March 1995 Notes 107

HAFNER,J. C., AND M. S. HAFNER. 1983. Evolu- WILLIAMS,D. F. 1978. Karyological affinities of the tionary relationships of heteromyid rodents. Great species groups of silky pocket mice (Rodentia, Het- Basin Nat. Mem., 7:3-29. eromyidae). J. Mamm., 59:599-612. HENNIG, W. 1965. Phylogenetic systematics. Ann. WILLIAMS, D. F., H. H. GENOWAYS,AND J. K. BRAUN. Rev. Entomol., 10:97-116. 1993. . Pp. 38-196, in Biology of the HOMAN,J. A., AND H. H. GENOWAYS.1978. An Heteromyidae (H. H. Genoways and J. H. Brown, analysis of hair structure among heteromyid ro- eds). Amer. Soc. Mamm., Spec. Publ., 10:1-719. dents. J. Mamm., 59:740-760. WOOD, A. E. 1935. Evolution and relationships of RYAN,J. M. 1989. Comparative myology and phy- the heteromyid rodents with new forms from the logenetic systematics of the Heteromyidae (Mam- Tertiary of western North America. Ann. Carnegie malia, Rodentia). Misc. Publ. Mus. Zool., Univ. Mus. Nat. Hist., 24:73-262. Michigan, 176:1-103. WOOD,A. E., ANDR. W. WILSON. 1936. A suggested STANGL,F. B., JR., AND E. M. JONES. 1987. An nomenclature for the cusps of the cheek teeth of assessment of geographic and seasonal biases in sys- rodents. J. Paleontol., 10:399-391. tematic mammal collections from two uni- versities. Texas J. Sci., 39:129-137.

REPRODUCTIVE BIOLOGY OF THE CHUB, PANDORA (TELEOSTOMI: ), IN A MONTANE STREAM, NEW MEXICO

JOHN N. RINNE

United States Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, The Southwest Forest Science Complex, 2500 South Pineknoll Drive, Flagstaf, AZ 86001

The , Gila pandora, was first purpose of this paper is 1) to report the results reported and described from the Sangre de Cristo of analyses of these data and 2) compare it to Pass in the headwaters of the Rio Grande basin, similar data for congeners. New Mexico (Cope, 1872). It commonly inhabits The Rio de las Vacas is a montane stream pools in streams cool enough for trout, and often (elevation ca. 2,800 m) located on the Santa Fe uses undercut banks and brush for cover. Koster National Forest, Sandoval County, about 120 km (1957) reported that spawning occurs in "late NNW of Albuquerque, New Mexico (Fig. 1). spring," with neither nest construction nor egg Detailed descriptions of this riparian-stream area care evident. Gila pandora is reported as a bait are given in Rinne (1988) and Szaro and Rinne (Miller, 1952) or forage , but Koster (1957) (1988) and are summarized here. This third-or- suggested it might potentially compete with trout. der stream is affected by typical United States It has been suggested that the Rio Grande chub Forest Service multiple-use management activi- is becoming rare in the Pecos basin (Minckley, ties, including logging, recreation, road building, 1980). Sublette et al. (1990) described popula- and livestock grazing. The portions of the study tions in New Mexico as stable and reproducing area that have been fenced to exclude grazing throughout most of their historic range. The Rio Grande chub was encountered in large have more abundant shrubby riparian vegetation, numbers during research on grazing effects on such as willow (Salix sp.) and alder (Alnus sp.) stream habitat and biota in an upper elevation than grazed regions. Beaver (Castor canadense) (>2,500 m) montane stream (Rio de las Vacas) inhabit the area, and while damming of the stream in northern New Mexico (Rinne, 1988). Because is common, it is not permanent because of annual ecological and life history information on the spe- washouts by spring runoff. Streambanks are un- cies is sparse, specimens of chub were retained stable in the grazed areas and fine sediment con- and preserved during 1985 to 1987 to define se- tent of the stream substrate is greater in reaches lected aspects of its reproductive biology. The subjected to grazing (Rinne, 1988). 108 The Southwestern Naturalist vol. 40, no. 1

