| Gila
Chub |
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Gila
Chub (Gila intermedia)
By Clint D. Adams, Nongame Biologist |
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Scientific
Name:
Gila intermedia. Gila refers to the river basin from which this fish was
first described. The specific epithet is from the Latin roots inter and
medi, which mean middle or between. |
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Description:
Body chunky. Scales large and thick. Coloration dark overall, sometimes
lighter underneath. Adult females larger than males; the former reach
lengths of 10 inches, the latter are rarely larger than 6 inches. Males
in breeding color are orange-red on the belly and sides, with yellow
on the cheeks, lips, and paired fins of larger fish. |
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Habitat:
Adults often associated with cienegas and deep pools in smaller headwater
streams where cover is abundant. Juveniles occur among plants and debris
in shallows and currents, becoming more restricted to pools as they
reach maturity. |
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Distribution:
Historically, the Gila chub was found in most headwater streams of the
Gila River drainage in Arizona and New Mexico, and within the Santa
Cruz and San Pedro river systems of Arizona and Sonora, Mexico. Currently,
it is thought to be extirpated from New Mexico. In Sonora, it was recently
found in two cienegas near the headwaters of the San Pedro River. In
Arizona, populations have been extirpated from Monkey Spring; Arnette,
Cave, Fish, and Queen creeks; San Simon, San Pedro, and Santa Cruz
rivers; and Post Canyon. The largest remaining U.S. populations are
in southeastern Arizona. |
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Biology:
A secretive fish, the Gila chub spends most daylight hours under cover
such as cutbanks and thick overhanging or aquatic vegetation. Gila
chubs reach sexual maturity anywhere from the end of their first year
through their third. Most populations breed primarily from late spring
to summer, depending on conditions, but this species has been known
to breed from late winter through autumn. During breeding, larger females
can be seen cruising deep pools over beds of aquatic plants, followed
by several smaller males.
Gila chubs are opportunistic omnivores, consuming terrestrial and aquatic
insects, as well as smaller fish and filamentous algae. Although some studies
indicate these fish are crepuscular (active mainly in twilight hours),
others suggest most foraging occurs at night. |
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Status:
The Department included the Gila chub on its list of Threatened Native
Wildlife in Arizona (1988), as a threatened species. Gila chub were listed as endangered in 2005. |
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Management
Needs:
Further study of Gila chub life history is needed, as is a plan to prevent
further loss of habitat, re-establish populations in their former range,
and provide for managing this species along with sportfish (most of which
occupy different habitats). Of prime importance is preservation of the
few remaining streams containing Gila chubs. In areas that have been modified,
steps should be taken to restore aquatic habitat. To reduce impacts from
non-native fish, barriers might be built or enhanced to prevent invasions
from downstream. |
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