eggs of more desirable species and is not
considered a favorable food fish in the United States.

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In addition to channel catfish and common carp, Program survey revealed the presence of three
lake fish species including threadfin shad, walleye and striped bass. The source of these fish is
believed to be the inundation of the waterfall at river mile (RM) 0.0 at Lake Powell, which
occurred in the spring of 1995.

Opportunistic removal of non-native fishes began in 1996 and was formally adopted as a
management tool in 1998. The Service's New Mexico Fishery Resources Office (NMFRO)
evaluated numerous capture techniques and determined that raft mounted electrofishing was the
most efficient method to remove large bodied non-native fish. Removal efforts by NMFRO
officially began in 1998 with intensified efforts beginning in 2001. Efforts focused on a 7.6-mile
reach of river located near Fruitland, New Mexico, between the Hogback diversion dam and the
San Juan Generating Station diversion weir. Data suggested that large adult channel catfish and
common carp were common in this reach and were limited upstream of the San Juan Generating
Station diversion weir. Efforts in 2004 marked the fourth consecutive year of removal between
the San Juan Generating Station and the Hogback diversions (RM 166.6 - 159.0).

Due to seasonal variance in catch rates of non-native fishes, efforts have been expanded to
include an additional 11.1 river miles immediately downsteam from the Hogback diversion dam.
Mark/recapture work conducted by NMFRO documented upstream movement into the study
reach by channel catfish and common carp. These movement patterns correspond to the
construction of a non-selective fish ladder completed in 2001 at the Hogback diversion dam. The

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