(CN) – When the U.S. Fish and Wildlife Service takes a species off the endangered list, the move is typically greeted with effusive praise from wildlife conservation groups and offered as proof that conservation in concert with recovery programs works.
But the delisting of the Kanab ambersnail, which makes its home in the Grand Canyon, is different.
The snail was delisted not because its numbers have rebounded dramatically, but because scientists have concluded the creature in question is likely not that genetically different from other ambersnails distributed throughout the high deserts of southern Utah and northern Arizona.
“Available genetic evidence suggests that at least one population identified as Kanab ambersnail is more closely related to other nearby Oxyloma populations than it is to the other two Kanab ambersnail populations,” the service said in the final act document released Friday.
In other words, at least one of the Kanab ambersnail populations, which was historically found in three distinct springs in Utah and Arizona, is more related to another ambersnail population found outside the region in question than they are to each other. Oxyloma is the scientific name for ambersnails, which are characterized by translucent shells that appear amber when empty.
They were first discovered by biologist James Ferriss in 1909. Biologists at the time believed the ambersnails in question were genetically distinct but acknowledged more research was required to establish their taxonomic independence.
When the Kanab ambersnails were first listed under the endangered species act in 1992, they were thought to only exist in three separate spots – Kanab Creek Canyon and Three Lakes in Utah as well as Vasey’s Paradise in Arizona.
Vasey’s Paradise is a small spring or seep located about 33 miles downstream from Lee’s Ferry on the Colorado River. Located squarely within Grand Canyon National Park, it has been protected from development and copious groves of poison ivy deter potential visitors.
But the snail has struggled due to frequent flooding, sometimes caused by water managers releasing large amounts of water from the Glen Canyon Dam situated just upstream.
In Utah, livestock managers entirely depleted a small spring at the Kanab Creek Canyon location outside of the small town, causing the local extinction of the snail there. The species at Three Lakes near Kanab has fared better.
Kanab is a small town on the eastern flank of Zion National Park and on the doorstep of the Grand Staircase-Escalante National Monument, serving as a headquarters for tourists to explore the spectacular scenery of Utah’s unique high desert.
While the species recovered somewhat in both places and was introduced to Upper Elves Canyon, also located in the Grand Canyon National Park about 83 miles downstream from Vasey’s Paradise, their recovery isn’t the reason for delisting as much as additional scientific studies have raised doubt as to whether the Kanab ambersnail is actually distinct from other ambersnail populations that flourish throughout the region.
Specifically, a research team studied the morphology and mitochondrial DNA patterns of the three distinct populations in questions and compared it with those of eight other populations found in Utah and Arizona.
“The authors concluded that the three populations of Kanab ambersnail are not a valid subspecies of Oxyloma haydeni and should instead be considered part of the same taxa as ambersnails from the eight other populations of Oxyloma in Utah and Arizona that were sampled for comparison,” the service wrote.
The delisting of species on taxonomic reasons is rare but not unheard of. The International Union for Conservation of Nature recognizes such delistings as “non-genuine” reasons rather than “genuine reasons” involving the reduction of threats and the introduction of conservation measures such as habitat restoration.