7315

• UCREFRP Catalog Number: 7315
• Author: Colorado Water Conservation Board.
• Title: State of Colorado Hatchery Feasibility Study for Endangered Fishes of the Colorado River Basin, Vols. 1 & 2.
• USFW Year: 1993.
• USFW - Doc Type: \
• Copyright Material: NO

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REFERENCE NUMBER:

024

CITATION:

Marsh. P.e. 1985a. Effect of incubation temperature on survival of
embryos of native Colorado River fishes. The Southwestern
Naturalist 30(1):129 - 140.

BT, cs, HB, RZ, RZ_EGG, RZ_LAR. HB_EGG, HB_LAR.
BT_EGG, BT_LAR. CS;..EGG, CS_LAR

Temperature, LiCe History, Water Quality, Culture, Re:seardl

SPECIES AND LIFE STAGE:

TOPICS:

KEYWORDS:

COLORADO SQUAWFISH, BONYTAIL, HUMPBACK CHUB,
RAZORBACK SUCKER, INCUBATION TEMPERATURE,
EOGS, ABNORMALITIES. 'I'L. INCUBATION APPARATUS

SUMMARY: Eggs of Colorado squawtish, Razorback sucker, Humpback chub, and bonytail were held at 5,
10, 15, 20, 25, and 30" to determine effects of incubation te~perature upon hatching and
survival.

Six 22 liter glass aquaria were maintained at experimental temperatures with a combination
of cold water infiow and thermostatically-conuolled immersion-type heaters. The 30" tank had
no tlow and the other 5 tanks had a 1.0 literlh inflow. Incubation chambers were made of 76
mm ID PVC pipe fitted on the bottom with 0.5 mm-mesh nylon netting. Six to eight
chambers were suspended in each aquaria. The water was obtained from the wells at Dexter
National FISh Hatchery (DNFH), ~ and was cIwacterized by relatively high salts especially
sulfate 1900-1930 mglL, nitrate 11.1-12.0 mglL, and conductivity 3830 - 4500 umbos, ZSOC A
fun repon of water quality of DNFH wells can be reviewed in the body of this paper.

Broodstocks were obtained from wild populations in Lake Mohave and the Little Colorado
River, or as hatchery-bred fish from Willow Beach National FISh Hatchery, AZ. and held at
DCIter NFH. As sexual readiness approached, 1-2 females and 5-20 males of each species
respectively were brought from ponds to indoor tanks at 17.5 -lSOe. Adults were injected with
one or both human chorionic gonadotropin or acetone-dried carp pituitary. Eggs were
stripped, fenilized and water hardened for 1 - 2.5 h at l7.5-lSOC. After hardening eggs were
siphoned into incubation chambers. Eggs of Razorback sucker were treated daily with 1.0%
fornu'1<lehyde for 10 min until embryo motility was observed within the chorion.

Razorback sudcer - All embryos incubated at 5, 10, and 300c died. Greatest success was
acbieYed at 20 and ZS"C with significantly lower success at 150C Tune to hatch was 216 h at
lSOC and 84 h at ~c. ProlaIvae were 6.5 - S.6 mm TL, active and squirming on the bottom.
Swim-up was attained at 103 - 312 h depending on temperature. Swim-up fry were 8.4 - 8.6
mm 11. and stunting and deformities were significantly lower at 20"C (8.1%) than either 15 or
ZSOC (38%).

Bonytail - No hatch occurred at 5, 10, or 300C (0.5% hatch at 250C). Hatching success was
not significantly different for 15, ZO"c. TIme to hatch varied from 204 h at 150C to 103 h at
zooc. Prolarvae averaged 6.0 - 6.3 mm TL. Prolarvae remained quiescent on the bottom
unless disturbed. Many laIvae adhered to sides of incubation chambers with the anteroventral
portion of their head. Swim-up occurred at 148 - 396 h increasing towards lower temperatures.
Swim-up length was 8.1 - 8.6 mm TL. Incidence of abnormalities ranged from 0 - 4% not
related to temperature.

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