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<br />The Progressive Fish-Cul/urisl 51 :27-29, 1989
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<br />COMMUNICA nONS
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<br />Survival of Colorado Squawfish Cultured in Earthen Ponds
<br />. .
<br />
<br />ROGER L. HAMMAN
<br />
<br />U.S. Fish and Wildlife Service
<br />Dexter National Fish Hatchery
<br />Post Office Box 219
<br />Dexter, New Mexico 88230, USA
<br />
<br />W.
<br />rial
<br />J.S.
<br />85-
<br />
<br />Abstract. -Swim-up fry and fingerlings of Colorado
<br />squawfish (Ptychocheilus lucius) were successfully reared
<br />in earthen ponds at the Dexter, New Mexico, National
<br />Fish Hatchery. Swim-up fry (95,340-104,420/1b) were
<br />stocked in 0.89-O.98-acre ponds at the rate of 105,316-
<br />137,438 fry/acre; fingerling fish (980-I,088/Ib) were
<br />stocked in 0.98-1.08-acre ponds at the rate of 52,978..,.
<br />55,424 fingerlings/acre. Ponds were treated initially with"
<br />organic and inorganic fertilizers in addition to periodic
<br />applications of alfalfa pellets. Swim-up fry were supple-
<br />mentally fed a formulated trout feed. Survival ranged
<br />from 27.7 to 36.0% for swim-up fry and averaged 92.2%
<br />for fingerlings:
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<br />The Colorado squawfish (Ptychocheilus lucius)
<br />is presently being cultured at Dexter National Fish
<br />Hatchery, New Mexico. The largest native cypri-
<br />nid in North America, it formerly reached lengths
<br />up to 6.0 ft and weights of 80 Ib (USFWS 1978),
<br />but specimens larger than 15 Ib have rarely been
<br />found in the past 15 years. Considered endemic
<br />to the Colorado River basin, it is one of the na-
<br />tive fishes that have undergone population de-
<br />clines in the past century (Behnke and Benson
<br />1980; Holden and Wick 1982). The Colorado
<br />squawfish is believed to be extirpated in the lower
<br />basin (Minckley 1973); although it is stiIl present
<br />in much of the upper basin (Joseph et al. 1977),
<br />it is considered in danger of extinction. Deacon et
<br />al. (1979) listed the Colorado squawfish as an en-
<br />dangered species in the states of Arizona, Califor-
<br />nia, Colorado, New Mexico, Nevada, Utah, and
<br />Wyoming. It is also listed as endangered by the
<br />U.S. Department of the Interior (1980; see also
<br />Johnson and Rinne 1982).
<br />In 1974, a propagation program was started at
<br />Willow Beach National Fish Hatchery, Arizona,
<br />to test and develop techniques for spawning and
<br />rearing the Colorado squawfish (Toney 1974). The
<br />program was transferred, in 1981, to Dexter Na-
<br />tional Fish Hatchery. Although the species' repro-
<br />ductive biology (Hamman 1981, 1986) and early
<br />Iife.,b~Sfory (Marsh 1985) have become better
<br />un~od, little has been documented concern-
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<br />ing its survival under culture conditions from fry
<br />to fingerling size (Hamman 1981). The purpose of
<br />this paper is to present data on the survival of
<br />Colorado squawfish cultured during 1987 at Dex-
<br />ter National Fish Hatchery.
<br />
<br />Methods
<br />
<br />Spawning techniques used during this study were
<br />those described by Hamman (1981,1986). Twen-
<br />ty-five Colorado squawfish females (1974 year
<br />class) were induced to spawn by injecting them
<br />with acetone-dried carp pituitary. Average weight
<br />of females was 4.7 Ib; mean fecundity was 82,576
<br />eggs.
<br />Fry culture. -Colorado squawfish swim-up fry
<br />(337,620) were stocked in June 1987 in three 0.89-
<br />0.98-acre earthen ponds of 3-ft average depths.
<br />Stocking densities were 105,316-137,438 fry/acre.
<br />At stocking, the fry ranged from 95,340 to 104,420/
<br />Ib among the three ponds. No substantial handling
<br />mortality was observed.
<br />Approximately 10 d before swim-up fry were
<br />stocked, ponds were treated with organic and in-
<br />organic fertilizers. Ponds received alfalfa pellets at
<br />300 Ib/acre and superphosphate at 50 Ib/acre. Af-
<br />ter the initial treatment, ponds received six weekly
<br />fertilizations of alfalfa pellets at 100 lb/acre.
<br />Chemical and physical characteristics of incoming
<br />water supply to ponds is shown in Table 1.
<br />
<br />TABLE I.-Water analysis summary for water well 1
<br />at Dexter National Fish Hatchery, New Mexico.
<br />
<br />Variable
<br />
<br />Sodium (Na)
<br />POlassium (K)
<br />Calcium (Ca)
<br />Magnesium (Mg)
<br />Chloride (CI)
<br />Sulfale (S04)
<br />Bicarbonate (HC03)
<br />Total iron (Fe)
<br />Silica (Si02)
<br />Total solids
<br />Total hardness (CaC03)
<br />Alkalinity (CaC03)
<br />Nitrate (N03)
<br />Conductivity (250C)
<br />pH
<br />Temperature
<br />
<br />Concentration
<br />or measure
<br />
<br />317 ppm
<br />5 ppm
<br />513 ppm
<br />199 ppm
<br />340 ppm
<br />1,955 ppm
<br />158 ppm
<br />0.01 ppm
<br />27 ppm
<br />3,680 ppm
<br />2,100 ppm
<br />260 ppm
<br />2.5 ppm
<br />3,900 "S/cm
<br />7.35
<br />640F
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<br />27
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