The Gila Bioregion is literally teeming with wildlife including its top carnivore the Mexican gray wolf, and also many endemic species such as the Gila trout, Apache trout and Chiricahua leopard frog. Unfortunately, due to a century of overuse by cattle and loggers combined with an uncanny dedication by the federal government to the eradication of wolves and wildfire, many of the native wildlife are imperiled and require the protective designation of the Endangered Species Act. The Mexican spotted owl, the Gila chub, spikedace, loach minnow, southwestern willow flycatcher and jaguar are just a few of the federally protected species that occur in the region.
The Gila trout, downlisted to threatened in 2006, is endemic to five streams in the upper Gila River system. Currently, there are 14 populations of Gila trout in the wild. Found in small, high mountain streams at an elevation of approximately 1,524 to 3,048 m (5,000 to 10,000 ft). The trout feeds on insects and occasionally small fish. Population declines are attributed to erosion, sedimentation, predation by and competition and hybridization with nonnative fishes. Gila trout will be considered for delisting when: 1) at least 20 populations in the Gila River Recovery Unit are established in at least 150 km (93 mi) of stream; 2) at least 15 populations in the San Francisco River Recovery Unit are established in at least 80 km (50 mi) of stream; and 3) at least four San Francisco-Gila River mixed lineage populations are established in at least 40 km (25 mi) of stream.
The Apache trout is the state fish of Arizona, and along with the Gila trout is one of only two species of trout native to that state. The Apache trout was listed as
Endangered in 1967 but the species was downlisted to threatened in 1975 after successful culturing in captivity and a greater knowledge of existing populations.
The original listing of the Apache trout occurred as a result of the decrease of the species’ distribution and population levels, primarily because of habitat alterations and negative interactions with non-native salmonids. Land-use practices including logging, livestock grazing, reservoir construction, agriculture, and road construction also caused damage to Apache trout habitat.
The Apache trout historically occurred in Arizona in the upper Salt River division of the Gila River basin, in the headwaters of the Little Colorado River watershed, and in the Blue River of the San Francisco River watershed. The trout has suffered a 95% reduction in range due to hybridization with rainbow trout and competition with brook and brown trouts. It is now limited in the Gila Bioregion to a small number of tributaries in the White Mountains. According to the USFWS, when the recovery criteria and site-specific management actions are met, pure Apache trout will exist in at least 30 populations in approximately 275 kilometers (km) (171 miles) of secured stream habitat.