Technical Report

Fish Community Monitoring and Sampling Methodology Evaluation: Task 4 Report - Comparison of Methods Used to Sample the Middle Rio Grande Fish Community and the Endangered Rio Grande Silvery Minnow - Final Study Results

URL: https://webapps.usgs.gov/mrgescp/documents/Gonzales%20et%20al_2012_Fish%20Community%20Monitoring%20and%20Sampling%20Methodology%20Evaluation%20Task%204%20Report%20Comparison%20of%20Methods%20Used%20to%20Sample%20the%20MRG%20Fish%20Community%20and%20the....pdf

Date: 2012/09/01

Author(s): Gonzales E., Widmer A.M., Burckhardt L.L.

Publication: Prepared for U.S. Bureau of Reclamation. Prepared by SWCA Environmental Consultants, 166 p.

Abstract:

This fish community monitoring and sampling methodology evaluation study was designed to identify, evaluate, and validate sampling gear types that may be used to monitor the Middle Rio Grande fish community. Particular emphasis is placed on estimating abundance and characterizing the length structure of the Rio Grande silvery minnow (Hybognathus amarus; silvery minnow) on floodplains and side channel habitats during spring runoff and in the main channel during pre-runoff and fall base flow periods in the Middle Rio Grande, New Mexico. The study was funded by the Middle Rio Grande Endangered Species Collaborative Program (Collaborative Program) and coordinated by the U.S. Bureau of Reclamation with technical guidance from the Science Workgroup of the Collaborative Program.

Samples were collected from different habitats (i.e., main channel, floodplain, and side channel) and during different seasons (i.e., before spring runoff, during spring runoff, and during fall baseflow) in 2010, 2011, and 2012 to compare backpack electrofishing, beach seine, fyke net, and bag seine catches under different environmental conditions. Primary study objectives include using a paired gear approach to assess the relative efficiency of commonly used gear types in floodplain and main channel habitats for 1) monitoring the Middle Rio Grande fish community, 2) determining the silvery minnow population length structure, and 3) monitoring the relative abundance of silvery minnow. Results collected during the study indicate that the relative efficiency of gear types for sampling the Middle Rio Grande fish community and the silvery minnow varies among gear types depending on the parameter measured (e.g., species richness, detection, relative abundance, silvery minnow size), habitat sampled (i.e., floodplain, main channel), and time of year.