Stewart Jacks, Assistant Regional Director of Fisheries in our Southwest Region talks about the no-longer-quite-so-grand Rio Grande and our work to conserve this New Mexican fish. If you need a reminder that the Earth is held together by stone, look to the Sandia and Manzano mountains in central New Mexico. Born of what must have been violent tremors, the Rio Grande slices down a natural rift left behind by massive movements of whole plates of planet Earth that birthed these mountains. Where the southern Rockies end, these new and different mountains emerge. From Placitas to El Paso the west face of a long chain of dry crags reveal the past.
In these tilted wedges, the remains of sea-dwelling creatures swim forever entombed in limestone 10,000 feet above sea level. Along this front of friable mountains, few people live. Night skies are inky black and you feel you can still reach out and touch the cosmos rarely concealed by clouds. No clouds—no rain. The sky governs fate in the American Southwest.
The Rio Grande, as grand as it is, is not the river it once was. Despite the remoteness and sparse population, the river has been thoroughly humanized by command of its water. Rio Bravo del Norte, as the river is called in Mexico, has lost its bravado. It is wild and turbulent no more. A river that once flushed with spring snowmelt and summer freshets—pulses of water that told native minnows ”it’s time to spawn”—has been weakened by manmade structures.
A river wide and braided that carved new paths under its own power, as rivers are in the habit of doing, is now rather oddly perched above its own floodplain through long reaches. Under the summer heat, sun and sand may soak it up leaving cakes of mud and pools soon to pass. Fresh sodden spring sediment rich with ripe cottonwood seeds that regenerate mosaics of riparian woodlands are historic artifacts as prickly water-sucking non-native trees now dominate the depleted river’s rigid course.
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| Rio Grande silvery minnow.
Photo by Jason Remshardt/USFWS |
The Rio Grande still has water and fish need water—that’s a given. But a hospitable habitat for a fish is much more than a wet place. Water alone does not constitute an environment suitable for fish. And perhaps that’s most readily apparent in the plight of the Rio Grande silvery minnow, an endangered species that hangs on in a vestige of its once-expansive range.
The minnow that shines like sterling is as much New Mexican as are the mountains that frame what is left of its habitat. To thrive, the minnow needs a mix of slow-moving shallows as nursery habitats and steady mainstream flows in maturity to grow and spawn. Until there is reliable habitat, U.S. Fish and Wildlife Service field stations must fill in the gaps. It’s our job to see that this piece of our natural heritage persists into the future, no matter how expansive and how contentious. Last month, our Southwestern Native Aquatic Resources and Recovery Center in Dexter stocked 38,000 Rio Grande silvery minnows near Socorro. Weeks earlier, the Dexter facility moved 83,618 minnows to the Rio Grande in Big Bend National Park, adding to the 132,000 minnows stocked there from Uvalde National Fish Hatchery.
The challenge is large. Captive-rearing this New Mexican fish buys time to figure out what needs fixing in nature. The minnow’s situation is a marker for a larger conservation concern brought about by a river fully commanded by human need.