Life history and ecology of the humpback chub gila cypha in the little colorado and colorado rivers of the grand canyon usa

Kaeding, L.R.; Zimmerman, M.A.; Kaeding, L.R; Zimmerman, M.A

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Life history and ecology of the humpback chub gila cypha in the little colorado and colorado rivers of the grand canyon usa

Kaeding, L.R.; Zimmerman, M.A.

Transactions of the American Fisheries Society 112(5): 577-594

1983

ISSN/ISBN: 0002-8487

Accession: 005807920

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Summary

G. cypha in the Little Colorado River [LCR], a warm saline tributary to the Colorado River [CR], grew rapidly to about 250-300 mm total length at 3 yr of age, the onset of reproductive maturity for female fish. Fish spawned in April or May; annual reproductive success was greatest when spawning coincided with seasonal river runoff. Meristic characters of humpback chubs from the upper 8 km of the river differed from those of fish from the adjacent lower 5-km river reach, and suggested that some genes of bonytail G. elegans may occur in the latter population. Use of the physical habitat by age-0 and juvenile humpback chubs was affected by light intensity; shallow littoral areas were used during darkness, but during daylight only when the water was turbid. No evidence of humpback chub reproduction was found in the CR part of the study area; small humpback chubs collected there resulted from spawning in the LCR Year-round low temperatures in the CR (the tailwater of Glen Canyon Dam) did not inhibit seasonal gonadal maturation of humpback chubs; laboratory studies have indicated that such low temperatures result in nearly complete mortality of embryonic and larval humpback chubs. The recapture of tagged fish, seasonal changes in rates of capture of adults from the LCR, and the distribution of adult humpback chubs in the CR near its confluence with the LCR supported the hypothesis that some adult fish from the CR enter the LCR to spawn. Stomach contents from humpback chubs were dominated numerically by immature Chironomidae and Simuliidae. Lernaea cyprinacea was the most conspicuous metazoan parasite of humpback chubs in the LCR, but was rarely found on fish in the CR. Persistence of the humpback chub in the LCR could be attributable, in part, to the unsuitability of that environment, and that of the CR, for potential competitor or predator species in the drainage. Introduction to the LCR of such a species that might prosper under the physicochemical conditions of the river could have a devastating effect on the humpback chub in the Grand Canyon.

Life history and ecology of the humpback chub gila cypha in the little colorado and colorado rivers of the grand canyon usa

Kaeding, L.R.; Zimmerman, M.A.

Transactions of the American Fisheries Society 112(5): 577-594

1983

Full-Text Article emailed within 1 workday

Summary

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