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<br />Studies
<br />178.,>'"
<br />
<br />Spawning and Culture of Colorado Squawfish in Raceways
<br />
<br />Roger L. Hamman
<br />
<br />U.S. Fish and Wildlife Service, Willow Beach National Fish Hatchery
<br />P. O. Box 757, Boulder City, Nevada 89005
<br />
<br />ABSTRACT: Trials were conducted during 1980 to spawn and culture Colorado squawfish (Plychocheilus
<br />Lucius) at Willow Beach (Arizona) National Fish Hatchery. A total of 78 hatchery-reared females and
<br />5 wild females were injected with acetone-dried carp pituitary. Three wild females were not given
<br />hormonal injections. Wild fish spawned in raceways modified for trout rearing; hatchery-reared fish
<br />were hand stripped and the eggs artificially fertilized. Incubation times were 90-121 h at water
<br />temperatures of20-240C and 145-180 hat 12-130C. At hatching, total length of fry ranged from 6.0
<br />to 7.5 mm. The length of fry placed in modified raceways had doubled by day 21 and fingerlings
<br />attained a length of 42-50 mm by day 107.
<br />
<br />'The Colorado squawfish (Ptychocheilus /ucius)
<br />nee inhabited all the mainstream waters of the
<br />olc'''1do River basin. The largest native cyprinid in
<br />ortll''''America, it formerly reached lengths up to
<br />,1,8 m and weights of 36 kg (Colorado River Fishes
<br />iRecovery Team 1978), but specimens larger than 7 kg
<br />'ave not been found in the past 10 years.
<br />~,. The Colorado squawfish is believed to be extirpated
<br />the lower basin (Minckley 1973); although the fish is
<br />Mill present in much of the upper basin (Joseph et al.
<br />1977), it is considered in danger of extinction. The
<br />Colorado squawfish is listed as an endangered species
<br />)y the States of Arizona, California, New Mexico,
<br />'~evada, Utah, and Wyoming (Deacon et al. 1979) and
<br />by the U.S.' Department of the Interior (1980).
<br />~On 16 March 1978 the Colorado Squawfish Re-
<br />covery Plan, developed by the Colorado River Fishes
<br />'Recovery Team, was approved by the Director of the
<br />.U.S. Fish and Wildlife Service. The Recovery Team,
<br />n independent group of biologists operating under
<br />he sponsorship of the U.S. Fish and Wildlife Service,
<br />as three major goals: (l) to preserve, protect, and
<br />anage existing populations and habitats of Colorado
<br />uawfish; (2) to restore Colorado squawfish populations
<br />o their former range; and (3) to acquire, propagate,
<br />nd maintain captive reserve gene pools.
<br />The purpose of the present study was to develop and
<br />st techniques for the spawning and culture of
<br />olorado squawfish. The present paper reports the
<br />ccessful spawning of hatchery-reared and wild brood
<br />tock, and presents culture data for the progeny during
<br />980 at the Willow Beach (Arizona) National Fish
<br />atchery.
<br />
<br />Prog. Fish-Cult. 43 (4). October 1981
<br />
<br />Methods
<br />
<br />Brood Stock
<br />
<br />The brood stock consisted of 13 wild adults from the
<br />Colorado River, 14 wild adults from the Green River,
<br />and 130 hatchery-reared adults originally derived
<br />from the Yampa River. The Colorado River brood
<br />stock was collected between Grand Junction, Colo-
<br />rado, and Moab, Utah, on 18 November 1975, 24
<br />April 1978, and 2 November 1979. The Green River
<br />brood stock was collected between Ouray National
<br />Wildlife Refuge, Utah, and Jensen, Utah, on 13 May
<br />1976, 10 May 1978, and 26 November 1979. The
<br />Yampa River hatchery-reared brood stock were 1974
<br />year-class progeny from the first squawfish to be
<br />propagated at Willow Beach Nationai Fish Hatchery
<br />(Toney 1974).
<br />
<br />Spawning Facilities
<br />
<br />Facilities consisted offive concrete raceways (30.5 X
<br />2.4 X 1.2 m) and were designated as A3, A4, A9, AI 0,
<br />and A2. Raceways A3 and A4, and A9 and A 10 were
<br />connected to allow water recirculation to obtain the
<br />warmer temperatures (at least 21-220 C) believed to be
<br />necessary for spawning (Vanicek and Kramer 1969;
<br />Toney 1974). Water was pumped to the upper end of
<br />raceway A3 or A9 from the adjacent raceway A4 or
<br />A 10 by a I-hp fresh-flo pump at the rate of 0.02 ml/ s,
<br />flowed to the lower end, and returned to A4 or A I 0 by
<br />gravity.
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<br />173
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<br />VI
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