9408

• UCREFRP Catalog Number: 9408
• Author: Foster, D. K. and G. Mueller.
• Title: Movement Patterns, Behavior, and Habitat Use of Razorback Sucker Stocked Into the Green River at Canyonlands National Park, Utah.
• USFW Year: 1999.
• USFW - Doc Type: Open-File Report 99-107,
• Copyright Material: NO

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Habitat Use
Razorback suckers in both treatments utilized all available habitats, current intensities,
and water depths during the first 2 weeks and altered their patterns of habitat use over
time. However, the two treatments differed in their habitat utilization patterns. Initially,
the majority of control suckers were located in shallow (<1.2 m) regions with slow
current (<1.4 km/hr), while experimental fish were most often observed to utilize deep
water (>3 m) that was either slow or swiftly flowing (>4.8 km/hr). Nine of 19 razorbacks
were utilizing channel habitat during the first 14 days. During the 15 to 29 day period
following release, both treatment groups were occupying slow, near-shore habitats and
deep eddy pools. Only one razorback sucker was observed to utilize channel habitat
during this period. This experimental treatment fish had moved 72 km up the Colorado
River and was returning downstream towards the Green River confluence by way of the
main channel. During the 30 to 58 day period since release, seven of the ten fish that
could still be located were found in deep water (>3 m), and f ve fish were now utilizing
channel habitat. Three of the razorbacks utilizing water greater than 3 m deep were
located near flooded canyon mouths (2) or moving down lake (1) in Lake Powell.
The pattern of razorback sucker habitat use during the initial 14 days was similar to that
observed by Burdick and Bonar (1997) in wild razorback sucker in the Gunnison River.
The pattern of habitat utilization was proportionally 21% (60%) channel, 21% (19%)
eddy pool, 21% (26%) backwater, and 37% (7%) near shore [parenthesis denote data
taken from Burdick and Bonar (1997)]. The most obvious difference in the habitat
utilization rates is that instead of utilizing mainly channel habitat, the razorback suckers
in this study were found most often near shore as opposed to the channel.
However, this pattern changed during the 30 to 58 day period. During the last 4 weeks of
the project, the majority of razorback sucker contacts (52%) were now in the main
channel, 37% were still in near shore habitat, and 11% of contacts were in eddy pools.
These results contrast with the 1994 and 1995 San Juan stockings in which razorback
sucker utilized chiefly channel habitat (Ryden and Pfeifer 1996). However, Ryden and
Pfeifer (1996) observed that razorback suckers show seasonal variability in habitat
utilization patterns. Perhaps the razorback suckers in both this experiment, as well as
those of Ryden and Pfeifer (1996), were utilizing deep channel habitat in August, not
only because it was the most abundant habitat type (~-75% of all habitats in the San Juan
River), but perhaps in order to seek out a preferred temperature as well. Bulkey and
Pimentel (1983) utilized electronic shuttle box experiments to deduce that razorback
suckers' preferred temperature lies between 22.9 and 24.8 °C. The thermal profile of the
Green River within Canyonlands National Park during August of 1998 is unfortunately
unknown.
A surprising finding was a significant correlation between the condition factor of a fish
and the depth of water that it utilized. Razorback suckers that utilized habitats of
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