Technical Report
Rio Grande Silvery Minnow Rescue and Salvage - 2009
Date: 2010/11/04
Author(s): Remshardt W.J.
Publication: Prepared for U.S. Bureau of Reclamation, 36 p.
Abstract:
This report documents efforts during 2009 to reduce the mortality of post-larval Rio Grande silvery minnow (RGSM, Hybognathus amarus) when flow in the Middle Rio Grande became intermittent. In January of 2007, New Mexico Fish and Wildlife Conservation Office (NMFWCO) assumed responsibility for salvage operations for RGSM. Initially, we formulated a new salvage protocol to more effectively manage the salvage activities. This included defining criteria for how and when salvage of RGSM would occur. These criteria were defined using field experience (regarding air temperature and secondary fish health), and review of tolerances of RGSM to environmental variables developed by K. Buhl, USGS Ecotoxicology Research Center in Yankton, South Dakota. Handling and transport protocols initiated in 2007 based on research conducted by Dr. Colleen Caldwell, New Mexico State University, were continued in 2009. Results indicate that efforts undertaken in 2007 improved survival of RGSM that had been subjected to poor habitat and water quality conditions during intermittency and handling during salvage.
Between 16 July and 20 October 2009, a total of 20.0 miles of the main channel of the Middle Rio Grande dried, all in the San Acacia Reach. An estimated total of 18,473 RGSM were salvaged from isolated pools in 2009. Of these, 17,199 were transported and released alive within flowing sections of the San Acacia Reach. The death of 1,694 RGSM was attributed to water operations in the Middle Rio Grande during the 2009 irrigation season and assigned as incidental take. This level of observed incidental take was well below the limits established under the amended Biological Opinion of 22,242 individuals. The death of 1,646 RGSM was attributed to U.S. Fish and Wildlife Service permit activities.