In a remarkable comeback, Razorback suckers are once again spawning in the lower Colorado River within Grand Canyon National Park, an event not seen in more than two decades, according to fisheries experts.
Interior Department officials say larval Razorback suckers, believed to have been missing from the Grand Canyon since the 1990s, recently were spotted within the park's waters. That, they say, provides evidence that this endangered species may be naturally reproducing in an area where the species has not been seen in over 20 years.
"The discovery that the Razorback suckers are spawning in the national park far upstream from Lake Mead is good news for this endangered species,' said Assistant Secretary for Water and Science Anne Castle. 'It is also a demonstration of the power of the partnership among Interior's Bureau of Reclamation, National Park Service, U.S. Fish and Wildlife Service and U.S. Geological Survey, who have worked for recovery of this species side-by-side with Arizona state officials, Indian tribes, private landowners and researchers.'
The larval fish were first detected on April 14, and again in multiple samples from April and May, confirming the occurrence of spawning and indicating that suitable habitat is available to support larger populations of this species.
'I'm proud to see that Grand Canyon provides habitat once again for this unique species, as well as for the endangered Humpback chub, and I'm committed to working with our cooperators to continue native fish conservation efforts within the park,' said Grand Canyon Superintendent Dave Uberuaga.
Unique to the Colorado River Basin, Razorback suckers were once widespread and abundant throughout the Colorado River and its tributaries from the Green River in Wyoming to the Gulf of California. Because of basin-wide alterations in habitat and the introduction of non-native species, however, spawning and survival to adulthood were known to occur only in Lake Mead National Recreation Area, according to an Interior Department release.
Researchers typically determine the age of captured Razorback suckers and monitor their habitat use, reproduction and movements, using specialized equipment designed to detect signals emitted from sonic tags implanted within the fish.
Although the monitoring of the Razorback sucker has been conducted in the Lake Mead National Recreation Area for several years, the study was extended, beginning in the spring of 2014, from the Lake Mead Inflow area near Pearce Ferry upstream to Lava Falls Rapid within Grand Canyon National Park.
On March 16, in cooperation with the Nevada Department of Wildlife, BIO-WEST, Inc. and the Arizona Game and Fish Department, the National Park Service and U.S. Bureau of Reclamation successfully released nine adult endangered razorback suckers in the Colorado River within Grand Canyon National Park, downstream of Lava Falls (River Mile 180).
During a subsequent April monitoring trip in Grand Canyon, conducted by BIO-WEST, Inc., American Southwest Ichthyological Researchers LLC, Bureau of Reclamation and the National Park Service, biologists located several newly released sonic-tagged fish, as well as previously tagged fish that migrated upstream from Lake Mead.
'The most surprising result was finding larval Razorback suckers at nine of the 47 locations in the park ' far upstream from Lake Mead,' said Mark McKinstry, a biologist with the Bureau of Reclamation.
These results illustrate the resiliency of this fish to adapt to changing conditions according to Brandon Albrecht and Ron Kegerries of BIO-WEST, Inc., who have been monitoring the Lake Mead population for 18 years and are lead biologists for the Grand Canyon Razorback research.
Brian Healy, fisheries program manager for the national park, said 'Razorback suckers continue to surprise us in Grand Canyon, first with the discovery of adults after 20 years of absence, and now with spawning within the park. We're all hoping to see evidence that these larval fish survive to adulthood in the coming years.'
'This exciting news suggests that Grand Canyon is becoming a significant basin-wide haven for the endangered fishes in the Colorado River,' said Lesley Fitzpatrick, biologist for the U.S. Fish and Wildlife Service.
Razorback suckers are named for the bony keel on their backs. They are the largest species of suckers that live in the Colorado River and reach a maximum length of 36 inches. They can live 40 years or more, feeding on a variety of insects and crustaceans.