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Home , Bonytail chub, Colorado pikeminnow, Humpback chub, Ptychocheilus, Razorback sucker, Roundtail chub

Native of the Grand

Allison Dedrick

Abstract: Native fish in the evolved in a habitat that was extremely physically variable but biologically isolated from other river systems. The assemblage of fish species native to the Grand Canyon is highly endemic to the River basin: most of the species are found in no other river systems. With the construction of dams and other water infrastructure projects and the introduction of numerous nonnative fish species, the environment these fish now inhabit has switched to being more physically constant and biologically crowded. These changes have caused three of the eight fish species native to the Grand Canyon to be extirpated from the canyon stretch and left only one of the native species at population levels high enough to be considered common in Grand Canyon National Park. Four of the eight are listed as endangered and are now monitored and managed in attempts to recover their populations.

Freshwater habitat in the Grand Canyon: The basin (Figure 1) reaches into seven states and drains an area of at least 600,000 km2 (Graf 1985), with headwaters starting up in Colorado and finally ending in the southeast corner of at its border with . Prior to human involvement and water management, the stretch of the Colorado River that passes through the Grand Canyon was highly variable, with flows changing over a range of five orders of magnitude. Before the dams were put in place, a 40-year flow record from Yuma, Arizona showed flows ranging from 0.5 to almost 7,000 m3/s (Minckley 1991). Most of the water comes from snowmelt, causing higher flows in the spring and lower flows during the summer through the onset of winter, though summer storms can raise flows in tributaries temporarily. These widely varying but sometimes extremely high flows created a range of habitats, including deep pools, calm backwaters left by receding high waters, turbulent flow, and eddies. The geology of the rock underlying the Grand Canyon and larger Colorado River basin caused the water to be quite muddy and it was also often warm, particularly in the summer (Miller 1961).

Introduction to the fish: The larger Colorado River basin, which includes both the mainstem Colorado River and its tributaries, has fourteen species of native fish. Eight of the fourteen species native to the larger basin were native to the section of the river passing through the Grand Canyon: the speckled dace (Rhinichthys osculus), (Xyrauchen texanus), flannelmouth sucker (Catostomus latipinnis), bluehead sucker (Catostomus discobolus), ( lucius), ( robusta), (Gila cyhpa), and (Gila elegans) (Figure 2). These eight fish were once common to both the upper and lower basins of the Colorado River (Carlson and Mace 1989). Five of these species are still present in the canyon today – the humpback chub, razorback sucker, bluehead sucker, flannelmouth sucker, and speckled dace – but the other three have been extirpated from the Grand Canyon.

Figure 1: Map of the Colorado River Basin. The Grand Canyon begins just below the at Lee’s Ferry. The San Juan River and the Green River in the upper basin hold many of the remaining populations of native fish. Map source: Colorado River Commission of (http://crc.nv.gov/index.asp?m=maps).

The fish in the Colorado River basin show high endemism: six of the eight species native to the Grand Canyon are endemic to the Colorado River basin (Minckley 1991). Only two families of fish are represented in the fish species in the Grand Canyon: () and suckers (). The pattern of high endemism is not unique to fish but is found for other freshwater organisms in the Colorado River as well. The Colorado River has the lowest diversity of fish and highest endemism of river systems in the North America, likely due to the system’s isolation and the high variability of temperature and flow conditions in the mainstem and tributaries. The fish assemblage in the Grand Canyon is thought to have existed for about 6 million years, with the genera present since the Pliocene and speciation happening during the Pleistocene and early Holocene (Carlson and Muth 1989). The river system has likely been separated from other river systems for at least as long. **" *"

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Figure 2: Native fish of the Grand Canyon. Clockwise from upper right corner: speckled dace (Rhinichthys osculus), razorback sucker (Xyrauchen texanus), flannelmouth sucker (Catostomus latipinnis), bluehead sucker (Catostomus discobolus), Colorado pikeminnow (Ptychocheilus lucius), roundtail chub (Gila robusta), humpback chub (Gila cyhpa), and bonytail chub (Gila elegans). Species with a red box have been extirpated from the Grand Canyon, while species with a blue box are still present in the Grand Canyon. Species listed as federally endangered are designated with two red asterisks while the two species that are not endemic to the Grand Canyon are indicated with one black asterisk. Illustrations are by Joe Tomelleri (Grand Canyon National Park: http://www.nps.gov/grca/learn/nature/fish-native.htm).

