Technical Report

Movement Patterns of RGSM Hybognathus amarus, in the San Acacia Reach of the Rio Grande During 2002

URL: https://webapps.usgs.gov/mrgescp/documents/Platania%20et%20al._2003_Movement%20patterns%20of%20RGSM%20Hybognathus%20amarus%20in%20the%20San%20Acacia%20Reach%20of%20the%20Rio%20Grande%20during%202002.pdf

Date: 2003/06/10

Author(s): Platania S.P., Farrington M.A., Brandenburg W.H., Gottlieb S.J., Dudley R.K.

Publication: Report prepared for U.S. Bureau of Reclamation, 31 p.

Abstract:

Rio Grande silvery minnow, Hybognathus amarus, was, historically, relatively widespread and abundant in the Rio Grande occurring from near Española, New Mexico, to the Gulf of Mexico. Recent studies in the Rio Grande basin documented the loss of this taxon upstream of Cochiti Dam and downstream of Elephant Butte Reservoir. The 90-95% reduction in the range of Rio Grande silvery minnow and threats to its continued persistence in the Middle Rio Grande resulted in the listing of this endemic cyprinid as a federal endangered species in 1994. The restriction of Rio Grande silvery minnow to a 279.8 km reach of river between Cochiti Dam and Elephant Butte Reservoir and fragmentation of that range into four segments (35.9, 65.2, 85.5, and 90.4 km long) due to diversion dam structures (Angostura, Isleta, and San Acacia) pose additional threats to the species. Among current proposals designed to aid in the recovery of Rio Grande silvery minnow is removal or redesign of the aforementioned three Middle Rio Grande diversion dams. Prior to any such modifications additional understanding of the autecology of silvery minnow are required. This includes information on home range, distance traveled, and schooling behavior of Rio Grande silvery minnow. In addition, data need to be generated regarding efficacy of marking techniques.

In November and December 2001, approximately 12,000 captive reared Rio Grande silvery minnow ranging in length from 15 mm to 65 mm SL, were marked as part of a project that began as a pilot study designed to evaluate the utility of the Visible Implant fluorescent Elastomer (VIE) marking technique on a laboratory population of Rio Grande silvery minnow. An initial assessment of recapture ability and rate was also to be performed. A yellow tag (ca. 5-6 mm) was inserted on the left side (above the lateral line and immediately anterior to the dorsal fin) of 4,600 silvery minnow while a green tag was placed (same location) in 7,300 silvery minnow. The two different lots (yellow marked and green marked) were maintained separately and ultimately released separately at two localities in the San Acacia Reach of the Rio Grande on 9 January 2002.