(CN) — The U.S. population of Mexican wolves in the wild grew by one last year, from 113 to 114, according to the U.S. Fish and Wildlife Service, far fewer than the 750 wild wolves that environmentalists say are needed to sustain the species.
The Mexican wolf is the rarest subspecies of gray wolf in North America. Once common in the Southwest United States and Mexico, it was all but eliminated from the wild by the 1970s.
The Fish and Wildlife Service began a captive breeding program in 1977, and in 1998 released the first captive-bred Mexican wolves into the wild in Arizona and New Mexico. More Mexican wolves were released into the wild in Mexico in 2011.
The Mexican Wolf Recovery Plan, completed in November 2017, seeks a recovery population goal of 320 wolves.
While Fish and Wildlife said the static population is disappointing, it said population growth is not the only indicator of the program’s success.
“While the 2017 numbers are not what we were hoping for, this is not the sole metric to measure progress in Mexican wolf recovery. The fact that cross-fostered wolves had pups this year is a major milestone and presents a mechanism to better manage genetics,” Arizona Game and Fish Department official Jim deVos said in a statement.
“Also encouraging is the substantial increase in the number of Mexican wolves that were equipped with monitoring collars that will greatly increase the management information that the (Interagency Field Team) collects.”
But the Tucson-based Center for Biological Diversity called the flat-lining population a result of mismanagement by Fish and Wildlife.
“This stagnation in numbers is troubling because the Mexican gray wolf faces so many challenges to recovery that every individual’s survival counts,” Center for Biological Diversity spokesman Michael Robinson said in a statement.
“This is a warning bell, that the Fish and Wildlife Service needs to release more captive animals to increase the health of the wild population.”
The Center for Biological Diversity and others sued Fish and Wildlife in January, claiming that its Mexican Wolf Recovery Plan was not supported by the best available science. They said the plan calls for releasing an insufficient number of captive wolves to ensure genetic diversity and population growth in the wild, and that a minimum of 750 wolves, not 320, are needed to provide the species the best chance for recovery.
“Mexican wolves urgently need more room to roam, protection from killing, and more releases of wolves into the wild to improve genetic diversity, but the Mexican wolf recovery plan provides none of these things,” plaintiffs’ attorney Elizabeth Forsyth, with EarthJustice, said in a statement.
Fish and Wildlife documented 12 wolf deaths and 10 wolves removed from the wild in 2017, while 26 pups survived to the end of the year, down from 50 surviving pups in 2016.