9668

• UCREFRP Catalog Number: 9668
• Author: Crowl, T. A. and e. al.
• Title: Bonytail Draft 1998 Annual Report, February 2000.
• USFW Year: 2000.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

breeding season, in mid June to early July, bright red-orange lateral slashes between
the paired fins, small tubercles on the head and anterior portions of the body develop
on males. Breeding colors are less defined and the tubercles less developed in
females (USFWS 1990). The optimal spawning temperature for bonytail is probably
near 20°C (Hamman 1982). Females produce between 1,000 and 17,000 eggs which
adhere to rocks or settle in depressions. No parental care is given to the eggs once
they are deposited. Eggs begin hatching about 9 hours after fertilization, and swim-up
occurs 48-120 hours later. Marsh (1985) noted that newly hatched bonytail had the
highest larval survival at temperature of 15 and 20°C (32%) with no survival at 5, 10,
and 30°C. Survival rate of juveniles is 17-38%
In general, adult Gila spp. feed on terrestrial insects, plant debris, and, filamentous
algae. Likewise, juvenile Gila spp. tend to eat Chironomidae larvae and
Ephemeroptera nymphs (Vanicek and Kramer 1969).
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