N TABLE1-Comparison of reproductive traits of male Cuba and female Rio Grande chub (Gila pandora) in the Rio

24 km de las Vacas, 1985-1987. Values are means (±SE). All comparisons are significantly different (P < 0.01). Cuba

Study Male Female Section Trait n = 79 n = 105 Total length (mm)1 109.70 ± 1.6 117.50 ± 2.5 Albuquerque Fish volume (ml) 15.80 ± 0.69 21.80 + 1.4 Gonad (ml) 0.38 ± 0.03 1.16 ± 0.11 Color index 1.30 ± 0.05 1.50 ± 0.05 Gonadal index 2.15 ± 0.18 4.84 ± 0.39 Range in total length = 67-140 mm in males, 52- 181 mm in females.

dant (n = 105) than males (n = 79). Female chub averaged significantly greater in both length and 1 km volume (t-test, P = 0.01) than males (Table 1). FLOW As is common in cyprinids, the presence of color FIG.1-Location of the Rio de las Vacasin northern and its intensity was also significantly (P < 0.001) New Mexico. Sample areas are indicatedby shading. more common in males than in females. Multiple regression of color in chubs showed this trait re- In 1985, Rio Grande chub were collected dur- lated significantly (P < 0.01) to size and month ing regularly scheduled summer (June and July) of collection. However, the regression model ex- sampling, with additional samples taken in plained only about 25% of the variation in color March, April, September, and October 1985 to of chubs. By comparison, logistic regression pro- 1987. Specimens were immobilized with a DC, duced a "best fit" model that included sex, month, backpack electrofishing device, captured with and gonad volume. The remaining two indepen- dipnets and immediately preserved in a 10% for- dent variables, fish volume and length, were not malin-sugar solution to retain coloration. The significantly (P = 0.28 and 0.43) related to color. total lengths (TL) of preserved specimens were The fitted model for chubs in the Vacas is: E(the measured, and fish volumes were estimated by logit) = -3.0788 - 1.1176(sex) + .3480(month) liquid displacement. Gonads were then removed + 1.4264(gonad volume), where the probability and their volumes similarly determined by liquid of no color = expected E/(1 + expected E). This displacement. Fecundity was estimated by re- model predicted the correct outcome 73.9% of the moving ovaries and counting ova present in a sub- time (136 of 184 specimens). sample of 20 females collected in March and June Difference in tuberculation on the body and 1985 with gonadal indices (see below) of 4.0 or fins of male versus female chubs was not as marked greater. as was coloration (Table 2). Tubercles were more Presence and intensity of tuberculation and pronounced on the caudal peduncle of males than breeding coloration on the body (1 = present; 2 females and extremely more pronounced on the = absent) and fins were noted relative to sex. anal and caudal fins of males. Variation in tuberculation was coded from 1 to As in most , GI was significantly greater 3 to delineate pronounced presence (1), weak (P < 0.001) in females than in males (Table 1). presence (2) or absence (3). Gonadal indices (GI) ANOVA indicated significant differences (P = were calculated by dividing gonadal volume by 0.001) in gonadal indices among sample dates for fish volume and multiplying the resulting value both males and females (Table 3). If one uses by 100. Data were analyzed by t-tests, analysis higher indices (>5.0) as an indicatoin of matu- of variance (ANOVA), and logistic regression. rity, chubs reach maturity at about 90 mm, TL Of the 184 Rio Grande chubs collected for (Fig. 2). Fecundity of the subsample of 20 female reproductive analyses, females were more abun- chubs ranged from 1,366 to 6,322 ova, and av- March 1995 Notes 109

TABLE2-Comparison of degree of tuberculation on TABLE 3-Comparison of mean seasonal gonadal body and fins of male and female Rio Grande chub indices of Rio Grande chubs (Gila pandora) in the Rio (Gilapandora) in the Rio de las Vacas, New Mexico, de las Vacas, New Mexico, 1985 to 1987. Multiple 1985-1987. All values are means ± SE. * = P < 0.05; range test groupings of sample periods are indicated ** = P < 0.01. by alphabetical denotation.

