Exploratory Analysis of Hydrograph Parameters for Rio Grande Silvery Minnow Spawning, Recruitment, and Population Viability

The Rio Grande silvery minnow (Hybognathus amarus) was a formerly widespread endemic fish species, now restricted to 170 miles of the Rio Grande in New Mexico. Water management on the Rio Grande over the past 100 years has changed the hydrology and channel geomorphology. Inundated floodplains provide spawning and nursery habitat for many fish species, including silvery minnows. Water management and drought have reduced the magnitude of the spring snowmelt hydrograph and the associated connectivity between the river and the floodplain. The availability of inundated floodplain habitat can have important implications for fish reproduction, recruitment, and population viability.

The objective of this study is better understand annual silvery minnow spawning and recruitment in response to environmental flow parameters. A functional data analysis approach using R statistical software was used to identify the relative hydrograph parameters (magnitude, frequency, duration, timing, rate-of-change) associated with increased silvery minnow recruitment rates and population indices. This analysis will support adaptive management by refining recruitment flow parameters for better informed water management strategies.