Perhaps unsurprising due to their isolation and somewhat extreme environment, fish native to the Grand Canyon share some common characteristics. First, they tend to have a long life span: the Colorado pikeminnow is able to live up to 80 years and the chubs and suckers can live for 20-30 years (Minckley 1991). Since the conditions in the Grand Canyon were once so variable, both within and among years, having a long life span might have been a strategy to ensure that reproduction could be spread out over many years in the hopes that at least some of the years would have conditions favorable for reproduction and recruitment. Additionally, the native fish of the Grand Canyon are also relatively large-bodied. The Colorado pikeminnow can reach lengths of six feet and the chub and sucker species can reach almost two feet in length (Grand Canyon’s Extirpated Fish Species: National Park Service). The speckled dace, however, is neither particularly large nor long-lived, reaching only about four inches in length and living for two or three years. In addition to size and life span, fish of the Grand Canyon also share some physical characteristics. The species tend to have a streamlined shape, with small heads and eyes, large fins, and thick skin. These features might be advantageous for life in fast, turbulent water often laden with sediment (Minckley 1991). Several of the species also have humps behind their heads, most notably the humpback chub and the razorback sucker. The hump was once thought to be another characteristic to aid swimming in fast turbulent water but instead was found to increase drag and the energy required to maintain position in flow (Portz and Tyus 2004). Portz and Tyus argue that the humps are actually an example of convergent evolution in response to the predatory Colorado pikeminnow. By growing a hump, young fish could more quickly grow past the size vulnerable to predation by the Colorado pikeminnow.

Current status of Grand Canyon native fish: Four of the eight species native to the Grand Canyon have been listed as federally endangered: the humpback chub, bonytail chub, razorback sucker, and Colorado pikeminnow. Only the humpback chub and the razorback sucker are still present in the Grand Canyon, though both are rare. Of the five native fish species that remain in the Grand Canyon, only the speckled dace is common in the park and it lives primarily in the tributaries.

Bonytail chub: In addition to being absent from the Grand Canyon, the bonytail chub no longer has any reproductive populations in the wild. It was listed as endangered in 1980 and was essentially extirpated from the wild before biologists had much of a chance to study it so relatively little is known about its natural behaviors and habitat. By the late 1970s and early 1980s, biologists realized that they were seeing only adults and no young in the Grand Canyon so removed adults to be placed into hatcheries (Upper Colorado River Endangered Fish Recovery Program).

Humpback chub: The humpback chub was listed as endangered in 1967. There are six populations that remain in the overall Colorado River basin. Within the Grand Canyon, they are currently found almost exclusively at the confluence with the Little Colorado tributary, which is the largest population. The fish in the warmer waters of the tributary, as the mainstem waters are too cold. They face predation pressure from the trout populations upstream in the tailwater of the Glen Canyon Dam (Historical Native of Glen and Grand ) and also have trouble with nonnative parasites (Humpback Chub Tributary Tranlocations: National Park Service).

Razorback sucker: The razorback sucker was thought to be absent from the Grand Canyon for many decades but recently has been sighted spawning in the Grand Canyon again. Listed as federally endangered in 1991, a population in was thought to be the only remaining wild population. In 2012, however, larval razorback suckers were found at several sites in the Grand Canyon, creating hope that a population might be able to reestablish there (Oskin 2014).

Colorado pikeminnow: Listed in 1967 and given full protection with the passage of the Act in 1973, the Colorado pikeminnow has been extirpated from the Grand Canyon for several decades. The last known sighting in the Grand Canyon was in 1972 (Grand Canyon’s Extirpated Fish Species: National Park Service), though populations are still present in the upper part of the Colorado River basin above , particularly in the San Juan and Green Rivers. The Colorado pikeminnow was once the top predator in the Grand Canyon and historically undertook large spawning migrations with high spawning site fidelity. Though the fish can no longer migrate as freely or as far as they once did and are now restricted to about 25% of their former range, they do still migrate to spawn within the sub-basins in the Upper Colorado River Basin (Bestgen et al. 2005). These fish were once called “white ” due to their migratory spawning behavior (Minckley 1991).

