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<br />6
<br />
<br />and 2740) one specimen 267 mm SL (no. 2732) has only
<br />small granular ova. The other four females with stan-
<br />dard lengths of 283, 292, 297, and 305 mm have two size
<br />groups of ova. Ten ova of the larger size group from
<br />female no. 2734 measured, 1.3, (4) lA, (3) 1.5 and
<br />(2) 1.6 mm in diameter. Ten ova from female no. 2736
<br />measured (4) lA, (5) 1.5 and 1.6 mm in diameter. The
<br />smaller size group of ova in female no. 2735 measured
<br />(4) 1.0, (5) l.l, 1.2 mm in diameter. This female had
<br />no tubercles anywhere on the body or the fins. Female
<br />no. 2740 is 305 mm in SL and is the only female of the
<br />five that has tuberculate ridges developed on the scales
<br />of the breast patches. Ten of the larger ova measured
<br />1.6, 1.7, 1.8, 1.9, (2) 2.0, (3) 2.1 and 2.2 mm in diameter.
<br />Six ova of the smaller size group measured 0.9, (2) l.l,
<br />(2) 1.2, and 1.3 mm in diameter. The smaller ova ap-
<br />peared to be very pale whereas the larger ova were
<br />yellowish. We believe this female was probably ripe at
<br />the time of capture.
<br />
<br />Ten ova were removed from the 320 mm SL female
<br />(TU 100542) and these measured 1.3, lA, (5) 1.5 and
<br />(3) 1.6 mm in diameter.
<br />
<br />We have no measurements of fresh, non-preserved ova,
<br />thus all our measurements above reflect the shrinkage
<br />that takes place as a result of preservation.
<br />
<br />Spawning probably occurs during June and July in
<br />the Grand Canyon area. We presume that the 24;6 and
<br />the two 24.7 mm inSL individuals taken on 22 Septem-
<br />ber represent young-of-the-year.
<br />
<br />The future of the humpback chub population in the
<br />Grand Canyon area is questionable. Perhaps a coldwater
<br />strain may persist in the vicinity of the Little Colorado
<br />River. The extreme man-manipulated flow patterns of
<br />the main Colorado River can only be viewed as detri-
<br />mental to the survival of the species. During average to
<br />maximum releases from Glen Canyon Dam the volume
<br />of extremely cold water is too great for the Little Colo-
<br />rado River water to have much warming effect. If ex-
<br />tremelow flows are going to be maintained during the
<br />summer of 1977 (spawning time), this may have a tem-
<br />porary benefit in that the warmer Little Colorado River
<br />water will elevate more extensively the temperature in
<br />the main Colorado River. Undoubtedly the lower Little
<br />Colorado River is the major spawning area for the sur-
<br />viving population. We collected and released a single
<br />adult Gila cYPha at the mouth of Shinumo Creek. Dur-
<br />in?" all of our sampling at Shinumo a total of three young
<br />Gzla cYPha were taken, therefore we assume this area to
<br />be marginal as a spawning site primarily because of its
<br />small size.
<br />
<br />Material Examined
<br />
<br />Precise collection sites for Powell Reservoir specimens
<br />of Gila CYPha are not known; some came from Kane
<br />County, Utah, and some from Coconino County, Ari-
<br />zona. All Grand Canyon specimens were taken in Coco-
<br />nino County, Arizona.
<br />
<br />TULANE UNIVERSITY MUSEUM NATURAL HISTORY
<br />
<br />Powell Reservoir: National Fish and Wildlife Labora-
<br />tory (NFWL) (metal field tag nos. 2732, 2734, 2735,
<br />2736, 2737, 2738, 2739, 2740, 2741), TU 100542. Colo-
<br />rado River just below Glen Canyon Dam: National Fish
<br />and Wildlife Laboratory (metal field tag nos. 2761, 2762,
<br />2763, 2768, 2769, 2770, 2771). Colorado River at Lee's
<br />Ferry, River Mile 0: Museum of Northern Arizona,
<br />MNA Z5.29. Colorado River, River Mile 31.5: MNA
<br />Z5.30. Colorado River, River Mile 31.9: MNA Z5.31
<br />and MNA Z5.32. Colorado River at River Mile 44: TU
<br />92785. Mouth of Little Colorado River, River Mile 61.5:
<br />TU 78682, 89793, 95166, 95767, 97592, 97918, 97966,
<br />99078. Colorado River, River Mile 66: TU 99081. Colo-
<br />rado River, River Mile 71: TU 95777, 97921, 97967,
<br />99086. Mouth of Shinumo Creek, River Mile 108.7: TU
<br />95784, 99092. Green River at town of Green River,
<br />Grand Co., Utah: TU 99151.
<br />
<br />Acknowledgments
<br />
<br />We particularly would like to thank the Federal En-
<br />dangered Species Office for issuing the senior author
<br />permit no. PRT8-185-C, and Amendment No. I to per-
<br />mit no. PRT8-185-C which enabled us to collect and
<br />study the unique form, Gila cypha. Also we extend our
<br />appreciation to Robert A. Jantzen, Arizona Game and
<br />Fish Department; Dean Spackman, Utah Division of
<br />Wildlife Resources; Merle E. Stitts, Grand Canyon Na-
<br />tional Park and Joe L. Kennedy, Glen Canyon National
<br />Recreation Area for the issuance of collecting permits
<br />and for their cooperation. We thank Joe Kennedy for
<br />the two salvage specimens from Powell Reservoir, and
<br />we thank Steve Carothers for the loan of four specimens
<br />housed at the Museum of Northern Arizona. Special ac-
<br />knowledgment is c!jue Clyde Jones and Robert Finley for
<br />making available ~he specimens housed at the National
<br />Fish and Wildlife I Laboratory in Ft. Collins, Colorado.
<br />We wish to acknotledge the help' of Scott Thybony for
<br />bringing our atten~tion to the article by the Kolb broth-
<br />ers. We also exten our deep appreciation to those who
<br />helped us collect the material, namely: Lyn Branch,
<br />Cindy Deacon, James Deacon, Robert Fisher, Jim Hall,
<br />Clyde Jones, Lindtl Loetterle, Margaret Mathews, Dawn
<br />Remington, C. Ro ert Shoop, Jayson Suttkus, and James
<br />Williams. Jeanne uttkus did the photographic work of
<br />specimens for whic we are most appreciative. The cover
<br />photograph of the mouth of 'the Little Colorado River
<br />was contributed by Robert Esher. Wilma Martin did the
<br />final drafting and photographing of the scattergrams.
<br />This study was in part supported by National Park Ser-
<br />vice Contract number CX821060006.
<br />
<br />Literature Cited
<br />
<br />Gaufin, A. R., C. R. Smith and P. Dotson. 1960. Aquatic survey of
<br />the Green River and tributaries with the Flaming Gorge basin.
<br />In: Ecological studies of the flora and fauna of Flaming Gorge
<br />Reservoir basin, Utah and Wyoming. C. E. Dibble, ed., Uriiv.
<br />Utah Anthropol. Pap. (48): 139-162.
<br />Holden, P. B. and C. B. Stalnaker. 1970. Systematic studies of the
<br />cyprinid genus Gila, in the Upper Colorado River Basin. Copeia.
<br />1970 (3) : 409-420.
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