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

. REFERENCE NUMBER:
CITATION:

oos

I-famman, R.1... 1982a. Induced spawning and culture of bonytail
chub. Progressive FISh-Culturisl 44(4): 201-203.

SPECIES AND LIFE STAGE:

BT, BT_EGG, BT_LA&. BT_ADU

TOPICS:

Life History, Disease, Production, Culture techniques, Water Quality,
Temperature, Diet

KEYWORDS:

ARTIFICIAL SPAWNING, EGG INCUBATION, REARING,
DIET, PARASITISM, ICTHOPHTHIRUS, DISEASE
TREAlMENT, LARVAE SURVIVAL

SUMMARY:

Brood stock were collected form Lake Mohave 1979 - 1981. Total lengths of 6 females ranged
from 487 - 564 IIlJD, weight ranged from 956 - 1,500 g. Males ranged from 454 - 480 mm n..,
and 728 - 870 g in weighL Females were induced to spawn with intraperitoneal injections of
4 mg acetone-dried carp pituitary per kilogram of body weigbL Five of the 6 females ovulated
after 18 - 20 h. FISh were anesthetized prior to injections, and held in 20 -210C flow-through
tanks. Mean fecundity was 25,090 eggs or 21,514 eggslkg body weighL When slight pressure
expelled eggs, they were collected in plastic pans. Milt from 1 male was mixed with sperm
diluent (12,000 mgIL) and added to the eggs, which were then stirred and washed for 45 Olin.
Water hardening took place for 50 mill. then eggs were placed on screen trays (1.4 nun
hardware cloth) and tilted 30" to incoming water.

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Eggs were maintained in flowing systems (7.5 LImin) at three temperatures. Eggs at 20 -210C
hatched after 99 -174 h with 90% survivaL Eggs held at 16 - 1~ hatched after 170 - 269 h
with 55% survival. Eggs held at 12 -130C hatched after 334 - 498 h with 4% survival. Larvae
in each case emerged 6.8 mm TI., and began swimming to the surface 48 -120 h after hatching.
Optimum temperature for reproduction is 20 - 210C. Eggs in cOld water suffered 96%
monaIity.

Frywere transferred after swim-up to lightly fenilized (ammonium phosphate and trout staner)
circuJating raceways 30 x 2.4 x 1.2 m. Fry swam in schools and fed on zooplankton for 21 days
after which they were fed commercial trout staner (0.25 - 0.5 kg/day 4 - 5 times per day). By
28 days mean TL was 18.1 nun, and after 70 days 49.5 mID, 97.5 g. Survival after 70 d was
71%.

Water temp in raceways varied from 12.8 - 24.40C, carbon dioxide from 1.8 _ 4.4 mg/L,
ammonia nitrogen from 0.01 -0.81 mg/L, dissolved oxygen from 7.6 - 10.0 mgIL and pH from
7.8 to 9.0 units. On day 42 lcthophthirus multifilis was found on two dead fish. Three
treatments on alternate days of fOrmalin at 15 mg/L were used. Weekly prophylactic
treatments were continued.

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