Keeping the Rio Grand: Saving Rio Grande Silvery Minnow

Authors: Thomas Archdeacon, Tracy A. Diver, Tristan J. Austring, Matt S. Nolan

Year: 2013 (xlv)

Abstract

The Rio Grande silvery minnow, Hybognathus amarus, was listed as endangered under the Endangered Species Act (1973, as amended) in 1994. Historically, the fish was widely distributed throughout the Rio Grande and Pecos River. It currently occupies less than 10% of its historic range. Population decline of the Rio Grande silvery minnow (RGSM) within the Rio Grande has been directly related to altered flow regimes caused by dam construction and operation, and concomitant habitat degradation. During summer months, increased water needs require large amounts of water to be diverted from the Rio Grande, causing large sections to of the river to dry. Beginning in 2001, salvage efforts were implemented to remove RGSM from isolated pools in intermittent sections of the river as part of a strategy to minimize take of the species. Daily water management notification to U.S. Fish and Wildlife Service personnel identify when and where sections of the river are projected to dry. Isolated pools in drying reaches are then seined for RGSM. Fish collected from the pools are then transported in fiberglass transport tanks and moved on utility terrain vehicles to reaches of the Rio Grande River with continuous flow, if the fish meet minimum health standards. In 2013, 36.1 unique river miles were salvaged. A total of 1,149 RGSM were successfully rescued, and 343 were not transported due to death or compromised health. Since 2007, salvage efforts have continued to increase; however, rescue success has declined with overall abundance of RGSM. Salvage is an attempt to reduce mortality; however, it is no substitute for maintaining water in the river. Fish need water to live.