Male Female Male Female Sample n = 79 n = 105 Tuberculation date n X + SE n X + SE Body 2.9 ± 0.03 3.0 March' 7 3.20 ± 0.43c 5 5.40 ± 1.17e Head 2.9 ± 0.03 3.0 April 3 2.33 ± 1.18b 5 3.30 ± 1.73c Caudal peduncle 2.4 ± 0.10* 2.6 ± 0.07* June 26 2.58 ± 0.25c 36 7.43 ± 0.87f Gular 3.0 3.0 June 16 0.65 ± 0.19a 24 2.46 ± 0.366 Operculum 3.0 3.0 July 0.28a Pectoralfin 3.0 3.0 6 1.49 ± 1.00b 5 2.44 ± Sept 8 3.56 ± 0.59c 16 4.04 ± 0.39d Pelvic fin 3.0 3.0 Oct 13 1.92 ± 0.41b 14 4.34 ± 0.44e Anal fin 2.0 ± 0.09** 2.3 ± 0.01** Caudal fin 3.0 ± 0.02* 3.0* 1 All samples made in 1985 except for the second sample listed for June and the sample for September, which were made in 1987. eraged 3,362 + 366 (SE) ova. Regression anal- yses indicated only 10% of the variation in fe- , G. robusta grahami described by cundity of chubs was explainable by gonad volume. Rinne (1976), as spawning from January to In contrast to Koster's (1957) observation that March in Fossil Creek, Arizona which was in- the Rio Grande chub spawned only in spring, fluenced by a thermal spring. Fecundity of the chubs displayed an apparent bimodal spawning roundtail chub in Fossil Creek (1,000-4,000 total pattern in the Rio de las Vacas (Table 3). As- ova per female) was similar to the range of fe- suming that a mean GI greater than 5.0 and color cundity estimated for Rio Grande chub in the Rio presence and intensity indicate reproductive ac- de las Vacas. Based on appearance of young in tivity, chubs have an extended spawning peak in collections, reproduction is listed as spring and spring (March to June) followed by a briefer, early summer for both the Yaqui (Gila purpurea) less marked autumnal (mean GI > 4.0; Septem- and Sonora (Gila ditaenia) chubs (Minckley, ber to October) spawning event. Alternatively, 1973). Cross (1978) reported enlargement of tes- the GI peak in Autumn may represent egg de- tes of Virgin River roundtail chubs (Gila r. sem- velopment for the following spring's spawning. inuda) in March. The main discrepancy which contradicts this bimodal pattern was mean GI development in June 1985 versus June 1987. The lower mean 20 GI in both males and females in the temporally asynchronous sample in June 1987 compared to 16 June 1985 is attributable to less volume and per- sistence of spring runoff in 1987. Conceivably, INDEX12 the chub both commenced and terminated spawn- ing earlier relative to streamflow in 1987. Fur- 8 ther, very low flow conditions in June 1987 re- GONADAL pressed mean gonadal development to low values 4 in both males and females compared to June 1985. Little information is available in the published 0 literature on the reproductive biology of chubs of 50 80 110 140 170 200 the genus Gila in the southwest. Vanicek and TOTAL LENGTHIN MILLIMETERS in Kramer (1969) reported that roundtail chub FIG. 2-Regression of gonad index on total length the mainstream Green River spawned in spring of female chubs to delimit probable size at maturity. with rising water temperature and receding flows. Dashed lines are 95% confidence limits of means for Using gonadosomatic index (gonad weight/body both fitted (lower two) and predicted (upper) regres- weight), Neve (1976) reported a subspecies of sion lines. 110 The Southwestern Naturalist vol. 40, no. 1

