Technical Report
Rio Grande Silvery Minnow Augmentation in the Middle Rio Grande, New Mexico Annual Report 2006
Date: 2008/06/12
Author(s): Remshardt W.J.
Publication: Report prepared for the U.S. Bureau of Reclamation, 70 p.
Abstract:
In response to declining distribution and abundance, New Mexico Fish and Wildlife Conservation Office have released nearly 1,000,000 hatchery-raised Rio Grande silvery minnow into the Rio Grande since 2002.
In 2006, a total of 418,851 Rio Grande silvery minnow were released into the Middle Rio Grande, New Mexico. Along with favorable spring snowmelt flows for spawning and recruitment in 2004 and 2005, these efforts corresponded to increased catch rates of young-of-year Rio Grande silvery minnow initially in the Angostura Reach where augmentation began in 2002, and now in Isleta and San Acacia as augmentation efforts have expanded to the entire range of Rio Grande silvery minnow below Angostura Diversion Dam.
There were a total of 8,375 Rio Grande silvery minnow collected between January and December 2006, including 298 positively identified as hatchery-released.
Results indicate that hatchery raised individuals can be released to the wild with over 90% retention within 10 miles of original release sites and can experience survival of at least 1 year after release.
In 2006, we continued augmention efforts throughout the current occupied range of Rio Grande silvery minnow, with releases in all three reaches.
Lower recapture, survival, and growth rates in 2006 compared to 2003-2005 suggest that augmentation may be less effective at higher base Rio Grande silvery minnow densities.