Rio Grande silvery minnow
| Rio Grande silvery minnow | |
|---|---|
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cypriniformes |
| Family: | Cyprinidae |
| Genus: | Hybognathus |
| Species: | H. amarus |
| Binomial name | |
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Hybognathus amarus (Girard, 1856) |
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The Rio Grande silvery minnow or Rio Grande minnow (Hybognathus amarus) is a small herbivorous North American fish. It is one of the seven North American members of the genus Hybognathus, in the cyprinid family.
The Rio Grande silvery minnow is one of the most endangered fish in North America, according to the U. S. Fish and Wildlife Service (USFWS). They were classified as endangered in the U.S. in 1994, and now are found in less than 5 percent of their natural habitat in the Rio Grande. Historically, the minnow was found from Española, New Mexico, to the Gulf of Mexico in Texas. Now it can only be seen between the Cochiti Dam and the Elephant Butte Reservoir.
It is a stout silvery minnow with moderately small eyes and a small mouth. Adults may reach 3.5 inches in total length.
Rio Grande silvery minnows are herbivores whose diet is believed to consist of river plants and benthic macroinvertabrates, though there is little research into their diet due to the difficulty of getting into their stomachs. They play a role in keeping water clean by eating bad algae.
Silvery minnows tend to skim the bottom of rivers and stream, and are prolific spawners. They serve as food source for other animals.
The Rio Grande Silvery Minnow's eggs hatch in about 24 hours into larvae that can swim in just 3 to 4 days. It is no surprise that a species so programmed for survival once dominated a biological niche that spanned 3,000 meandering miles (4,825 kilometers) from New Mexico to Texas.
The Rio Grande silvery minnow was first listed on July 20, 1994. It is currently designated as Endangered in the Entire Range. The population decline of the Rio Grande Silvery Minnow has been almost directly proportional to recent alterations to the Rio Grande over the past century. There have been multiple diversions for municipal and agricultural use; alteration of the natural hydrograph (no spring runoff to cue spawning); habitat degradation from river narrowing and canalization; and construction of diversion dams which prevent migration. Even with the Rio Grande Silvery Minnows listing in 1994, its population has continued to drop at a great rate. The minnow now numbers way below its 1994 population, and is found in only 5 percent of its former habitat.
In 2000, the U.S. Fish and Wildlife Service initiated a silvery minnow egg salvage pilot project. Biologists from the Service, Bureau of Reclamation, and University of New Mexico collect minnow eggs as well as reproductively-ready adult minnows near Elephant Butte, where these efforts do not disturb upstream populations. Captured adult minnows are induced to spawn, either at the Albuquerque Biological Park or the Service's New Mexico Fishery Resources Office. Biologists then either return the resulting fish to the Rio Grande or hold them for captive propagation.
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Wikipedia