8010

• UCREFRP Catalog Number: 8010
• Author: Montagne, M.
• Title: The Grand Valley Propagation Facilities - 1997 Annual Report.
• USFW Year: 1998.
• USFW - Doc Type: Grand Junction, CO.
• Copyright Material: NO

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Fifteen wild humpback chubs were captured from Black Rocks on the Colorado River and placed
in refugia at Horsethieffor future use as brood stock. All fifteen of these fish died in 1997.
However, they spawned naturally in 1997 and their offspring are currently held at Horsethief
Also 300 F2 bonytails collected from a natural spawn at Dexter NFH and raised at Valley City
NFH were transferred to Horsethiefin October 1995. Most of these bonytails died over the
winter, but four survive and are currently held at Horsethief Six family lots from the1994 year
class of razorbacks spawned at Horsethief and Ouray NFH and then reared at Bellvue SFH were
returned to Horsethief. Of those six lots, 50 fish are currently held at Horsethief as future
broodfish.

1996

In May of 1996, existing razorback broodfish from Horsethiefwere spawned and produced ten
family lots of eggs. Three other lots were produced for use in experiments evaluating the effects
of selenium on survival and growth of razorback eggs and larvae. The eggs were transferred to the
24 Road Hatchery where they were hatched and reared for their first year. In April of 1997, 1,111
of these razorbacks were returned to Horsethief for use as future broodstock (see 24 Road
Hatchery results). These fish became infected with the bacterial disease columnaris (Flexibacter
columnaris) and most of them died. Forty eight of these fish are now held at Horsethief. The
1992-year-class offspring from San Juan arm of Lake Powell razorbacks were transferred to
Horsethiefin 1996. They had previously been reared at Bellvue SFH and Wahweap SFH (Utah).
One hundred and forty of these fish are currently held at Horsethief.

1997

On April 23, 1997 razorback brood fish from HorsethiefPonds were used in paired matings and
produced 17 family lots of eggs. The eggs were transferred to the 24 Road Hatchery to be
hatched. However, only 4 of the 17 lots hatched successfully and are currently being reared there.
(See 24 Road Hatchery results) In June of 1997, 14 Green River razorback suckers were
transferred to Horsethief from Ouray NFH. Eleven of these fish survived and will be used as
broodstock in the future. As mentioned earlier, 1,111 1996-year-class razorbacks reared at the 24
Road Hatchery were returned to Horsethief as future brood stock. Forty-eight of these fish have
survived and are currently held at Horsethief.

Problems

Disease has been the main source of mortality at Horsethief and continues to be a big problem.
While mortalities are inevitable and occur year round, mortalities due to disease become a serious
problem during the hottest months (July and August). Lernaea (Lernaea sp.), gill amoeba
(Trichophyra sp.), columnaris (Flexibacter coJumnaris), black grubs (Neascus sp.) and
myxosporean (Myxobolus sp.) take a heavy toll on fish held at Horsethief. The fish often suffer

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