Endangered Species Spotlight: The Silvery Minnow of the Rio Grande River

The Rio Grande is an important river in the southwestern United States. It provides water for domestic uses, agriculture, industry and power. The river has been harnessed, and its energy put to work for humans. Unfortunately, all of the good the river does in these areas comes at a cost.

The silvery minnow, a native to the Rio Grande, used to live in the river from northern New Mexico all the way to southern Texas. It is a food source for birds and other predators in the river. Following the construction of several dams on the river and its tributaries in the 1960s and 1970s, the silvery minnow's range was significantly decreased. To add insult to injury, non-native fish were introduced to the river system that further hindered the silvery minnow. Ultimately, it would be limited to a stretch roughly two-thirds the north to south length of the state of New Mexico. This led to the Rio Grande silvery minnow being listed on the endangered species list in 1994.

Six years after this listing, no silvery minnow eggs were produced in the wild. Scientists at New Mexico State University in the Fish, Wildlife and Conservation Ecology department started breeding the fish indoors, using geothermally heated water. The fish thrive in their greenhouse homes with naturally warm water, and grow to sizes not observed in the wild. The Rio Grande silvery minnows can breed year round under these conditions. Eventually, fish larva are sent to federal facilities where they grow until big enough to be released into the wild. You can watch a 12 minute video on silvery minnow breeding and research being conducted at New Mexico State University by clicking here.

Because of the Endangered Species Act, a specific amount of water must kept in the river to maintain suitable silvery minnow habitat. Water rights are a valuable commodity in the arid region, and government's are leasing water from farmers to maintain this habitat. This type of scenario is popping up all over the country, where there is an endangered fish in the river. It is essential that we try to understand these species in order to maintain a healthy ecosystem, which we rely on to survive.

References:

D.E. Cowley et al. Ecology of the Rio Grande Silvery Minnow (Cyprinidae: Hybognathus amarus) Inferred from Specimens Collected in 1874. Reviews in Fisheries Science, 14, 2006

High Plains Journal. Utility plans to buy water from farmers to sustain Rio Grande. 3/8/2007