7017

• UCREFRP Catalog Number: 7017
• Author: Starnes, W. C.
• Title: Colorado River Basin
• USFW Year: 1989.
• Copyright Material: NO

Reiterates the difficulties of distinguishing between young
of three main river Gila species as well as hybrids or
"variants". Presents data on nuchal hump ratios from
specimens collected in areas of the upper Colorado River.
Implies that all specimens from uppermost (Debeque) canyon
are cvpha X robusta intergrades as related in Valdez et al.
(1982)(next).
1982. Valdez, R., P. Mangan, R. Smith, and B. Nilson. Upper
Colorado River investigation (Rifle, Colorado to Lake
Powell, Utah); pp. 101-279, in: W.H. Miller et al., eds.,
Colorado River fishery project. U.S. Fish & Wldlf. Serv.-
Bur. Reclam., Salt Lake City, Utah. 365 p.
Reiterates the difficulties in applying the criteria for
separation of Gila spp. suggested by Smith et al.
(1979)(e.g., nuchal hump ratio) in field studies. Also
reiterates difficulties in determination of young specimens
and the considerable number intermediate specimens
encountered in the reach of the Colorado examined which are
deemed to be G. cypha X G. robusta hybrids resulting from
habitat alteration.
1983. Behnke, R.J., and D.E. Benson. Endangered and threatened
fishes of the upper Colorado River Basin (revised version).
Coop. Ext. Serv. Colo. St. Univ. Bull. 503A. 34 p.
Illustrates and gives distinguishing features for G. cypha
and G. elegans.
1983. Kaeding, L.R., and M.A. Zimmerman. Life history and
ecology of the humpback chub in the Little Colorado and
Colorado rivers of the Grand Canyon. Tran. Amer. Fish. Soc.
112:577-594.
Essentially the same as Kaeding and Zimmerman (1982) above.
1983. Rosenfeld, M.J. The use of chromosomes in fisheries
biology: population species discrimination in chubs (genus
Gila). Proc. Bonnevl. Chap. Amer. Fish. Soc. 1983: 9-17.
(Not seen). Presumably includes information contained in
unpublished manuscripts of Rosenfeld (below).
1983. Smith, G.R. Significance of hybridization in Chasmistes
and Gila. Trans. Bonnevl. Chap. Amer. Fish Soc. 1983:1-8.
Draws a parallel between supposed mass hybridization between
sucker species in Utah lake and the situation with Gila spp.
in the upper Colorado River system speculating that
15