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<br />COMMUNICA nONS
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<br />138
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<br />The Progressive Fish-Cu/turist 49: 138-140, 1987
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<br />
<br />Survival of Razorback Suckers Cultured in Earthen Ponds
<br />
<br />ROGER L. HAMMAN
<br />
<br />US Fish and Wildlife Service
<br />Dexter National Fish Hatchery
<br />Post Office Box 219
<br />Dexter. New Mexico 88230. USA
<br />
<br />Abstract, - Razorback sucker (Xyrauchen texanus)
<br />swim-up fry and fingerlings were successfully reared in
<br />earthen ponds at the Dexter, New Mexico, National Fish
<br />Hatchery. Swim-up fry (71 ,OOO/lb) were stocked in 0.34-
<br />l.08-acre ponds at the rate of 10 I ,000-1 09,000 fry/acre;
<br />subfingerling fish (724/lb) were stocked in 0.86-0.98-
<br />acre ponds at the rate of 51 ,000-58,000 fingerlings/acre;
<br />fingerling fish (1 58/lb) were stocked in 0.98-acre ponds
<br />at the rate 01'26,000-27,000 fingerlings/acre. Ponds were
<br />treated initially with organic and inorganic fertilizers, in
<br />addition to periodic addition of alfalfa pellets. The swim-
<br />up fry were supplementally fed a formulated trout feed.
<br />Survival ranged from 87.8 to 98.6% for swim-up fry and
<br />92.7 to 95.8% for subfingerlings and aVeraged 96.2% for
<br />fingerlings.
<br />
<br />The razorback sucker (Xyrauchen texanus) is
<br />one of the larger catostomids in western North
<br />America. It is known to reach total lengths near
<br />3.3 ft and weights of II-13 lb (Minckley 1973).
<br />Considered endemic to the Colorado River basin,
<br />it is one of the native fishes that have undergone
<br />population declines in the past century (McAda
<br />and Wydoski 1980; Wick et al. 1982; Minckley
<br />1983). Deacon et at. (I979) listed the razorback
<br />sucker as a threatened species in Arizona, Cali-
<br />fornia, Colorado, Nevada, Utah, and Wyoming;
<br />however, it is not so listed by the U.S. Fish and
<br />Wildlife Service (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 razorback sucker (Toney 1974). The
<br />program was transferred in 1981 to Dexter Na-
<br />tional Fish Hatchery, New Mexico. Although the
<br />reproductive biology (Inslee 1982; Hamman 1985;
<br />Marsh 1985) and early life history (Minckley and
<br />Gustafson 1983) have become better understood,
<br />little information has been documented concern-
<br />ing survival under culture conditions from fry to
<br />fingerling size. The purpose of this study was to
<br />present data on the survival of razorback suckers
<br />cultured during 1985 at Dexter National Fish
<br />Hatchery, New Mexico.
<br />
<br />Methods
<br />
<br />Fry culture.. - Razorback sucker swim-up fry
<br />(276,200) were stocked in February and March
<br />1985 in four earthen ponds ofO.34-I.08-acre areas
<br />and 3-4- ft a verage depths. Stockimg densities were
<br />101 ,OOO-109,000/acre. At stocking, the fry ranged
<br />from 7 1,000 to 94,000/lb among the four ponds.
<br />No significant handling mortality was observed
<br />following transplants.
<br />Approximately 7 d prior to stocking swim-up
<br />fry, ponds were treated with organic and inorganic
<br />fertilizers. Ponds received alfalfa I!>Cllets at 300 lb/
<br />acre and superphosphate at 50 Ib/acre. After the
<br />initial treatment, two 0.34-acre ponds received five
<br />weekly fertilizations of alfalfa pellets at 100 lb/
<br />acre; the 0.89- and I .08-acre ponds received three
<br />weekly fertilizations of alfalfa pellets at 100 Ib/
<br />acre and superphosphate at 25 lb/acre, respec-
<br />tively,
<br />Fry were also fed a commercial trout starter diet
<br />beginning on day I. Feeding rate was not calcu-
<br />lated, since the formulated feed was a supplement
<br />to the natural plankton present in the ponds.
<br />Subfingerling culture. - Young sub fingerlings
<br />(150,05 I) were stocked in three earthen ponds of
<br />0.86-O.98-acre areas and 3-4-ft average depths.
<br />Stocking densities varied from 51,000 to 58,000/
<br />acre. At stocking, the young subfingerlings ranged
<br />from 724 to 549/lb among the three ponds.
<br />Prior to stocking, the 0.86-acre pond received
<br />a single treatment of alfalfa pellets at 100 lb/acre.
<br />Fish were fed a commercial trout diet (numbers I
<br />and 2 granules) at a rate of 5.5%/lb of body weight
<br />beginning the day they were stocked.
<br />Fingerling culture, -Fingerlings (52,930) were
<br />stocked in two earthen ponds of 0.98-acre area
<br />and 3-ft average depth. Stocking density was
<br />26,000-27 ,OOO/acre. At stocking, the fingerlings
<br />were I 58/lb. Fish were fed a commercial trout diet
<br />(numbers 2 and 3 granules) at a rate of 5.0-3.5%/
<br />Ib of body weight beginning the day they were
<br />stocked.
<br />
<br />Results and Discussion
<br />
<br />Fry Culture
<br />
<br />Fry were reared 69-78 d; wlilter temperature
<br />varied from 47 to 7 IOF. Survival ranged from 87.8
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