| Captive
breeding of loach minnow, a threatened species
in Arizona |
| |
 Background:
Loach minnow is a small secretive fish that is native to the Gila River
Basin in Arizona, New Mexico, and Sonora, Mexico. Historically, the
species was locally abundant, but populations have declined drastically
in recent years, and the species is now restricted to sparse tributary
populations in Arizona and New Mexico. The species is listed as threatened
by the U.S. Fish and Wildlife Service and is listed as a species of
special concern in Arizona and New Mexico. Development of captive propagation
techniques for loach minnow has been proposed as a means to facilitate
species recovery. The Research Branch began a study in 2002 to induce
adult loach minnow to spawn in the laboratory, and to develop and document
conditions necessary for incubation and hatching of their eggs, as
well as the rearing of larvae, juveniles, and adults.
Location:
Loach minnow were collected from Aravaipa Creek, Arizona, in the fall of
2002. Fish were captured by seining riffles, and fish were transported
by hatchery truck to Bubbling Ponds Hatchery, near Cornville, Arizona.
Fish are being held indoors in recirculating aquaria, where water temperature
is controlled by room temperature, and an electronic timer and full-spectrum
fluorescent light fixtures control lighting.
Approach:
 Spawning
in raceways is elicited by manipulation of
water temperature and photoperiod to mimic
conditions associated with natural spawning
of wild fish. In the laboratory, day length
is set to mimic April by means of an electronic
timer, and loach minnow are held in raceways
at an ambient room temperature of 21 C. Flow
velocities are approximately 10 cm/sec through
the recirculating system. Spawning substrate
consists of small cobbles and broken pieces
of clay pots. Fish are fed twice daily with
a combination of commercial flake food and
freeze-dried bloodworms.
Eggs are collected twice each day to protect them from cannibalism by adults,
and are incubated at 21 C. The eggs hatch after about 1- 4 days, and larval
fish are quickly moved to holding aquaria, where they are provided starter
foods, such as live brine shrimp and commercial larval fish diets. As fish
grow, food size is increased slowly for about 4 weeks, until the fish are
large enough to ingest commercial flake foods and freeze-dried bloodworms.
Fish tanks must be kept clean, and fish must be monitored daily for signs
of disease. Future research will include hormone injections to induce spawning,
and controlled breeding experiments to determine optimal male:female ratios
among spawning adults. The final report for this project is due September
30, 2004.
Benefits:
The ultimate goal of this study is to provide hatcheries with the techniques
necessary to maintain loach minnow broodstock, and the ability to produce
progeny for future restocking into the wild. This will help meet the goals
of the loach minnow Recovery Plan.
For more information
contact:
Mike Childs, Arizona Game and Fish Department, 1600 North Page Springs
Road, Cornville, AZ 86325.
Phone: (928) 639-1346. E-mail: mike@sedona.net |
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