June 1995 Notes 237

PLUMMER,M. V. 1992. Relationships among moth- ards; resolution of a paradox. Amer. Nat., 112:595- ers, litters, and neonates in diamondback water 608. snakes (Nerodia rhombifer). Copeia, 1992:1096- WERNER,D. I. 1988. The effect of varying water 1098. potential on body weight, yolk and fat bodies in RAND, A. S. 1984. Clutch size in Iguana iguana in neonate green iguanas. Copeia, 1988:406-11. Central Panama. Pp. 115-122, in Vertebrate ecol- 1991. The rational use of green iguanas. ogy and systematics-a tribute to Henry S. Fitch Pp. 181-201, in Neotropical wildlife use and con- (R. A. Seigel, L., E. Hunt, J. L. Knight, L. Ma- servation (J. G. Robinson and K. H. Redford, eds.). laret, and N. L. Zuschlag, eds.). Mus. Nat. Hist., Univ. Chicago Press, Chicago, Illinois. Univ. Kansas, Lawrence. WERNER,D. I., ANDT. J. MILLER. 1984. Artificial RAND, A. S., AND H. W. GREENE. 1982. Latitude nests for female green iguanas. Herpetol. Rev., 15: and climate in the phenology of reproduction in the 57-58. green iguana, Iguana iguana. Pp. 142-149, in Igua- WIEWANDT,T. A. 1982. Evolution of nesting pat- nas of the world: behavior, ecology and conservation terns in iguanine lizards. Pp. 119-141, in Iguanas (G. M. Burghardt and S. Rand, eds.). Noyes Publ., of the world: behavior, ecology and conservation New Jersey. (G. M. Burghardt and S. Rand, eds.). Noyes Publ., Vitt, L. J. 1978. Caloric content of lizard and snake New Jersey. (Reptilia) eggs and bodies and the conversion of WILLIAMS,G. C. 1966. Adaptation and natural se- weight to caloric data. J. Herpetol., 12:65-72. lection. Princeton Univ. Press, Princeton, New Jer- VITT, L. J., ANDJ. D. CONGDON. 1978. Body shape, sey. reproductive effort, and relative clutch mass in liz-

REPRODUCTIVE BIOLOGY OF THE RIO GRANDE SUCKER, CATOSTOMUS PLEBEIUS (CYPRINIFORMES), 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, Arizona 86001

Although the Rio Grande sucker, Catostomus spawns in spring and, in some areas, in the fall. plebeius, was first described almost a century and Although adults may grow to a large size (>40 a half ago by Baird and Girard (1854), Koster cm), most individuals are small and some mature (1957) first presented the meager known life his- when only "a few inches long." Rausch (1963) tory information for the species. It is currently examined age, growth and maturity of this suck- distributed in tributaries of the Rio Grande, pri- er. Koster (1957) suggested this species to be a marily north of the 36th parallel (Sublette et al., good bait or forage fish and that trout can and 1990). It has been introduced into the headwaters commonly do feed on this largely primary con- of the Gila River. Although substantial popula- sumer. tions are extant in New Mexico, only one occurs The Rio Grande sucker was encountered in in Colorado. The species also currently inhabits large numbers during research investigating the a half dozen river basins encompassing three states effects of grazing on nearstream and instream of Mexico (Smith, 1966; Hendrickson et al., 1980; habitat and biota in the Rio de las Vacas in north- Sublette et al., 1990). ern New Mexico (Rinne, 1988). Because there Larger individuals feed on filamentous algae is a lack of ecological and life history information and other microscopic and macroscopic organisms for Rio Grande sucker, specimens were collected such as diatoms and benthic invertebrates inhab- between 1985 and 1987, preserved, and aspects iting fast, rocky riffles (Sublette et al., 1990). of their reproductive biology were examined. This Koster (1957) reported that Rio Grande sucker paper reports information on aspects of the re- 238 The Southwestern Naturalist vol. 40, no. 2

TABLE1-Comparison of reproductivetraits of male TABLE2-Comparison of degreeof tuberculationon and female Rio Grande sucker (Catostomusplebeius) body and fins of male and female Rio Grande sucker in the Rio de las Vacas, 1985-1987. All values are (Catostomus plebeius) in the Rio de las Vacas, New means (+SE). All comparisonsare significantlydif- Mexico, 1985-1987. All values are means (+SE). ** ferent (P < 0.01). = P < 0.01.

