In June 2009, the National Park Service translocated 300 juvenile humpback chub from the Little Colorado River to Shinumo Creek in Grand Canyon National Park. The goal of this experiment is to obtain information about how this endangered species will respond to translocation in another tributary.

This project will enable biologists to assess the feasibility of using translocation to establish an offsite refuge and potentially an additional aggregation of humpback chub in Grand Canyon. Regardless of the experiment’s success, it will increase the understanding of conservation efforts that must be undertaken in order to ensure that this native fish continues to survive in Grand Canyon. 

A Colorado River Native

The humpback chub (Gila cypha) is an unusual-looking member of the minnow family that is endemic, or native to the Colorado River basin. These fish, which can live as long as 30 years and reach lengths of almost 20 inches, are characterized by large fins and pronounced humps behind the heads of adults.

The humpback chub is one of eight species of fish native to the Colorado River in Grand Canyon National Park. Six of these species of fish are also endemic to the Colorado River basin. The Colorado River has the highest percentage of endemic fish of any river system in the United States because of the basin’s unique geology and hydrology. Like the other endemic fish, the humpback chub is specifically adapted to natural conditions of the Colorado River—high turbidity, and seasonally variable flows and temperatures. Humpback chub are found in deep, swift canyon reaches of the Colorado River and its large tributaries.

Relatively little is known about the populations of this fish in Grand Canyon prior to the closure of Glen Canyon Dam. Today, there are only six significant populations of humpback chub remaining in the Colorado River basin. The Grand Canyon contains the largest of these remnant populations.

An Endangered Species

The humpback chub was first listed as an endangered species in 1967 and today is protected under the Endangered Species Act. The decline in the humpback chub populations is due to a variety of significant human-caused changes to aquatic habitat in the Colorado River basin.

In Grand Canyon, humpback chub face a dam-altered ecosystem as well as competition with and predation by non-native fish such as rainbow and brown trout that thrive in the clear cold waters of the post-dam Colorado River. Nonnative parasites such as the Asian tapeworm and the possibility of a catastrophic event such as a hazardous materials spill into the Little Colorado River are also significant threats.  

In Grand Canyon, the largest humpback chub population is near the confluence of the Little Colorado River and the Colorado River. These fish spawn in the Little Colorado River because the water released from Glen Canyon Dam in the mainstem Colorado River is too cold for successful reproduction there. The conservation of this endangered species is a critical component of Colorado River management in Grand Canyon and the establishment of second reproducing humpback chub population below Glen Canyon Dam would be an important forward step.

One of the options for reaching this goal is the establishment of a satellite humpback chub population in a suitable Grand Canyon tributary. Historically, humpback chub would have used other tributaries besides the Little Colorado River but currently may be excluded from such tributaries due to competition and predation by nonnative fish species. Recently, biologists successfully translocated humpback chub within the Little Colorado River into previously unoccupied habitat above a set of barrier falls. This action set the precedent for a potentially successful translocation in another Grand Canyon tributary that may provide suitable habitat.

Shinumo Creek

Shinumo Creek is a small, clear tributary stream that joins the Colorado River at approximately River Mile 109. It is fed by springs in the Redwall Limestone and other aquifers and by surface flow from the North Rim, especially during spring snowmelt. Shinumo Creek averages about 13 ft (4 m) wide and has dense vegetation along the shoreline and a good abundance of aquatic and riparian invertebrates.

Biologists selected Shinumo Creek as the site for this translocation experiment because it was determined to be a suitable tributary in Grand Canyon for humpback chub based on habitat evaluation. Several characteristics of Shinumo Creek, including water quality, water temperature, and available foodbase, may provide acceptable habitat for humpback chub.

One of the most important features of Shinumo Creek that biologists evaluated is the presence of barrier falls just above its confluence with the Colorado River.

A 15 feet (5 m) waterfall located a few hundred yards (meters) above the Colorado River isolates acceptable humpback chub habitat from non-native predator fish in the mainstem Colorado River.

Upstream of the fish barrier, two species of native fish, speckled dace and bluehead suckers, and only one nonnative species, rainbow trout, live in the stream. Native fish are more abundant than rainbow trout, indicating that some co-existence may be possible between these competing species.

Translocation Plan

In July and October 2008, crews of biologists from the National Park Service, Arizona Game and Fish Department, U.S. Fish and Wildlife Service and Grand Canyon Wildlands Council used hoop-nets and seines to capture juvenile humpback chub near the mouth of the Little Colorado River.

These 2 – 4 inch (50 – 130 mm) fish were transported out of the canyon by helicopter. The small humpback chub were treated to remove parasites at the Arizona Game and Fish Department Bubbling Ponds Fish Hatchery for approximately one month.

The fish were then transferred to the U.S. fish and Wildlife Service Dexter National Fish Hatchery and Technology Center, in Dexter NM to overwinter and grow to a size that would allow identification tags to be implanted. PIT (passive integrated transponder) tags, small electronic tags that aid in monitoring after translocation, were implanted within the fish while they were at the hatchery a month before the translocation.

On June 15^th, the fish were transported again by helicopter to a landing site near Bass Camp at Shinumo Creek.

Prior to the release of the humpback chub into Shinumo Creek, a team of biologists used electrofishing techniques to survey the existing fish community. Non-native rainbow trout were also removed from the translocation reach. Biologists tempered the humpback chub to Shinumo Creek water conditions, and then released them into stream reaches with suitable habitat. 

The field work for this translocation project is strictly regulated in the permit issued by National Park Service, the Arizona Game and Fish Department and the U.S. Fish and Wildlife Service.

This project was determined to have no adverse impacts on the park’s natural and cultural resources. Additionally, helicopter landing zones, campsites for field personnel, and many aspects of field logistics were designed to minimize impacts to visitors in these backcountry areas.

There are no closures at Shinumo Creek because of this translocation experiment.

Research and Monitoring

An intensive three-year monitoring program will follow the translocation of humpback chub into Shinumo Creek. Biologists will evaluate the success of the humpback chub translocation using established fish surveying techniques such as snorkeling, hoop-netting, seining, and electrofishing.

Data will be collected on the size, condition and health of humpback chub and their distribution in the translocation reach.

The habitat characteristics of Shinumo Creek, including water flow, water quality and temperature, and other variables, will also be monitored. A PIT tag antenna placed near the falls will record any fish that are washed out of the stream by monsoonal floods.

Specific questions to be evaluated include whether the young humpback chub survive the translocation and if they will remain in Shinumo Creek.

If they survive in Shinumo Creek, will the humpback chub grow, mature and reproduce there? If so, will their offspring remain in Shinumo Creek? If the translocation is successful, genetics monitoring will be initiated to ensure that inbreeding or genetic drift does not occur in the Shinumo Creek population. Additional translocations to augment this population will be considered based upon the analysis of the first year’s findings.

The experiment of translocating young humpback chub into Shinumo Creek is an important opportunity to assess the effectiveness of translocation as a conservation strategy for this endangered species.

The information gained via this experiment will lead to a better understanding of the methods needed to establish a second humpback chub population in Grand Canyon. 

Related Information

Project Cooperators

U.S. Bureau of Reclamation

U.S. Fish & Wildlife Service

Arizona Game & Fish

Grand Canyon Wildlands Council

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Canyon Sketches Vol 12 - August 2009
300 Humpback Chub Translocated into Shinumo Creek
On June 15, 300 young humpback chub were translocated from the Little Colorado River to Shinumo Creek in order assess the feasibility of establishing an additional population of this endangered species in a Grand Canyon tributary.

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