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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sucker to depart the backwater remains unknown, but all the fish had departed the
backwater within 5 days (the number of days until the next sampling occurred).
One short telemetry survey was made on June 17 to determine the locations of the 30
control (not-acclimated) fish that were released on June 16 and 17. Five razorback
suckers were located approximately 5 km below the release site. Three of these fish had
entered Anderson Bottom backwater, which is the first backwater downstream of the
release point. Three of these five control fish were later located in backwaters further
downstream 5 days later. Twenty-nine percent (4 of 14) of control razorback suckers
were observed to utilize backwaters during the first 2 weeks, two fish at least twice.
However, since sampling occurred on just 3 days during the first 2 weeks, the actual
number of control suckers that utilized backwater habitats was probably larger. Stocked,
non-acclimated razorback suckers seek and enter backwaters as they move downstream
following release. This rate of backwater use by stocked razorback sucker is much higher
than that observed by Ryden and Pfeifer (1995) in 1994 and 1995 on the San Juan River,
but is similar to the rates of backwater use seen in wild razorback suckers in the Colorado
(18% of contacts) and Gunnison (26% of contacts) Rivers (Burdick and Bonaz 1997).
Fourteen of the 15 control razorback suckers were found following release and all had
moved downstream. Only one control group razorback sucker was not located, and since
no fish were found on June 19 in the 28 km of river above Millazd Bottom, it is very
likely that all 15 control razorback suckers moved downstream following release.
The majority of dispersal occurred during the first 2 weeks for both the control and
experimental treatment groups (Figure 6.) By day 14, the mean maximum dispersal of
the experimental fish was actually further than the control fish (59 vs.43 km). The
dispersal distance of the control fish is probably an underestimate because two control
fish that were located ~5 km from the release point on day 1 were never located again,
and if they behaved similazly to the other 12 control fish, they would have continued to
move downstream. By day 29, the mean maximum dispersal distance increased to
approximately 71 km. During the final period of the study, days 30 to 58, the control
razorbacks continued to increase their dispersal distance to 81 km while the experimental
razorbacks decreased their average dispersal distance to 53 km. Although differences in
dispersal were similaz, a greater proportion of control razorback suckers traveled
downstream upon reaching the Colorado River than did experimental suckers. Ten of
14 control fish entered either Catazact Rapids or Lake Powell by day 58, whereas only
2 of 9 experimental fish were found that faz downstream. However, due to large
variability between individual fish and a low sample size, these modest treatment (p =
0.74) and time period (p = 0.12) effects were not statistically significant. Similar
dispersal distances for both hatchery- and pond-reazed razorback suckers stocked into
rivers were observed in the San Juan River during 1994 (-62.3 km) and 1995 (-95.5 km)
(Ryden and Pfeifer 1995) and in the Green River during 1995 (week-1 = -39.2km, week-
3 _ -87.1 km) (Day and Modde 1999).
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