7339

• UCREFRP Catalog Number: 7339
• Author: Valdez, R. A.
• Title: A Review of the Hatchery Program for Threatened and Endangered Fishes of the Colorado River.
• USFW Year: 1985.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

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3-5

Inslee (1983) reported the fecundity in 18 eight year old females of
38,559 to 83,579 eggs per female for a mean of 60,676 eggs. The number of
eggs per pound ranged from 18,372 to 43,137 for a mean of 31,094.

3.2 Humpback Chub
3.2.1 Brief History

Humpback chub were fi rst subjected to a "spawni ng tri a 1" at Wi 11 ow
Beach NFH in 1980. The brood stock consisted ot~.14<wH& adu-ltsfnlllt"tflle'"> '
Little Colorado River (LCR)" and 16 wild aduTts'froflrtheUp,per Colorado Rl'er } 4./Y'2J /)
(Hamman 1982a). Fish from the LCR were collected May 17, 1978; October 17, - ~-"
1979; and June 13, 1980 near the confluence of the Colorado River in Grand
Canyon National Park, Arizona. The Colorado River fish were collected
November 5, 1979 at Black Rocks, below Grand Junction, Colorado. This first
attempt produced about 18,000 eggs and 6,500 fingerlings {Table 2).

In 1981, the previously mentioned brood stock produced about 50,000
eggs and 36,321 swim-up fry (23,940 naturally spawned and 12,381
artificially spawned). These produced 19,957 and 9,318 fingerlings,
respectively, for a total of 29,175 (Hamman 1982a). Survival from fry to
fingerl ings was 83 and 75% for naturally and artificially-spawned eggs,
respectively. In addition to the fish produced at Willow Beach NFH, about
18,000 eggs were taken from wild fish in a field spawning trial at Black
Rocks, Colorado on June 2, 1981 (Valdez and Clemmer 1982).

In 1981, the 30 wild adults and their progeny were transferred from
Willow Beach NFH to Dexter NFH, where refinements in hatchery methodologies
continued with an emphasis on examining the taxonomic problems associated
with the Gila complex (Hamman 1981a). This program has consisted of induced
hybridizat:iOil between humpback chub, roundtail chub and bony tail. The
progeny of these crosses were SUbjected to caryotyping (chromosome mapping),
electrophoresis (blood protein separation), and morphometric analyses to
determine the characteristics of wild hybrids from their domestic
counterparts and to facilitate distinctions between species intergrades
afield. No pure humpback chub were produced in the hatchery in 1982, 1983
or 1984. An additional 54 juveniles were transferred to Dexter NFH from the
Little Colorado River in August 1984.

3.2.2 Releases To The Wild '-)

Hatchery-reared ~umpback chub have been re1 eased in the wi 1 d only onc~ .}
A~p~, 7~QO hUllpb.ch, 15'"150"" TL, w,,"" r.l"_~1n~""'''1'9lltfn ____ :::;-
c.Wfoact Canyon, a whi tewater secti on of the Upper C fora-era' River "; /
immediately upstream from Lake Powell, Utah. All fish re marked with /
coded wire nose tags at Willow Beach NFH before transfer/and release. No ~
subsequent attempts have been made to recapture these fish.\ The approximate/
distribution of hatchery-reared humpback chub is presented/in Table 2. I.
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