Determining preferred spawning habitat of the endangered Rio Grande silvery minnow by hydrological manipulation of a conservation aquaculture facility and the implications for management

The endangered Rio Grande silvery minnow (Hybognathus amarus) was induced to spawn in both 2012 and 2013, using hydrological manipulation of a conservation aquaculture facility to create floodplain habitat. Fish responded to the flood by leaving the stream and entered both deep (20–97 cm) and shallow (14–18 cm) low‐velocity off‐channel habitats, spawning in the deep ones; fish did not spawn in the stream. When water level was brought down from flood stage, fry actively moved into the stream 2.5 weeks postspawn. This study supports the hypothesis that this species is a floodplain spawner. The results show that habitat restoration of the Rio Grande to create floodplains is needed for recovery of this species as floodplains are both spawning and nursery habitats. The study provides guidelines about how deep floodplain inundation must inundate for spawning to occur and for the duration of inundation so fry can actively swim with the water when flood waters recede. This project also shows that a conservation facility can be used for all stages of fish's life history. Equally important, it shows that a conservation aquaculture facility can be used to conduct hydrological experiments to determine how an endangered fish will respond to changes in river management.