Male Female Male Female Trait n = 112 n = 99 Tuberculation n = 112 n = 99 Total length (mm1) 102.1 + 1.4 110.1 + 2.0 Body 2.7 + 0.05 3.0 Fish volume (ml) 12.7 + 0.54 16.8 + 0.07 Head 2.5 + 0.07** 3.0 + 0.02** Gonad (ml) 0.30 + 0.02 0.82 + 0.09 Caudal peduncle 2.9 + 0.03 3.0 Color index 1.5 + 0.05 1.7 + 0.04 Gular 2.6 + 0.05** 3.0 + 0.01** Gonadal index 2.3 + 0.19 4.6 + 0.34 Operculum 2.6 + 0.07 3.0 Pectoralfin 2.4 + 0.07** 3.0 + 0.02** in mm males, Range total length = 60-138 in 61- Pelvic fin 3.0 3.0 162 mm in females. Anal fin 3.0 3.0 Caudal fin 3.0 3.0 productive biology of the Rio Grande sucker in- habiting the Rio de las Vacas in Northern New Mexico. displacement. Gonadal indices (GI) were calcu- The Rio de las Vacas is a third-order montane lated by dividing gonadal volume by fish volume stream (elevation, 2,800 m) located on the Santa and multiplying the resulting value by 100. Fe- Fe National Forest, Sandoval County, about 120 cundity was estimated by removal of ovaries and km NNW of Albuquerque, New Mexico (Rinne, counting of all mature ova present in 21 females 1988, 1995). Detailed descriptions of this ripar- collected in March, June, and July, 1985 and ian-stream area are given in Rinne (1988) and with GI greater than 4.0. Szaro and Rinne (1988) and are summarized here. Presence and intensity of tuberculation and The stream is affected by typical forest manage- breeding coloration on the body and fins were ment activities such as logging, recreation, road noted relative to sex. Variation in tuberculation building, and livestock grazing. Portions of the was coded from 1 to 3 to delineate either pro- study area have been fenced to exclude livestock nounced presence (1), weak presence (2), or ab- grazing. Riparian vegetation is more abundant sence (3). Color was recorded as either present within these exclosures and is dominated by a (1) or absent (2). willow (Salix)-alder (Alnus) community. Beaver Data on reproductive traits between sexes were (Castorcanadense) inhabit the area, and damming analyzed by simple t-tests. Analysis of variance of the stream is common, however dams are not (ANOVA) was used to compare GI among sam- permanent because of annual washouts by spring ple dates. Length and GI were related by re- runoff. Streambanks are unstable in the grazed gression analyses to depict size at maturity. areas (Rinne, in litt.) and fine sediment content Of the 211 suckers collected for reproductive of the stream substrate is greater in reaches sub- analyses during the period March 1985 through jected to grazing (Rinne, 1988). June 1987, 112 were males and 99 females. Fe- Most Rio Grande suckers were collected dur- male suckers were only slightly but significantly ing annual summer sampling (June to July), with (P = 0.002) larger than males (Table 1). Sexual additional samples taken in March, April, Sep- dimorphism was also illustrated by the signifi- tember, and October 1985. Rio Grande sucker cantly greater mean volume of female than male were stunned with a direct current, backpack suckers (Table 1). electrofisher, dipnetted, and immediately pre- As in most cypriniform fishes, the presence of served in 10% formalin-sugar solution in order color was also significantly more common in males to enhance color retention in specimens. The total than in females (P < 0.001). Regression models length (TL) of preserved specimens was mea- for the sexes explained only about 25% of the sured and fish volume was estimated by liquid variation in color of suckers. By comparison, lo- displacement (ml). Gonads were then removed gistic regression produced a "best fit" model that and their volumes similarly determined by liquid included sex, month, gonad volume, and length. June 1995 Notes 239

TABLE3-Comparison of mean seasonalgonadal indices of Rio Grande suckers(Catostomus plebeius) in the Rio de las Vacas, New Mexico, 1985-1987.

