7341

• UCREFRP Catalog Number: 7341
• Author: Valentine, J. J.
• Title: Hatchery and Laboratory Phase of the Colorado River Endangered Fishes Study.
• USFW Year: 1981.
• USFW - Doc Type: \
• Copyright Material: YES

Methods and Results

Hatcheries

Willow Beach National Fish Hatchery, Arizona and Dexter NFH, New
Mexico and the Utah Fisheries Experiment Station, Logan, Utah are
propagating Colorado River fishes for the CRFP. Willow Beach has
been the primary producer of the fish and has been supplying the other
two hatcheries and laboratories with fry, fingerlings and future
broodstock.

Colorado squawfish - A group of 27 wild adult squawfish were held
at Willow Beach for broodstock. They were collected from the Yampa,
Green and Colorado Rivers from 1973 to 1979. Also, about 2,000
squawfish were produced at the hatchery in 1974. They began to mature
in 1979 and about 500 were selected for broodstock. Of these, 100
remain at Willow Beach; 140 are at Utah FES; 270 are at Dexter, and 16
are at Utah State. Unfortunately, 14 of the wild squawfish held at
Willow Beach were stolen on November 27, 1980 and six of eight mature
females were lost.

Broodstock at Willow Beach are held in double 100 foot raceways
that are 8 ft. wide and 4 ft. deep. Several tons of gravel have been
placed in the upper 1/3 of some of the raceways where water can flow up
through the gravel. The gravel is sloped to provide depths from 0-75 cm
for the fish to spawn on. The water is from the Colorado River, unfiltered
and unsterilized. It is recirculated beginning in early spring to allow
it to gradually warm up to 700 F. over a period of months. This brings
on maturation of the fish about a month after the water temperature
reaches 68 to 700 F.

Spawning previously occurred over the gravel beds in 1974 and 1979. However,
1980 has turned out to be the best year on record. Three females were
observed releasing eggs on June 23 and 24 and produced an estimated
25,000 eggs.

Following the natural spawning, five of the wild broodstock and
10 domestic females were subjected to injections of carp pituitary to
induce spawning. The wild broodstock were released and allowed to
spawn on their own producing an estimated 40,000 eggs. In addition
approximately 1,000 eggs were hand stripped from one wild female. and
78,000 were stripped from the dom~stic broodstock. This was the first
time these methods have been used successfully on the Colorado squawfish.

Up to 95% of the wild eggs from natural spawning hatched success-
fully. But only 1,000-2,000 eggs hatched of those taken from the domestic
broodstock. Hatching usually occurred in 96 hours at 200 C.

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