7990

• UCREFRP Catalog Number: 7990
• Author: Tyus, H. M.
• Title: Razorback Sucker ‎(
• USFW Year: 1997.
• Copyright Material: NO

1
1
1

1

1

Ulmer 1983, Bozek et al. 1990, Minckley et al. 1991). Model-Ulmer (1983) observed
spawning activity in Senator Wash Reservoir in water depths of 10 to 18 m. In Lake
Mohave, razorback suckers were observed spawning in water up to 5 m deep, with
most fish in less than 2 m of water. Minckley et al. (1991, p. 320) summarized
spawning in Lake Mohave as follows:
"In Lake Mohave, males stage over coarse, wave washed cobble in
water 0.5-5 m deep. Groups of up to several hundred fish ... move slowly a
meter or less from the bottom or lie immobile near or on the substrate for
hours. Based on trammel netting, females remain in deeper water until ripe,
then appear singly on the spawning grounds ... When she is ready to
spawn, a female, flanked by two or more males, separates from a group and
moves to the- bottom The males press closely against the female's posterior
abdomen and caudal peduncle, and all contact and agitate the substrate for
three to five seconds in apparent spawning convulsions after which they
typically return to a larger group... The entire sequence lasts from a few
seconds to three minutes, usually the former. Females recognizable
because of an injury or some other distinctive feature have been observed
to spawn repeatedly in a given hour and day, and on successive days within
a week."
Riverine habitafs. The reproductive ecology of riverine razorback suckers has
been most intensively studied in the Green and Yampa rivers (McAda and Wydoski
1980, Tyus 1987, Tyus and Karp 1990). Staging occurs in flooded lowlands and
eddies formed in the mouths of tributary streams, and then the fish move to main-
channel sand, gravel and cobble bars for egg deposition (Tyus 1987, Tyus and Karp
1990). Radiotracking and recaptures of tagged fish suggested that fish were homing to
only two spawning areas in this river reach (Tyus and Karp 1990).
13