Publication
Rio Grande Silvery Minnow Population Monitoring During April 2018
Date: 2018/05/15
Author(s): Dudley R.K., Platania S.P., White G.C.
Publication: Prepared for U.S. Bureau of Reclamation, 34 p.
Abstract:
The April population monitoring efforts were conducted at the 20 standard sites and at 10 additional sites. Ten sites were located in each of the three sampling reaches: Angostura, Isleta, and San Acacia. The Middle Rio Grande Endangered Species Collaborative Program requested that the additional sampling be conducted once in the spring and fall of each year. While this report follows the typical monthly report format, key changes to the text, tables, and figures are highlighted in bolditalic font. For April 2018, comparisons were made between standard sites and all sites (i.e., standard plus additional sites). For the 2018 monthly trends, data were based on all sites (i.e., standard, additional, and replacement sites) to maintain consistency across all monthly reports. A list of all collection localities is appended (Appendix A). Adult and juvenile fish were obtained by rapidly drawing a 3.1 m x 1.8 m small mesh (ca. 5 mm) seine through discrete mesohabitats. Larval fish were also collected with a 1.0 m x 1.0 m fine mesh (ca. 1.5 mm) seine. All fishes were identified to species and enumerated. We used length-age relationships to assign ages (i.e., age-0, age-1, and age-2+) to all Rio Grande Silvery Minnow collected. Age-0 individuals are, however, only present after annual spring spawning occurs (ca. April–June). Figures illustrating fish densities (i.e., fish per 100 m2) were prepared for the ten focal species to facilitate comparisons across reaches.