It is a pre-meditated killing, cold-blooded in every sense. Before night descends, the conspirators make final calculations. The next morning, they return with the lethal poison. Hundreds die, but to one federal agency their deaths are not in vain – the victims are non-native fish, taken out by the U.S. Fish and Wildlife Service as part of its recovery efforts for native Apache trout in east-central Arizona.

Those efforts are now close to reeling in the ultimate trophy catch: the delisting of a threatened fish. Historically, extinction is the only circumstance under which a fish species has been removed from federal protection. But now, barring a natural disaster such as fire or drought, the Apache trout will be the first fish delisted as a result of successful recovery. Over the last five decades, Apache trout conservation efforts have aimed to repair habitat damage caused by Arizona’s early economic development. In the early 1900s, land-use methods altered the trout’s pristine coldwater habitats and sank its population levels. Livestock grazing and logging removed vegetation that stabilized and shaded stream banks, while sand and gravel mining triggered erosion. Water temperatures increased and fewer mayflies and caddis flies – the trout’s preferred food – hatched out.

During the same era, state and federal wildlife agencies stocked the White Mountains’ high-elevation streams and lakes with non-native species to increase fishing opportunities. The newly stocked trout – rainbow, brook, cutthroat and brown – out-competed the native Apache trout for food and cover, nearly wiping out Arizona’s official state fish. Genetically similar rainbow and cutthroat also cross-bred with the Apache, an olive-yellow trout with a golden belly and black band through the eye.

In the 1940s, the White Mountain Apache Tribe recognized that the only pure populations of Apache trout in the world lived in highland streams on its reservation, and in 1955, the tribe closed those waterways to sport fishing and helped develop tribal, state and federal recovery plans. Federally listed as endangered in 1967, the Apache Trout was downgraded to threatened eight years later, after conservation efforts brought its numbers up.

Before the trout can be completely delisted, 30 pure self-sustaining populations must be established within historic habitat. The first step in starting a new population is the poisoning of non-native fish with antimycin A. This chemical removes more than fish – it also kills amphibians, crustaceans and aquatic insects. Next, artificial barriers are constructed at stream headwaters where needed to keep non-native fish from returning. Apache trout are then transplanted from relict wild or pure hatchery populations. The fish must display successful spawning patterns before they can be designated as an established population.

After nearly becoming history, the Apache trout is now poised to make it. Twenty-six populations have been established and the remaining four should be stocked by early next year, says Stewart Jacks, Fish and Wildlife project leader. Once recovery goals are met, delisting could occur as early as July 2009.

Although recovery efforts have been successful thus far, official delisting remains an uphill battle. “We’re working on it all the time, and it seems as though progress is two steps forward and one step backwards,” says John Singley, board member of Trout Unlimited’s Old Pueblo Chapter. “But we’re climbing the ladder.”