Publication Technical Report
Rio Grande Silvery Minnow Population Monitoring During 2018
URL: https://webapps.usgs.gov/mrgescp/documents/3a_2018-RGSM-Population-Monitoring-Final.pdf
Date: 2019/04/29
Author(s): Dudley R.K., Platania S.P., White G.C.
Publication: Prepared for U.S. Bureau of Reclamation, 193 p.
Abstract:
As part of the Rio Grande Silvery Minnow Population Monitoring Program, the status of this imperiled species and the associated Middle Rio Grande ichthyofaunal community has been systematically monitored since 1993. This effort is unique among ichthyofaunal research studies in the Middle Rio Grande in that it has been providing consistent sampling of fishes over a very long duration. Long-term sampling studies also provide the data necessary to test specific ecological hypotheses. Our primary research objective was to evaluate how seasonal and annual changes in river flows affect the distribution and abundance of Rio Grande Silvery Minnow throughout its current range.
The occurrence and density of Rio Grande Silvery Minnow has fluctuated widely over the past two decades (1993–2018). While its estimated density (E(x); fish per 100 m2 ), using October data, was notably higher from 2016 to 2017 as compared with 2010 to 2015, there was a marked decline in 2018. Population monitoring efforts in 2018 revealed a greatly reduced density of Rio Grande Silvery Minnow (0.09), which represented a 99.6% decline from 2017 (23.17). While Rio Grande Silvery Minnow represented 35.7% of the total fish community in 2017, it had decreased to < 0.2% by 2018.