Sample date Male Female March' n = 5 2.12 + 1.43 n = 14 4.26 + 0.32 April n = 3 1.8 + 0.31 n= 83.83 + 0.51 June n = 20 4.07 + 0.43 n = 18 7.80 + 1.12 June n = 13 0.57 + 0.19 n = 20 2.69 + 0.58 July n = 35 3.13 + 0.19 n = 15 5.69 + 1.03 Sept n = 23 0.72 + 0.13 n = 6 3.18 + 0.30 Oct n = 13 2.18 + 0.72 n = 18 3.61 + 0.18 ' All samplesmade in 1985 except for the secondsample listed for June and the samplein September,which were made in 1987.

The remaining independent variable, fish vol- yses indicated 56% of the variation in fecundity ume, was not significantly (P = 0.09) related to of suckers was explained by gonad volume. Fe- color. The fitted model for Rio Grande suckers cundity of suckers varied significantly with season in the Rio de las Vacas is: (P = 0.02) and was greatest in the autumn and least in the spring. E (the logit) = -7.0199 - 0.8614(sex) Koster (1957) previously suggested that the + 0.3829(month) Rio Grande sucker displayed a definite spring to + 0.7869(gonad volume) summer perhaps an autumnal spawn- + 0.0313(length) early and ing effort. This native sucker definitely spawned where the probability of no color is: expected E/1 in the spring and early summer, but an autumnal + expected E. This model predicted color cor- spawn was not evident. Descriptions of timing of rectly 68.7% of the time or in 145 of 211 speci- spawning of other members of the genus Catos- mens. Separation of sexes and similar analyses tomus in the literature are varied. The desert resulted in increased predictability of color for sucker, Catostomus clarki, has been described as females (81 of 99 or 81.8%). spawning in the spring within its geographic range In general, differences in tuberculation on the (Smith, 1966) and late winter to early spring in body and most fins of male versus female suckers Arizona (Minckley, 1973), and in late winter in was not as marked as was coloration (Table 2). the Santa Clara River, Utah (Rinne, 1971). Cross However, the head, gular region, and pectoral (1975) suggested a prolonged period of spawning fins of male suckers contained greatly pronounced (March to June) for the desert sucker in the tuberculation compared to female suckers. Virgin River, Nevada. Although they did not spe- Typical of most cypriniform fishes, GI during cifically observe this, Sigler and Miller (1963) the spawning season were significantly greater (P indicated the flannelmouth sucker, Catostomusla- < 0.001) in female than in male suckers (Table tipinnis, appears to spawn in spring and summer 1). ANOVA indicated significant differences (P in the upper Colorado River. = 0.001) in gonadal indices among sample dates Variability in spawning season of western ca- for both males and females (Table 3). Assuming tostomids may be explained by differences in wa- greater indices indicated increased reproductive ter temperature and stream size, and perhaps activity, Rio Grande suckers displayed a spawn- most importantly, pattern of season or annual ing peak in early summer, (June through July). runoff. Based on annual observations of flows in Gonadal indices were significantly greater in the Rio de las Vacas, the Rio Grande sucker suckers in June 1985 than in June 1987. If one spawned on the waning side of the period of peak uses greater indices (i.e., >4.0) as an indication spring flows. Once normal spring runoff subsided of maturity, suckers reach maturity at about 90 (i.e., late June to early July), spawning quickly mm, TL (Fig. 1). terminated (Table 3). This is further illustrated Fecundity of the 21 female suckers (>100 mm, by the June 1985 and 1987 samples. Time of and GI > 4.0) ranged from 695 to 4,701 ova, sampling in 1985 was June 6. By comparison, and averaged 2,035 + 240 (SE). Regression anal- sampling in 1987 was almost 3 weeks later (June 240 The Southwestern Naturalist vol. 40, no. 2