Neve (1976) reported that male roundtail chubs McNATT, R. M. 1974. Re-evaluation of the native in Fossil Spring, Arizona, developed small white fishes of the Rio Yaqui in the Unites States. Proc. tubercles and an orange tinge at the base of the Ann. Conf. Western Assoc. Game and Fish Comm., fins. Female chubs in Fossil Creek also developed 54:273-279. MILLER,R. R. 1945. A new cyprinid fish from south- "minor" tuberculation in the head region. Rinne ern Arizona, and Sonora, Mexico, with the descrip- and Minckley (1970) list reddening on the fin tion of a new subgenus of Gila and a review of bases, jowls, and the lower body of male Gila related species. Copeia, 1945:104-110. chub (Gila intermedia). Coloration on the fins and -. 1952. Bait fishes of the lower Colorado River body of other Gila has been described by Minck- from Lake Mead, Nevada, to Yuma, Arizona, with ley (1973). Miller (1945) noted and described a key for their identification. California Fish and breeding coloration of types of . The Game, 38:7-42. axils of the pectoral and pelvic fins and the base MINCKLEY,W. L. 1973. Fishes of Arizona. Arizona of the anal fin were described as brilliant Chinese Game and Fish Dept., Phoenix. red. The brightest fish were orange on the sides 1980. Rio Grande chub. Pp. 170, in Atlas of North American freshwater fishes (D. S. Lee et of the belly between the bases of the paired fins, al., eds.). North Carolina State Museum, Raleigh. and although sexes were not separated, the NEVE, L. C. 1976. The life history of the roundtail brightest fish were obviously males. Similarly, chub, Gila robustagrahami, at Fossil Creek, Arizona. coloration in the Rio Grande chub in the Rio de Unpubl. M.S. thesis, Northern Arizona Univ., las Vacas was present in both sexes, but was Flagstaff. significantly more common in males than in fe- RINNE,J. N. 1976. Cyprinid fishes of the genus Gila males (Table 1). McNatt (1974) reported pre- from the lower Colorado River Basin. Wassman J. breeding male Yaqui chub (Gila purpurea) as of Biol., 34:65-107. "steely blue" in color and females as straw-yel- 1988. Grazing effects on stream habitat and low. Coloration was reported to be very intense fishes: research design considerations. North Amer. in the undescribed, now-extinct Monkey Springs J. Fish. Mgmt., 8:240-247. RINNE, J. N., AND W. L. MINCKLEY. 1970. Native chub (Gila sp.). Arizona fishes: Part III: "Chubs." Arizona Wildl. Views, 17:12-19. LITERATURECITED SUBLETTE, J. E., M. D. HATCH, AND M. SUBLETTE. COPE,E. D. 1872. Report on the recent reptiles and 1990. The fishes of New Mexico. Univ. New Mex- fishes of the survey collected by Campbell, Car- ico Press, Albuquerque. rington, and C. B. Dawes. Preliminary report of SZARO,R. C., AND J. N. RINNE. 1988. Ecosystem the U.S. Geological Survey of Territories, 1872. approach to management of southwestern riparian U.S. Geological Survey, Washington, D.C. communities. Trans. 53rd N. Amer. Wildl. and CROss, J. N. 1978. Status and ecology of the Virgin Nat. Res. Conf., 53:502-511. River roundtail chub, Gila robusta seminuda (Os- VANICEK,C. D., AND R. H. KRAMER. 1969. Life teichthys: ). Southwestern Nat., 23:519- history of the Colorado Squawfish, Ptychocheilus 528. lucius, and the Colorado chub, Gila robusta, in the KOSTER,W. J. 1957. Guide to the fishes of New Green River in Dinosaur National Monument. Mexico. Univ. New Mexico Press, Albuquerque. 1964-1966. Trans. Amer. Fish. Soc., 98:193-208.