WATER, ENDANGERED FISHES, AND DEVELOPMENT PERSPECTIVES IN ARID LANDS OF MEXICO

Nearly half of Mexico is and or semiarid, with scarce waters. At least 92 springs and 2500 km of river have dried in this area Surface water s have diminished, and phreatic waters are sinking deeper, provoking i ntrusion of saline waters and salinization of agricultural wells in So nora, reversing phreatic circulation in the Comarca Laguenera, allowin g arrival of arsenic to agricultural waters, and threatening metropoli tan Torreon. There are nearly 200 species of freshwater fishes in this region, 120 under some threat, 15 extinct through human impact. As of 1985, an average of 68% of species was eradicated in local fish fauna s. Finally, salinization of the lower Rio Bravo del Norte has replaced 32 native fish of fresh or slightly brackish water with 54 mainly mar ine or highly salt-tolerant species; the salinization threatens all us es of water. Some marine fishes invade up to 400 km upstream. Pollutio n is strong, and fish kills have been reported. These low-quality and scarce waters comprise future resources for cities such as Monterrey, which, along with its border twin cities, is expected to double its hu man population by 2010. Redesign of regional development is urgently n eeded, in keeping with the real availability of water. All water use s hould be equal to or less than lower recharge averages; norms of integ ral basin management should rely on criteria of high-use efficiency, r ecuperation, recycling, and reutilization. Also necessary are reduced pollution and increased treatment of residual waters. Innovative envir onmental vision is especially essential in light of expectations for d evelopment through the North American Free Trade Agreement, the Border Integral Environmental Plan, industrial expansion, and the modernizat ion and internationalization of the northern Mexican border belt. Thes e all conflict with the high priori recently decreed for species conse rvation by the Mexican Act, creating the National Committee on Knowled ge and Use of Biodiversity.