7133

• UCREFRP Catalog Number: 7133
• Author: Jensen, B. L.
• Title: Role of Fish Culture in Endangered Fishes Recovery
• USFW Year: 1986
• USFW - Doc Type: Transactions of the Bonneville Ch. of the AFS
• Copyright Material: YES

Verde Rivers). A total of 54,135 bonytail fingerlings have been
stocked in Lake Mohave, AZ. Other transplanted species include
Yaqui chub, Gila topminnow and desert pupfish.
In addition to stocking historic habitats in an effort to recover
native fishes, live fish have been provided to several aquariums
and both live and preserved fish have been provided to numerous
Federal and State agencies and academic institutions. This aspect
of fish culture allows scientific studies to be carried out
without impacting extant populations of these native fishes which
are already severely depressed.
FISH HEALTH
As with any fish culture operation, fish health at Dexter NFH is a
primary concern. Because the hatchery water supply is pumped and
is therefore fish free, disease problems have not been a serious
problem at Dexter although some parasites have caused concern.
Although treated prior to and/or after shipment to Dexter, the
anchorworm (Lernaea sp.) was introduced with Colorado squawfish
and bonytail from Willow Beach NFH and with razorback sucker from
Lake Mohave, AZ. Present after 1979, this parasitic copepod was
finally eradicated from the station in 1984. The Asian tapeworm
(Bothriocephalus acheilognathi) was detected in Colorado squawfish
in 1982 and beautiful shiner in 1983. This parasite is thought tc
have been introduced via Colorado squawfish from Willow Beach NFH
or beautiful shiner from the Rio Casas Grandes, Chihuahua, Mexico.
Although the broodstock tested positive through 1984, no young-of-
the-year have tested positive while still on the hatchery.
Colorado squawfish brood were created with di-N-~SUtyl-tin oxide in
1984 and tested negative for Asian tapeworm in 1985. Treatment of
beautiful shiner is currently underway. A parasitic fungus
(Ichthyophonus hofferi) was diagnosed in Comanche Springs pupfish
in 1981 (Inslee 1983). The central nervous system of infected
individuals contain Ichthyophonus sp-ores with the brain tissue
being almost completely displaced in advanced cases; no other body
system or organs are affected. Fish that are highly infected
frequently go into convulsive, spiral swimming (similar to fish
infected with whirling disease, Myxosoma cerebraiis), into tetany,
then sink Co the bottom and die (Inslee's observations of infected
.fish held in aquaria). Although this parasite is present on the
station, it has posed no serious problems to the survival of the
infected species or to other fish culture operations. Control of
this parasitic organism is difficult due to a lack of knowledge of
its life cycle and exact mode of infection and the "hardiness" of
the spores which most likely withstand dessication.
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