Roundtail chub: The roundtail chub is very closely related to the humpback chub currently listed as a candidate species for listing. It has been extirpated from the Grand Canyon but is still present in other parts of the Colorado River system, and is actually the most populous of the three chub species overall in the Colorado River basin (Grand Canyon’s Extirpated Fish Species: National Park Service).

Causes of population declines: Changes to river habitat and the introduction of non-native fish species are the two primary causes of population declines in the native Grand Canyon fish over the past several decades. With the development of water projects and the introduction of fish from other systems, the Colorado River is no longer the variable isolated river system than enabled the native fish species to evolve and thrive. Changes in the water management and resulting river habitat have been substantial over the last century. There are now over 140 dams on the mainstem Colorado River and tributaries, in addition to water diversions that bring water across the basin, built to supply water and power to people in the southwest (Bestgen et al. 2005). Starting with the in 1935, the Colorado River has since become one of the most intensely managed in the United States (Carlson and Muth 1989). Water development and management has changed the water conditions. No longer warm, silty, and turbulent, the mainstem Colorado in the Grand Canyon is now much clearer and colder. Though flows oscillate on a daily basis in response to fluctuating power demands, there is no longer the same seasonal or inter-annual variability. Recently managers have been experimenting with releasing high flows for several days in attempts to mimic some of the natural hydrology, though the flows are nowhere near as high as natural peaks in flow were on the undammed river (Poff et al. 1997). These changes to the river have had negative effects on the native fish populations, particularly for reproduction and recruitment. The cold water can create water temperatures that are too low for larval development (Bestgen 2008). The lack of floods and extremely high flow events has reduced nursery and rearing habit, which often takes place in backwaters and slow- flowing flooded areas (Endangered Fish: U.S. Fish & Wildlife Service). For the Colorado pikeminnow, the dams might have had the additional effect of disrupting spawning migrations. Colorado pikeminnow might also have suffered overharvest, as they were once popular fish for eating starting with the Native Americans and early settlers (Grand Canyon’s Extirpated Fish Species: National Park Service). In addition to living in an altered habitat, the fish species are also no longer alone. At least 60 nonnative species have been introduced to the Colorado River, brought in as bait or stocked for fisheries or as forage for fisheries (Minckley 1991). These introduced fish include large predatory fish, such as the striped bass (Morone saxatilis), the northern pike ( lucius), and the rainbow trout (Oncorhynchus mykiss). These nonnative fish compete with the native fish for food and habitat and predate on them – particularly larvae and juveniles (Carpenter and Mueller 2008). Razorback suckers appear to be hybridizing with some of the introduced sucker species, also contributing to their decline (Endangered Fish: U.S. Fish & Wildlife Service). Both the physical habitat changes and the introduction of nonnative fish species have contributed to native fish decline but it seems likely that the nonnative fish might be having a more negative effect. In his assessment of the present and future status of native Grand Canyon fish, Minckley (1991) argues that since these fish evolved in a highly variable environment and are largely generalists rather than specialists, able to tolerate a wide range of conditions, changes to water management and dams alone wouldn’t have been able to cause such drastic population declines. These fish have been present in the Colorado River basin for millions of years, during which time the climate has been both wet and very dry. Even though the river conditions have changed due to water diversions and dams, they are likely still within the range of conditions that these fish can tolerate. Predation and competition by nonnative fish, however, is a new challenge that these fish have not evolved to handle so might be the stronger of the two negative pressures on the native Grand Canyon fish.

Management and recovery actions: Many agencies are involved with the management and recovery of the four endangered native fish, including federal and state agencies, with different agencies undertaking management actions in different parts of the Colorado River basin. There are several collaborative management groups in place or under development, including the Comprehensive Fisheries Management Plan, which will apply to the Grand Canyon National Park and the Glen Canyon National Recreation Area. The plan is being developed by the National Park Service along with the Arizona Game and Fish Department and U.S. Fish and Wildlife Service. Another group is the Upper Colorado River Endangered Fish Recovery Program, created in 1988 with the goal of providing compliance with the Endangered Species Act (ESA) for various water development and management activities, including Bureau of Reclamation dams and projects (2012-2013 Highlights). The program is currently involved in recovery projects for humpback chub, bonytail, Colorado pikeminnow, razorback sucker in the mainstem Colorado River and tributaries in Colorado, , and and provides ESA compliance for over 2000 water projects. For each species, there is a set of requirements and recovery targets that need to be achieved before the species can be downlisted or delisted. Typically, the goals for recovery include establishing multiple populations with hundreds or thousands of adults each and often require at least one population in both the upper and the lower Colorado River basin (ex. Bestgen et al. 2005).

