Native fish conservation and management in the upper/middle Rio Grande, Pecos River, Canadian River, Tularosa and Guzman basins, New Mexico during 2010.

Authors: W. Jason Remshardt, Stephen R. Davenport, Robert K. Dudley, Steven P. Platania, David L. Propst

Year: 2010 (xlii)

Abstract

Native fish conservation in New Mexico is accomplished through long term monitoring of protected species, captive propagation, stream restoration, and interagency water management. Long term monitoring and research programs track many rare native desert fishes including Rio Grande silvery minnow (Hybognathus amarus) in the Rio Grande, New Mexico, and Pecos bluntnose shiner (Notropis simus pecosensis) in the Pecos River, New Mexico. In 2010, the revised Recovery Plan for Rio Grande silvery minnow was finalized. Multiple research and monitoring projects for Rio Grande silvery minnow continued in 2010 including population monitoring, population estimation, reproductive monitoring, and fish passage monitoring. For population monitoring, the most recent data available is from 2009. Mean October densities (#/100m2) of Rio Grande silvery minnow collected from 20 sites in the Middle Rio Grande, NM were not significantly different in 2009 (M=16.15, SD=19.07) as compared to 2008 (M=8.32, SD=7.42). However, low flows and river drying (July-September) appear to be negatively impacting the population in 2010. Since 2006, population estimates have been used as an additional resource to standard monitoring for management. Reach-specific population estimates of Rio Grande silvery minnow in 2009 were highest in the Isleta Reach (N=1,602,348 ± 457,764) and lowest in the San Acacia Reach (N=923,352 ± 568,776). The total population estimate for all reaches combined was 3,476,873 ± 918,779 representing an increase from the 2008 estimate of (N = 2,283,790 ± 740,860.73). Estimates of the probability of extinction were relatively low for age-0 individuals (0.0486) but higher for age-1 and age-2 individuals (0.1750 and 0.1234, respectively), based on site occupancy estimates from 2005 to 2009. Analysis of Rio Grande silvery minnow reproductive output in the San Acacia Reach revealed a significant difference (F=6.36; p<0.0001) among mean values of catch rate (#/100m3) for the eight years of the study (2002-2004, 2006-2010), including a significant decline (p<0.05) from 2007 to 2010. The number of eggs estimated to be transported downstream of the San Acacia Reach site (just upstream of Elephant Butte Reservoir) during the 2010 study was 500,755 with a daily maximum of 217,576. United States Fish and Wildlife Service (USFWS) continued monitoring of a rock channel fish passageway constructed in 2008 for Rio Grande silvery minnow. PIT-tagged Rio Grande silvery minnow were released at various locations upstream and downstream of the passage in 2009. Rio Grande silvery minnow were documented moving upstream >10 km from release locations, as well as documenting their ability to move upstream in a rock channel fish passageway. Future work will include additional release of PIT-tagged fish to document specific pre-spawn movements of adult fish. United States Fish and Wildlife Service and U.S. Bureau of Reclamation in 2010 began working on phase II of Pecos River restoration to improve habitat for native fishes including Pecos bluntnose shiner. Phase I was completed in 2009 at Bitter Lake National Wildlife Refuge where an isolated river meander was reconnected to flow. Phase II will restore an additional 1.5 river miles downstream of Phase I. In association with this restoration, USFWS began a pilot project in 2010 to monitor the effectiveness of river restoration in creating larval fish habitat in low-velocity habitats.