Thermal Requirements of the Bonytail (Gila elegans): Application to Propagation and Thermal-Regime Management of Rivers of the Colorado River Basin Author(s): Kevin M. Kappenman , Elijah S. Cureton , Jason Ilgen , Matt Toner , William C. Fraser , and Greg A. Kindschi Source: The Southwestern Naturalist, 57(4):421-429. 2012. Published By: Southwestern Association of Naturalists DOI: http://dx.doi.org/10.1894/0038-4909-57.4.421 URL: http://www.bioone.org/doi/full/10.1894/0038-4909-57.4.421 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. THE SOUTHWESTERN NATURALIST 57(4): 421–429 DECEMBER 2012 THERMAL REQUIREMENTS OF THE BONYTAIL (GILA ELEGANS): APPLICATION TO PROPAGATION AND THERMAL-REGIME MANAGEMENT OF RIVERS OF THE COLORADO RIVER BASIN * KEVIN M. KAPPENMAN, ELIJAH S. CURETON,JASON ILGEN,MATT TONER,WILLIAM C. FRASER, AND GREG A. KINDSCHI United States Fish and Wildlife Service, Bozeman Fish Technology Center, 4050 Bridger Canyon Road, Bozeman, MT 59715 (KMK, ESC, JI, MT, WCF) 505 North Valley Drive, Bozeman, MT 59718 (GAK) *Correspondent: [email protected] ABSTRACT—We performed experimental trials on hatchery-reared juvenile bonytails (Gila elegans) using the acclimated-chronic-exposure method. Bonytails were exposed to 8–308C for 112 days to determine effects on growth, condition factor, composition of body, and survival. Survival was ‡98% for all treatments. The predicted temperature was 25.98C for maximum gain in weight and 14.28C for zero gain. Temperatures <148C depressed growth, 14–208C provided incremental growth, and 22–268C allowed accelerated growth. We hypothesize that temperatures during propagation and seasonal temperatures of rivers that are 22–268C, or both, would maximize growth of juveniles and might promote higher survival because bonytails would be less vulnerable to predation, and have greater energy reserves and increased metabolic efficiency. RESUMEN—Subadultos de la carpa elegante (Gila elegans) criados en cautiverio fueron sometidos a pruebas experimentales utilizando el m´etodo de aclimataci´on y exposici´on cr´onica. Utilizamos exposiciones entre 8 y 308C con una duraci´on de 112 d´ıas para determinar los efectos en el crecimiento, condici´on, composici´on corporal, y sobrevivencia. La sobrevivencia fue ‡98% en todos los tratamientos. Las temperaturas predichas para obtener crecimiento de peso m´aximo y de cero fueron de 25.98C y 14.28C, respectivamente. Temperaturas <148C impidieron el crecimiento, las entre 14 y 208C incrementaron el crecimiento gradual, mientras que las entre 22–268C aceleraron el crecimiento. Proponemos la hip´otesis de que las temperaturas durante la propagaci´on y las temperaturas estacionales de los r´ıos entre 22–268C, o ambas, pueden maximizar el crecimiento de los juveniles y pueden promover m´as alta sobrevivencia porque las carpas elegantes ser´an menos vulnerables a ala depredaci´on, y tendr´an m´as reservas energ´eticas e incrementar´an su eficiencia metab´olica. The bonytail (Gila elegans) is endemic to the Colorado necessary to recover the species. The two principal River Basin and once inhabited the large, warm-water limiting factors that prohibit recruitment are altered rivers of the basin (United States Fish and Wildlife thermal regimes and predation by nonnative species Service, 1984, 2002a). Altered hydro-regimes and reduc- (Minckley, 1983, 1991; Marsh, 1985; Clarkson and Childs, tion in floodplains occurring in the era of dam building 2000; Bestgen, 2008). Changes to thermal habitats have in the early 1900s reduced habitat available to bonytails, occurred both from a direct impact of in-river hypolim- size of populations, and historical range (Minckley and netic releases from dams and a loss of natural inundation Deacon, 1968; Holden and Stalnaker, 1970; United States of floodplains that historically provided warmer backwa- Fish and Wildlife Service, 2002a). A viable wild popula- ter areas. Introduction of nonnative piscivorous species is, tion might no longer exist and potential for recruitment in general, a consequence of introductions of sport fish. appears to be limited to bonytails released from propa- Three other endangered species of fish inhabit the gation programs (Kaeding et al., 1986; Minckley et al., Colorado River Basin, the humpback chub Gila cypha, 2003; Bestgen et al., 2008). The bonytail was