Technical Report

Continuing Observations of Rio Grande Silvery Minnow Hybognathus amarus Using a Fish Passage Structure

URL: https://webapps.usgs.gov/mrgescp/documents/Archdeacon%20and%20Remshardt_2012_Continuing%20observations%20of%20RGSM%20Hybognathus%20amarus%20using%20a%20Fish%20Passage%20Structure.pdf

Date: 2012/01/31

Author(s): Archdeacon T.P., Remshardt W.J.

Publication: Prepared for Bureau of Reclamation, 17 p.

Abstract:

Recent research suggests fragmentation of fluvial habitats is a cause of decline of many species of fishes, particularly pelagic-spawning minnows, a reproductive guild characterized by semi-buoyant eggs released directly in the water column. Construction of fish passageways (“fishways”) might help alleviate some effects of barriers on stream-dwelling fishes including Rio Grande silvery minnow. Rio Grande silvery minnow Hybognathus amarus, a federally endangered species, have the physiological capability of long-distance upstream dispersals, and have been documented using model fishways in laboratory trials. However, in-stream use of fishways has not been documented. To determine if Rio Grande silvery minnow would use in-stream fishways, we implanted 6,657 Rio Grande silvery minnows with passive integrated transponders and a used passive scanning station to document movements from seven release locations, up to 19.7 km upstream and 13.5 km downstream of a bypass structure, and to document successful ascension of an in-stream rock channel fishway on the Rio Grande, Albuquerque, New Mexico. Between 18 March, one week after release, and 21 August 2011, 157 individuals were detected (2.4% of total); with 61.1% fish detected upstream release sites and 39.9% from downstream release sites. More than half (60.2%) of detections occurred between 0700 and 1900 hours, suggesting Rio Grande silvery minnow are more active during daylight hours. The number of daily detections was inversely related to discharge (P<0.0001), while distance of each release location to the passageway was not related to the proportion of fish detected from each release location. We conclude Rio Grande silvery minnow can use appropriately constructed fishways which may reduce associated negative impacts of habitat fragmentation in the Middle Rio Grande on Rio Grande silvery minnow.