Publication

Design Improvements for Constructed Rio Grande Silvery Minnow Nursery Habitat

URL: https://webapps.usgs.gov/mrgescp/documents/Massong%20et%20al._2004_Design%20Improvements%20for%20Constructed%20RGSM%20Nursery%20Habitat.pdf

Date: 2004/09/01

Author(s): Massong T.M., Porter M.D., Bauer T.

Publication: U.S. Bureau of Reclamation Report, 26 p.

Abstract:

For the last two years, the Albuquerque Area Office of the Bureau of Reclamation has lead several efforts to restore habitat along the Rio Grande in New Mexico for the endangered Rio Grande silvery minnow (Hybognathus amarus) (silvery minnow). This species was federally listed as endangered in 1994 (U.S. Department of the Interior 1994). Critical habitat was designated for the species along with portions of the Rio Grande in New Mexico in 2003 (U.S. Fish and Wildlife Service 2003). Loss of suitable habitat is thought to be the main contributing factor in the decline of the silvery minnow in the Rio Grande (Bestgen and Platania 1991). A main goal of this project is to increase Reclamation’s understanding of silvery minnow habitat needs and to improve our ability to construct suitable habitat, especially habitat for the egg/larval lifestage (nursery habitat). This report summarizes potential design improvements for constructing nursery habitat. This research uses a landscape ecology approach (Forman 1995) to evaluate habitat and life history needs for the silvery minnow. Channel incision resulting from upstream dams has isolated floodplain habitat during years with reduced runoff discharge (Porter and Massong 2005). The importance of edge habitat along the river bank for fulfilling critical life history components of the silvery minnow has not received much attention. In previous studies, we documented that constructed inlets adjacent to the main flow in the channel retained silvery minnow eggs and attracted a variety of free-swimming fish. The primary features in successful inlets for egg retention appeared to be both the formation of a ‘drift zone’ within the inlet, but also substantial inflow and outflow at the inlet mouth (Figure 1). The drift zone is defined as the inundated area with an un-measurable low water velocity that occurs farther back in the inlet.