24). By late June 1987, flows had abated and GI 18 were significantly lower than two years previous. This is attributable to presence of more spent 15 females and males and was also noted for Rio S12 Grande chubs in this same stream (Rinne, 1995). 12 * Greenfield et al. (1970) recorded protracted <- 9 - spawning (March-July) for the Santa Anna sucker, Catostomussantaanae, in California; how- 86 6 was and ever, peak spawning during May June. c:P "~7------~ 3 Similarly, Deacon and Minckley (1975) docu- mented extended spawning (December to per- for C. clarki in Ar- haps July) Aravaipa Creek, 60 80 100 120 140 160 180 izona. TOTALLENGTH IN MLLIMETERS Breeding colors were more often present in FIG. of gonad index on total male than in female Rio Grande suckers. Greater 1--Regression length of suckersto delimitprobable size at maturity.Dashed coloration in male Rio Grande suckers may be lines are 95%confidence limits of meansfor both fitted important for females to locate, attract, and stim- (lower two) and predicted(upper) regressionlines. ulate males in the spawning act during more tur- bid conditions of spring runoff resulting from increased suspended sediment. Orange-red stripes because of hybridization with the white sucker, are present in both sexes of the desert sucker C. commersoni.There is a need for a comprehen- (Smith, 1966). Color was more common and pro- sive status survey of the Rio Grande sucker to nounced in the spring than in summer or in the enable managers to more effectively assess strat- autumn. egies for management and perhaps insure sus- Tuberculation was present in both male and tainability of natural populations in the wild. female suckers, but was more pronounced in the Such a survey is underway through a cooperative males, primarily on the head and gular region effort by New Mexico State University and Unit- (Table 2). Tuberculation has been described as ed States Forest Service research, Flagstaff, Ari- being most developed in male bluehead suckers, zona. C. discobolus(Miller and Hubbs, 1960), and only Additional reproductive information is needed in ripe male flannelmouth suckers (Cross, 1975). on the Rio Grande sucker in other streams within In summary, reproductive activity and traits of its range in New Mexico. Because color devel- the Rio Grande sucker in Rio de las Vacas par- opment was significantly related to time, more alleled the variability described in the literature intensive sampling (weekly or biweekly) during for congeners. To date, most of the information spawning peaks and further analyses of color, on the genus has been qualitative and descriptive fecundity, GI, and maturation of ova are needed and not as detailed as that reported by Andreasen to substantiate whether spawning is unimodal or and Barnes (1975) for the Great Basin region. bimodal in pattern. In addition, its interactions Such a lack of biological studies results, in part, with other members of both the native fish com- from the erroneous concept that suckers are "rough munity (e.g., longnose dace (Rhinichthys catarac- fish" and are "harmful" to other species, es- tae), Rio Grande Chub (Gila pandora) and the pecially trout (Holey et al., 1979). Indeed, suck- native Rio Grande cutthroat trout (Oncorhynchus ers more probably are a source of food for intro- clarki virginalis)) and the introduced portion of duced and native salmonid species. the community (e.g., brown (Salmo trutta), brook Even suckers (e.g., Cui-ui, Chasmistes cujas, (Salvelinus fontinalis), and rainbow (Oncorhyn- and Sonora C. insignis and desert C. clarki suck- chus mykiss) trouts) need documentation. ers) can become endangered and candidate species as a result of human activities. Biological infor- LITERATURECITED mation on these species is necessary to manage ANDREASEN,J. K., AND J. R. BARNES. 1975. Re- these species and prevent their extinction. Rio productivelife history of Catostomusardens and C. Grande suckers are reported to be almost extir- discobolusin the Weber River, Utah. Copeia, 1975: pated from Colorado, and are steadily disap- 643-648. pearing from streams in New Mexico, largely BAIRD,S. F., ANDC. GIRARD. 1854. Descriptions of June 1995 Notes 241