listed as Colorado pikeminnow Ptychocheilus lucius, and razorback endangered in 1980 (United States Fish and Wildlife sucker Xyrauchen texanus (United States Fish and Wildlife Service, 1984) and remains one of the most imperiled Service, 2002b, 2002c, 2002d). Among native fishes of the species of fish in the United States. Colorado Basin, these three large-bodied species along The Bonytail Recovery Plan (United States Fish and with the bonytail commonly are referred to as the big- Wildlife Service, 1984) identified factors believed to be river fishes of the Colorado River (Minckley et al., 2003). responsible for causing declines and outlined actions Life histories of bonytails and these three sympatric 422 The Southwestern Naturalist vol. 57, no. 4 species are similar. Often, the conclusion of a study (or a Kappenman et al., 2009). The objective of our study was result from a management action) pertaining to one of to determine thermal requirements of juvenile bonytails. these species can be applied to another member of the We examined effects of temperature of water on survival, group. For example, the temperature regime that growth, condition factor, and constituents in the body promotes the life cycle of one species might likely be (e.g., proteins, lipids, moisture, and ash) of juveniles beneficial to the sympatric group, or the size needed by across a range of temperatures they might be exposed to subadults of one species to avoid early mortality in life in rivers and in propagation programs at hatcheries. from nonnative predation might be similar among species Determining optimal thermal regime for bonytails might (Minckley et al., 1991; Schooley and Marsh, 2007). provide managers of hatcheries the ability to promote Although research specific to bonytails is limited, increased growth and produce healthier fish more likely researchers have produced a body of literature for the to survive in the river, and also provide guidance on four big-river fishes that demonstrates that alterations of thermal habitats to managers of rivers. temperature have reduced survival of embryos, reduced rates of growth of larvae and juveniles, and slow growth MATERIALS AND METHODS—Our study was conducted at the has increased early-life mortality (Minckley, 1983, 1991; United States Fish and Wildlife Service Bozeman Fish Technol- Marsh, 1985; Kaeding and Osmundson, 1988; Clarkson ogy Center in Bozeman, Gallatin County, Montana. Adult and Childs, 2000; Tyus and Saunders, 2000; Minckley et broodstock were spawned at the United States Fish and Wildlife Service Dexter National Fish Hatchery and Technology Center, al., 2003; Schooley and Marsh, 2007). Researchers have Chaves County, New Mexico. The Bozeman Fish Technology further identified that, although temperature has played Center received embryos on 25 March 2008. Embryos were a significant role in reduction of bonytails and the three incubated and hatched at 188C and survival to hatch was >90%. other species, temperature alone is not the single limiting During April–September 2008, bonytails were held in the factor (Marsh, 1985; Kaeding et al., 1986; United States quarantine facility at Bozeman Fish Technology Center. During Fish and Wildlife Service, 2002a, 2002b, 2002c, 2002d). the larval-to-juvenile transition, bonytails were maintained at Predation by nonnatives is a causative agent in the 188C in circular tanks and fed to excess with a diet of Otohime continued demise of these four species (Minckley et al., Marine (BioKyowa; Kyowa Hakko Kogyo Co., Ltd., Cape 2003; Clarkson et al., 2005; Schooley and Marsh, 2007). Girardeau, Missouri), live Artemia reared at Bozeman Fish The combination of an altered riverscape and interaction Technology Center from cultured cysts (Argent Laboratories, of native and nonnative species with competing and Redmond, Washington), and lyophilized freeze-dried Cyclop- eeze (Argent Laboratories, Redmond, Washington). Survival of nonadapted life histories has led to what appears to be larvae was high (mortality <5–15%) from hatching to transition the largest-scaled expansion and displacement of species to exogenous feed. Larvae gradually were transitioned onto a of fish in a North American river basin (Olden et al., diet of Otohime Marine, size of feed was increased as fish grew, 2006). and feed-to-excess rations were