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Contact: Maureen Oltrogge, 928-638-7779
Contact: Brian Healy, 928-638-7453
The humpback chub (Gila cypha), an endangered fish species endemic to the Colorado River basin, is well adapted to natural conditions of the Colorado River including high turbidity and seasonally variable flows and temperatures. Human-caused changes to the Colorado River ecosystem, including the introduction of non-native fish species as well as dam-induced changes in flow and temperature, have caused serious declines in wild populations. Today the largest remaining population in the world is found near the confluence of the Colorado River and Little Colorado River in Grand Canyon.
The translocation of juvenile humpback chub to Colorado River tributaries is part of a native fish conservation program in Grand Canyon National Park. Havasu Creek joins the Colorado River at River Mile 157 and is very similar to the Little Colorado River in water chemistry and physical habitat, and has fewer non-native fish predators than other Grand Canyon tributaries or the Colorado River.
Tributary translocations are a multi-faceted conservation tool for native fish. First, they may lead to the establishment of additional spawning populations of humpback chub in Grand Canyon, thereby increasing the species' odds of survival in the canyon. Tributaries may also provide rearing, or grow-out, habitat for young chub. Fish that are larger when they reach the colder Colorado River have a greater chance of survival due to their increased size, and thus may add to the Grand Canyon humpback chub population.
Tributary translocations in Grand Canyon National Park began in 2009 with the initial translocation of 302 young humpback chub to Shinumo Creek. The translocation program was expanded last year to include Havasu Creek when 243 fish were released. Three hundred additional young chub will be released into deep pools in Havasu Creek during the May 13th release.
The juvenile humpback chub that will be released in Havasu Creek were captured in 2011 from the Little Colorado River. The fish were treated to remove any parasites that may be present, kept overwinter, and then implanted with passive integrated transponder (PIT) tags to uniquely identify individual fish, at the U.S. Fish and Wildlife Service's Dexter National Fish Hatchery and Technology Center in New Mexico.
Grand Canyon National Park Fisheries Program Manager Brian Healy said, "The 2011 translocation went really well. A large percentage of the translocated chub were recaptured during monitoring efforts in October, and preliminary data indicate that the fish have an extremely high growth rate."
Healy added, "Prior to translocation in June, and again in October, we caught a few wild untagged humpback chub in Havasu Creek that arrived there without help from us. Their presence demonstrates that Havasu Creek may provide suitable humpback chub habitat, but we'll know more in the next couple of years as we monitor for reproduction, growth, and survival of the translocated fish."
Grand Canyon National Park Superintendent David Uberuaga said, "I'm excited about the second humpback chub translocation to Havasu Creek. It is an important part of the park's efforts to protect its native fish species and the monitoring results will inform our park-wide fish management planning efforts."
There are no closures at Havasu Creek related to translocation activities. Fisheries biologists from the National Park Service and the U.S. Fish and Wildlife Service will monitor the fish community in Havasu Creek prior to this year's translocation, and conduct additional monitoring in October.
In order to minimize interference with recreational boaters at the mouth of Havasu Creek, crews hike in and out of the Havasu Creek from Hualapai Hilltop and camp away from the river. Healy said, "As part of the planning for this project, we carefully evaluated potential impacts to visitors and to the wilderness characteristics of Havasu Creek. Helicopter support for the monitoring work and for the transport of the young humpback chub was determined to have the least impact to park resources and visitor experience, while also minimizing stress to the fish"
Anglers should be familiar with the identifying characteristics of humpback chub to avoid any accidental capture of these endangered fish. Young humpback chub are silver, have small eyes and large fins, but have not yet developed the pronounced hump behind their head. If any humpback chub are incidentally caught, they must be immediately released unharmed.
For more information, please contact Brian Healy, Fisheries Program Manager at 928-638-7453 or Maureen Oltrogge, Public Affairs Officer, at 928-638-7779. Additional information on tributary translocation of humpback chub translocation is available online at https://www.nps.gov/grca/naturescience/shinumotransloc.htm.