by Sandra AvantThis sidebar appeared in the Spring 1997 issue of New Mexico Resources, as an adjunct to the article "Wild New Mexico".
Photograph by Paul Turner
Biological relics, tiny pupfish thrive in desert waters where other fish literally would be found dead. They endure waters of high salinity - three times saltier than sea water - and can survive temperatures ranging from near freezing to scorching hot.
"Pupfish are extremely tolerant of what's considered poor water quality for humans and other types of fish," says Paul Turner, assistant fishery and wildlife sciences professor at NMSU. "They are highly tolerant of low oxygen, and can subsist in temperatures above 100 degrees."
Pupfish are widespread throughout the Southwest and northern Mexico, he says. In New Mexico, only two types of pupfish currently exist - the White Sands pupfish and the Pecos pupfish. The White Sands species, unique to the Tularosa Basin, differs from the Pecos species found in saline springs and gypsum sinkholes on Bitter Lake National Wildlife Refuge, Bottomless Lakes State Park, and desert streams along the Pecos River.
The males of both species glow a brilliant purplish or iridescent blue when breeding, but the White Sands pupfish becomes even more colorful with splashes of bright yellow and orange on their fins. The Pecos pupfish breeding males have dusky-black fins. Not as vibrant, the brownish to greenish females have dark lateral bars that expand into scattered blotches on their lower sides.
"Pupfish are species that have been isolated oftentimes in desert environments," Turner says. "The White Sands pupfish apparently reached the basin via a prehistoric tributary of the Pecos River. They once were more widespread when the Pleistocene Lake Otero occupied much of the basin. When the waters receded, pupfish retreated to the few remaining suitable habitats."
Despite desiccation, an increase in salinity, and extreme heat associated with the harsh environment, the resilient pupfish persevered.
Although not listed by the federal government as endangered or threatened, the New Mexico's game and fish department, White Sands Missile Range, U.S. Fish and Wildlife Service, White Sands National Monument, and Holloman Air Force Base have agreed to protect the White Sands pupfish to ensure its survival. Dangers to the species include water withdrawal from pupfish habitat, pollution, and competition from non-native fish. Part of the plan involves tracking populations and eradicating non-native fish from pupfish dwellings.
"Most pupfish habitats are probably too salty for other fish to survive," Turner says. "However, there are a couple of spring-fed habitats in which other non-native fish like bass could survive and threaten pupfish in those areas."
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