The National Park Service and the U.S. Fish and Wildlife Service’s Bureau of Reclamation are working together to save an endangered freshwater fish, the humpback chub. The latest effort was the June 23, 2010, translocation of 300 young fish from the Colorado River to Shinumo Creek, near the Kaibab Plateau on Grand Canyon National Park’s North Rim.
The first group of humpback chub (Gila cypha) to be successfully relocated to Shinumo Creek arrived in 2009 as part of a multi-year experiment. The hope is that this Grand Canyon tributary of the Colorado River can become the home to a new spawning aggregation–an area where many fish come together to reproduce. Currently, the humpback chub only spawn and reach adulthood in a tributary of the Little Colorado River.
If this experiment works, it will provide researchers with significant data on the effectiveness of translocation as a way to protect this endangered species. Fish and Wildlife Service researchers will monitor the humpback chub population before planning any additional releases.
Although the humpback chub is well suited to the high velocity, seasonal variability, and high turbidity (or murkiness) of the Colorado River basin, human-caused changes to the river’s flow and ecosystem have devastated the population. The largest remaining habitat for the fish is near the confluence of the Colorado and Little Colorado Rivers in Grand Canyon.
Studies of the water quality, water temperature, and available food in Shinumo Creek suggest that it could be an ideal place to establish a new spawning ground. The barrier falls just above where Shinumo joins the Colorado River keeps invasive, predatory fish from accessing the creek, which is located approximately at River Mile 109.
The translocated fish were captured in their native habitat near the mouth of the Little Colorado River in 2009. They were treated to kill any parasites they might bring with them to Shinumo, kept over the winter, and then implanted with passive-integrated transponders, or PIT tags. PIT tags are glass-enclosed tracking devices that are surgically implanted under an animal’s skin to let wildlife researchers remotely monitor an their movement and health. Specialists at the U.S. Fish and Wildlife Service’s Dexter National Fish Hatchery and Technology Center in southeastern New Mexico will track the humpback chub populations. It was researchers at the Center who were able to confirm that fish from the first translocation were feeding and behaving normally almost immediately after being released.
Monitoring trips planned for June and again in September, combined with data from the PIT tag antenna, will allow biologists to assess the health and growth of the 2009 group of humpback chub. One element that will be closely studied is whether humpback chub will be able to withstand monsoonal flooding as a result of heavy rains or snowmelt. Shinumo Creek didn’t flood last year after the first translocation, so researchers are seeking more data.
While this program is still experimental, if it proves successful, the NPS may plan more translocation efforts as a way to restore native fish populations in the park. Juvenile humpback chub may have a greater chance of survival in the slightly calmer, warmer waters of Shinumo; larger fish may do better if they move to the Colorado River, which could lead to increased populations there. Grand Canyon National Park superintendent Steve Martin is looking forward to the results of the experiment. “I’m excited about the upcoming humpback chub translocation,” he says. “This conservation tool may become an important part of the recovery efforts for this Colorado River native fish.”
The National Park Service has no closures planned because of the translocation experiment, but they ask anglers in Shinumo Creek to immediately release any humpback chub they may accidentally catch. The fish can be identified by their silver color, small eyes, and large fins. Juvenile fish will not yet have the pronounced hump behind their head that gives the species its name.