7984

• UCREFRP Catalog Number: 7984
• Author: Maddux, H. R., L. A. Fitzpatrick and W. R. Noonan.
• Title: Colorado River Endangered Fishes Critical Habitat - Draft, Biological Support Document.
• USFW Year: 1993.
• USFW - Doc Type: Salt Lake City, Utah.
• Copyright Material: NO

affected by loss of seasonally flooded habitats due to their impoundment via dams and dikes,
loss of fish access, and alteration of the duration and magnitude of spring flooding.
In nonreproductive periods, adult razorback suckers tend to utilize eddies, backwaters and
other types of pool habitats (Minckley et al. 1991). Adults in the upper Green and Colorado
rivers use backwaters and eddies 2.0 to 11.0 feet deep with sand or silt substrates and water
velocities of 0.3 to 2.0 feet per second during this time (Valdez 1982a; Tyus et al. 1982b;
Tyus 1987). Radio telemetry data on razorback suckers in the Verde River indicated that
deeper pools and glides with low water velocities were most often occupied (Creef et al.
1992). Other radio telemetry work on razorbacks in the Gila River indicated that flat-water
areas in the main channel as well as pools and eddy habitats were used (Marsh and Minckley
1991). Adult razorback suckers survive successfully in reservoirs, although information on
specific habitat use outside of the breeding season is not available. Summer riverine habitat
use included deeper eddies, backwaters, holes, and midchannel sandbars (Tyus and Karp
1990; Minckley et al. 1991). Tyus and Karp (1989), based on capture and inspection of
adult razorback suckers in flooded habitats, believed that flooding of bottomland during
spring runoff was important to adults for feeding. The flooding of bottomlands provides
access to areas for feeding and also supplies nutrient and organic input into the river.
MOVEMENT/MIGRATION
Razorback suckers exhibited a variety of local and long-distance movements during the
spring spawning period. Tyus and Karp (1990) reported that 17 radiotagged fish undertook
spawning migrations of 19 to 66 miles. Osmundson and Kaeding (1989) reported movement
of 7 to 12 miles within the Grand Valley. McAda and Wydoski (1980) reported movement
of spaghetti tagged fish 16 to 86 miles although most individuals were recaptured close to the
point of release. Similar movements were noted by Tyus (1987), and historical accounts also
reported spring spawning movements of razorback suckers (Jordan 1891; Hubbs and Miller
1953; Sigler and Miller 1963).
Except for spawning migrations, razorback suckers are relatively sedentary, moving only a
few miles over several months (Tyus 1987; Tyus and Karp 1990). Valdez and Masslich
(1989) tracked 17 razorback suckers in the winter on the Green River, and they found that
most of the fish moved less than 3 miles. The radio-telemetered razorback suckers used
slow runs, slack waters, and eddies. They were found in depths of 2.0 to 4.6 feet and
velocities of 0.1 to 1.1 feet per second. Osmundson and Kaeding (1989) reported that pools
and slow eddies were predominantly used from November through April, runs and pools
from July through October, runs and backwaters during May, and backwaters and flooded
gravel pits during June. Selection of various depths changed seasonally; mean depths were
3.0 to 3.3 feet during May and June, 5.3 to 5.4 feet from August through September, and
6.6 to 7.1 feet from November through April. In Lake Mohave, mark and recapture data
shows razorback suckers moved up, down, or across the lake 2.5 to 16 miles. (Marsh and
Minckley 1989). Some individuals remained in the same locality, while one fish moved
uplake 5 miles in less than two days.
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