new species of fishes collected in Texas, New Mex- MINCKLEY,W. L. 1973. Fishes of Arizona. Arizona ico, and Sonora, by Mr. John H. Clark, on the Game and Fish Dept., Phoenix. United States and Mexico boundary survey, and in RAUSCH,R. R. 1963. Age and growth of the Rio Texas by Capt. Van Vliet, U.S.A., Second part. Grande mountain-sucker, Pantosteusplebeius (Baird Proc. Acad. Nat. Sci. Phila. 7:24-29. and Girard). Unpubl. M.S. thesis, Univ. of New CROSS,J. N. 1975. Ecological distribution of the Mexico, Albuquerque. fishes of the Virgin River (Utah, Arizona, Nevada). RINNE,J. N. 1988. Grazing effects on stream habitat West. Interst. Comm. Higher Ed., Boulder, Col- and fishes: research design considerations. N. Amer. orado. Jour. Fish. Mgmt., 8:240-247. DEACON,J. E., ANDW. L. MINCKLEY.1975. Desert 1995. Reproductive biology of the Rio Gran- fishes. Pp. 166-179, in Desert biology (G. W. de chub, Gila pandora (Teleosotomi: Cyprinifor- Brown, ed.). Vol 11:385-488, Academic Press, New mes) in a montane stream, New Mexico. South- York. western Nat., 40(1):107-110. GREENFIELD,D. W., S. T. Ross, ANDG. D. DECKERT. RINNE, W. E. 1971. The life history of Lepidomeda 1970. Some aspects of the life history of the Santa mollispinis mollispinis (the Virgin River spinedace) Ana sucker, Catostomus santaanae (Snyder). Cali- a unique western cyprinid. Unpubl. M.S. thesis, fornia Fish and Game, 56:166-179. Univ. of Nevada, Las Vegas. HENDRICKSON,D. A., W. L. MINCKLEY,R. R. MIL- SIGLER, W. F., AND R. R. MILLER. 1963. Fishes of LER,D. J. SIEBERT, AND P. H. MINCKLEY. 1980. Utah. Utah Dept. Fish and Game, Salt Lake City. Fishes of the Rio Yaqui Basin, Mexico and the SMITH, G. R. 1966. Distribution and evolution of United States. J. Ariz-Nev. Acad. Sci. 15(3):65- the North American catostomid fishes of the sub- 106. genus Pantosteus, genus Catostomus. Misc. Publ. HOLEY, M., B. HOLLENDER, M. IMHOF, R. JESIEN, Mus. of Zool., Univ. Michigan, 29:1-132. R. KONOPACKY,M. TONEYS, AND D. COBLE. 1979. SUBLETTE, J. E., M. D. HATCH, AND M. SUBLETTE. "Never give a sucker an even break." Fisheries, 1990. The fishes of New Mexico. Univ. of New 4:2-6. Mexico Press, Albuquerque. KOSTER,W. J. 1957. Guide to the fishes of New SZARO,R. C., AND J. N. RINNE. 1988. Ecosystem Mexico. Univ. New Mexico Press, Albuquerque. approach to management of southwestern riparian MILLER,R. R., ANDC. L. HUBBS. 1960. The spiny- communities. Trans. 53rd N. Amer. Wildl. and rayed cyprinid fishes (Plagopterini) of the Colorado Nat. Res. Conf., 53:502-511. River system in western North America. Misc. Publ. Mus. Zool., Univ. Michigan, 115:1-39.

MARKING OTOLITHS IN RAZORBACK SUCKER EMBRYOS AND LARVAE WITH FLUORESCENT CHEMICALS

ROBERT T. MUTH AND STEVEN M. MEISMER

Larval Fish Laboratory,Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, CO 80523

Efforts to recover the endangered razorback ing technique could also be used in field mark- sucker (Xyrauchen texanus) include hatchery recapture studies to facilitate investigation of the propagation of fish for reintroduction and re- early biology of razorback sucker and fate of re- search projects, documentation of reproduction introduced fish. and recruitment in the wild, and evaluation of Marking otoliths of fish has great potential for reasons for low recruitment and ways to improve use in stock identification, assessment of stocking survival of young fish. Minckley et al. (1991) success, and life-history studies (Brothers, 1990; recommended marking hatchery-produced razor- Buckley and Blankenship, 1990). One technique back sucker to distinguish them from fish pro- for rapid mass marking is incorporation of fluo- duced naturally. Because razorback sucker are rescent chemicals in otoliths by immersion of fish sometimes stocked in large numbers as larvae or embryos or larvae in solutions of these chemicals. small juveniles, a mass-marking technique ap- Two compounds proven effective for this tech- plicable to early life stages is required. The mark- nique are alizarin complexone (ALC) and tet-