Monitoring: Several agencies, both state and federal, are actively involved in monitoring and managing the native Grand Canyon fish, attempting to recover their populations. There is a considerable amount of monitoring that occurs, both in the Grand Canyon and in other parts of the Colorado River basin, particularly on the San Juan River and the Green River in the upper basin. Monitoring includes both larval and adult phases and increasingly makes use of tags to understand fish movement and habitat use, particularly for the Colorado pikeminnow and the razorback suckers (Kitcheyan and Montagne 2005). To help create long-term data sets and compare data collected by different agencies, there is an Interagency Standardized Monitoring Program (ISMP).

Stocking and translocation: For the four federally endangered species – the humpback chub, bonytail chub, Colorado pikeminnow, and razorback sucker – the management plans include hatchery production of fish for restocking. The Utah Department of Natural Resources operates a hatchery for all four species, with the goal of restocking fish in areas where suitable habitat still remains. The U.S. Fish and Wildlife Service also operates a hatchery that produces the four endangered fish for a combination of restocking and research. About 16,000 bonytail chub are stocked annually into the Green and Colorado Rivers but currently these fish have a very low survival rate. Researchers are doing tagging studies to better understand the behavior and fate of these released fish, since so little is known about bonytail chub in the wild. At least 15,000 razorback suckers are released into the Green River annually, all tagged so that they can be identified if recaptured later (Ouray National Fish Hatchery). Razorback suckers are also stocked into the Green and San Juan Rivers in the Upper Colorado River Basin. Colorado pikeminnow are stocked into the San Juan River and razorback suckers are stocked into the Green, San Juan, and Colorado Rivers. For humpback chub, the National Park Service began a program in 2009 to translocate some individuals from the population in the Little Colorado River tributary to other tributaries of the Grand Canyon (Humbpack Chub Tributary Translocations: National Park Service).

Nonnative fish removal: Nonnative fish, particularly trout, are removed in habitat areas that are particularly important to native fish. This includes mechanical removal of trout near Bright Angel Creek and the mouth of the Little Colorado River. Volunteers are also solicited to fish for nonnative fish and remove them (Comprehensive Fisheries Management Plan).

Habitat improvement: Though the habitat has been changed dramatically from what these fish evolved to survive in and is unlikely to return to that state soon, some agencies and groups do undertake habitat improvement projects. The Upper Colorado River Endangered Fish Recovery Program constructs fish passages on dams in the upper basin, re-opening up access to habitat that had been cut off. The group also installs fish screens on diversions so that fish are not accidentally led out of the river habitat. Though it has many things to consider in deciding flows and releases, the Bureau of Reclamation, which controls the operations of the dams, takes fish needs into consideration when possible in deciding how to release water.

Thoughts about the future Most of the native fish species of the Grand Canyon are hanging on precariously and have an uncertain future. They face two primary challenges: the modification of their habitat due to water infrastructure and interactions with nonnative species. It is unlikely that either of these problems will be resolved soon: we are not likely to tear down the dams or stop diverting water from the Colorado River, particularly as human populations in the southwestern United States continue to grow, and many of the nonnative fish species are so well established and numerous that it is not realistic to think will eradicate them. Three species are largely supported by hatcheries, which while they can boost numbers and keep a species from going extinct, can introduce non-natural selective pressures that can hinder recovery in the long run. Though all four endangered Grand Canyon fish species have stated recovery goals, none of them seem close to downlisting or delisting and absent large-scale changes in habitat and the nonnative fish assemblage, they seem unlikely to recover soon. It seems likely that in the wild these fish will be relegated to the least disturbed parts of the Colorado River basin, in the tributaries and upper parts of the basin. Concentrating efforts to support wild populations there while maintaining stock in captivity seems our best hope for keeping these fish around into the future.

