Culture of Roundtail Chub, Gila robusta robusta (Cyprinidae), through the Larval Period
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Resource Abstract:
The cyprinid genus Gila includes three historically sympatric species endemic to the Colorado River Drainage, i.e., G. robusta
(roundtail chub), G. cypha (humpback chub) and G. elegans (bonytail). Roundtail chub are locally common and widely distributed
throughout the Colorado River System, whereas humpback chub and bonytail are presently rare and have extremely restricted
distributions (Behnke and Benson, Coop. Ext. Serv. Bull. 503A, Colorado State Univ., 1983; Lee et al., Atlas of North American
freshwater fishes, North Carolina State Mus. Nat. Hist., Raleigh, 1980; Tyus et al., pp. 12-70 in Fishes of the Upper Colorado
River System: present and future [W. H. Miller, H. M. Tyus, and C. A. Carlson, eds.], Am. Fish. Soc., Bethesda, Maryland,
1982; Rinne, Wasmann J. Biol., 34:65-107, 1976). The humpback chub and bonytail are listed as endangered by several western
states (Behnre and Benson, 1983; Deacon et al., Fisheries, 4:29-44, 1979) and by the United States Department of the Interior
(Federal Register, United States Fish Wildl. Serv., Washington, D.C., Part II, 45:33768-33781,1980). These three species are
closely related, systematically and ecologically, and problems exist over their identification and classification. To complicate
matters, intergrades or hybrids of these species might occur naturally (Holden and Stalnaker, Copeia, 1970:409-420, 1970;
Smith et al., pp. 613-623 in Proceedings of the first conference on scientific research in national parks [R. M. Linn, ed.],
Dep. Inter., Trans. Proc. Ser. 5, 1979). Several investigators studied the systematics of adult and immature roundtail chub,
humpback chub and bonytail (Holden and Stalnaker, 1970; Smith et al., 1979; Suttkus and Clemmer, Tulane Univ., Mus. Nat. Hist.,
Occas. Pap. 1, 1977); however, no comparable studies were completed for their larvae and early juveniles. Comparative taxonomic
research is being conducted on the early life-history stages of these species by the Colorado Division of Wildlife and the
Larval Fish Laboratory, Colorado State University, Fort Collins. Pursuant to the goals of this research, we acquired known-age
developmental series of humpback chub, bonytail and six Gila hybrid crosses (Hamman, Prog. Fish-Cult., 43:140-141, 1981; Hamman,
Prog. Fish-Cult., 44:201-203, 1982a; Hamman, Prog. Fish-Cult., 44:213-216, 1982b) from Willow Beach (Arizona) National Fish
Hatchery; unfortunately, a similar roundtail chub series was not available. The objective of the present study was to obtain
viable roundtail chub gametes from "genetically pure" wild brood stock and use conventional culture techniques to produce
a laboratory-reared developmental series. Results of the first successful culture of roundtail chub are presented. Published
in The Southwestern Naturalist, volume 30, issue 1, on pages 152 - 154, in 1985.
Citation
Title Culture of Roundtail Chub, Gila robusta robusta (Cyprinidae), through the Larval Period