Technical Report
Rio Grande Silvery Minnow Salvage - 2012 Annual Report
Date: 2012/01/01
Author(s): Remshardt W.J., Archdeacon T.P.
Publication: Prepared for U.S. Bureau of Reclamation, 32 p.
Abstract:
Between 16 June and 22 October 2012, 51.0 unique miles of the main channel of the Middle Rio Grande became intermittent, with 19.2 miles in the Isleta reach and 31.8 miles in the San Acacia reach. A total of 5,014 Rio Grande silvery minnow (RGSM) was observed from isolated pools. Of these, 4,251 were transported and released alive at a location with flowing water within the same reach. The take by mortality observed was 304 Rio Grande silvery minnow and attributed to water operations in the Middle Rio Grande during the 2012 irrigation season (under the 2003 Biological and Conference Opinions on the effects of the Bureau of Reclamation’s Water and River Maintenance Operations, Army Corps of Engineers Flood Control Operation, and related Non-Federal Actions on the Middle Rio Grande). The level of estimated incidental take (observed multiplied by 50) was 15,150 Rio Grande silvery minnows for 2012, and was well below the limits established under the determination of incidental take for the 2012 irrigation season of 396,146 individuals. The mortality of 463 additional Rio Grande silvery minnow was attributed to U.S. Fish and Wildlife Service permit activities. Going into the 2012 salvage season, lower pre-salvage catch rates meant that the allowed Incidental Take number was set lower in 2012 than 2011. Although we salvaged more miles and days in 2012, the number of fish observed both alive and dead was lower in 2012 compared to 2011, a similar trend is seen each year from 2007-2012. Each subsequent wetting and drying with each reach resulted in fewer salvaged Rio Grande silvery minnow per mile, finally resulting in local extirpation in dried areas.