References:

2012-2013 Highlights (Upper Colorado River Endangered Fish Recovery Program and San Juan River Basin Recovery Implementation Program).

Bestgen, K.R. (2008). Effects of Water Temperature on Growth of Razorback Sucker Larvae. Western North American Naturalist 68, 15–20.

Bestgen, K.R., Hawkins, J.A., White, G.C., Chrisopherson, K., Hudson, M., Fuller, M.H., Kitcheyan, D.C., Brunson, R., Badame, P., Haines, G.B., et al. (2005). Population Status of Colorado Pikeminnow in the Green River Basin, Utah and Colorado (Department of Fishery and Wildlife Biology, Colorado State University and U.S. Fish and Wildlife Service).

Carlson, C.A., and Muth, R.T. (1989). The Colorado River: lifeline of the American Southwest. Canadian Journal of Fisheries and Aquatic Sciences 106, 220–239.

Carpenter, J., and Mueller, G.A. (2008). Small Nonnative Fishes as Predators of Larval Razorback Suckers. The Southwestern Naturalist 53, 236–242.

Colorado River Basin. Colorado River Commission of Nevada. 07 March 2007. 11 March 2015. .

“Comprehensive Fisheries Management Plan.” National Park Service. Accessed 27 Feb. 2015. http://parkplanning.nps.gov/projectHome.cfm?parkID=65&projectID=35150.

“Endangered Fish.” National Park Service: Glen Canyon National Recreation Area. 27 Feb. 2015. .

“Endangered Fish.” U.S. Fish & Wildlife Service: Grand Junction Colorado River Fishery Project. 19 April 2013. 27 Feb. 2015. < http://www.fws.gov/grandjunctionfishandwildlife/endangeredfish.html>

Graf, W.L. (1985). The Colorado River: Instability and Basin Management. Association of American Geographers, Research Publications in Geography 1–86.

“Grand Canyon’s Extirpated Fish Species.” National Park Service: Grand Canyon National Park, Arizona. 27 Feb. 2015. < http://www.nps.gov/grca/learn/nature/fish-extirpated- species.htm>.

“Historical Native Fishes of Glen and Grand Canyons.” Glen Canyon Dam Adaptive Management Program. 4 April 2013. 27 Feb. 2015. .

“Humpback Chub Tributary Translocations.” National Park Service: Grand Canyon National Park, Arizona. Accessed 27 Feb. 2015. < http://www.nps.gov/grca/learn/nature/shinumotransloc.htm>.

Kitcheyan, C., and Montagne, M. (2005). Movement, migration, and habitat use by Colorado pikeminnow, Ptychocheilus lucius, in a regulated river below , Utah (Dinosaur National Monument: U.S. Fish and Wildlife Service).

Miller, R.R. (1961). Man and the Changing Fish Fauna of the American Southwest. Papers of the Michigan Academy of Science, Arts, and Letters 46, 365–404.

Minckley, W.L. (1991). Native Fishes of the Grand Canyon Region: An Obituary? In Colorado River Ecology and Dam Management: Proceedings of a Symposium May 24-25, 1990 Santa Fe , (Washington D.C.: National Academies Press), pp. 124–177.

Oskin, B. (2014). They’re Back! Endangered Fish Spawns in Grand Canyon. Live Science. Accessed March 3, 2014. .

“Ouray National Fish Hatchery.” U.S. Fish and Wildlife Service. 15 March 2011. 27 Feb. 2015. < http://www.fws.gov/ourayhatchery/>.

Poff, N.L., Allan, J.D., Bain, M.B., Karr, J.R., Prestegaard, K.L., Richter, B.D., Sparks, R.E., and Stromberg, J.C. (1997). The Natural Flow Regime. BioScience 47, 769–784.

Portz, D.E., and Tyus, H.M. (2004). Fish humps in two Colorado River fishes: a morphological response to cyprinid predation? Environmental Biology of Fishes 71, 233–245.

Upper Colorado River Endangered Fish Recovery Program. Accessed 27 Feb. 2015. < http://www.coloradoriverrecovery.org/>