The least chub, as its name implies, is not a particularly large fish, but Tooele Army Depot officials are committed to work with the state to preserve it.
Biologists from the Utah Division of Wildlife Resources spent Monday counting and measuring — in millimeters — the more than 2,000 least chub they trapped from two refuge ponds at Tooele Army Depot South Area in Rush Valley.
Though the species is not native to the area, the rapid growth of the refuge population bodes well for the least chub’s odds of survival, said Biologist Mark Grover who specializes in native aquatics.
About 500 least chub were introduced to the local ponds in 2011, after employees at Deseret Chemical Depot restored and replanted the ponds with a refuge in mind. The ponds have since changed ownership, but the least chub have continued to thrive under the supervision of Tooele Army Depot to such an extent that Grover said some of the fish could be ready for reintroduction to their native springs in as little as two years.
The least chub, though technically not endangered, is a candidate species that could gain federal protection under the Endangered Species Act within the year, pending a review of the species’ status.
A 2010 decision listed the fish as “warranted but precluded” under the act, meaning federal officials consider the least chub sufficiently threatened to warrant federal protection, but that the species could not be listed officially because of higher funding priorities.
According to federal records, the least chub was considered a moderately high priority for protection because the species is threatened by habitat loss and predation by nonnative species. On a scale of 1 to 12, with one considered the highest possible priority, federal scientists consider the least chub a seven.
Those same records suggest that the least chub’s presence in Utah dates back to ancient Lake Bonneville, and that the species has continued to thrive in peripheral bodies of water — primarily freshwater springs — that remained after the original lake receded. The species is unique to the Bonneville basin and does not naturally exist outside a limited range.
Six populations of least chub still exist, and five of those populations are considered stable by state biologists. However, the population at Mona Springs, which Grover said is so genetically distinct from the other known populations that it could be considered its own species by some measures, has nearly died out.
“Preserving this genetic strain of least chub is pretty important to the survival of the species,” he said.
Mona Springs in Juab County is under siege by mosquitofish, a nonnative species brought to the area to control insects that is rapidly displacing the least chub in some areas. The state has attempted to remove these mosquitofish from Mona, said Krissy Wilson, native aquatics coordinator for the Division of Wildlife Resources, but the invaders proved difficult to eradicate.
The state’s current strategy for saving the least chub involves a network of refuge ponds where the least chub can be protected from invasive species. The species’ conservation plan calls for a minimum of two refuges for each of the six wild populations, but currently there are about 20 sites in the works, Wilson said.
The depot’s refuge is not only a part of this conservation network, but serves as a back-up for Mona Springs, from which the depot’s fish originate. Should the least chub population at Mona fail entirely — federal records argue that the Mona Springs population has already declined to the point that reproduction is no longer viable — wildlife biologists could reboot the springs by introducing fish from the depot.
The depot refuge is an ideal situation for the fish, said Troy Johnson, an environmental representative for the Tooele Army Depot South Area. The refuge consists of two ponds that the chemical depot’s employees rehabilitated with the least chub specifically in mind.
Employees who wished to participate could volunteer an hour at a time to re-line the ponds, which are fed by a natural spring, and then re-plant the area with native plants that would provide food for the omnivorous least chub.
The depot continues to monitor the ponds, checking for intrusions by unwelcome species about once a week, Johnson said. More notably, because there is no public access to the ponds, the fish are protected from the most invasive species of all — humans.
It’s far from the only conservation project the depot has undertook. Using grant money from the federal government, employees there have installed 20 artificial nesting platforms for birds of prey in the area, and also 80 underground nest boxes for the burrowing owl. Both projects are slowly gaining popularity with local wildlife. Eight of the nesting platforms were used this year, and about 20 of the nesting boxes contain active owl burrows, said Johnson.
The fish, although not Johnson’s favorite, are perhaps the most at risk. Their presence on the depot is conditional. If listed, the federal government might impose restrictions that could hinder the depot’s military mission. Consequently, the fish could be removed from the base entirely.
“It would be unfortunate if we couldn’t come up with an agreement to manage those fish here,” Johnson said. “There would be some employees who would be saddened by that, but the mission is the priority.”