Developing a Habitat Quality Metric for Assessing Climate Change Impacts for Warm Water Fish Nursery Habitat

The Rio Grande silvery minnow (Hybognathus amarus) is an endangered warm-water fish whose life history requirements are poorly understood. Because habitat management is an important component for species recovery, there is a need for habitat metrics that track the relationship between the hydrologic regime, climate, and population.

The silvery minnow has two observed spawning patterns during spring runoff. The first pattern is spawning in response to low magnitude pulses that produce numerous eggs drifting in the river current. At higher magnitude pulses, silvery minnows spawn on the inundated floodplain. Examination of mesohabitat availability as a function of spring runoff magnitude was conducted to identify factors influencing the spawning response and survival in the river channel versus on the adjacent floodplains. A population model that incorporates long-term mesohabitat availability in response to hydrograph changes is described, and implications for conservation management strategies are discussed.