WATER REQUIREMENTS FOR ENDANGERED SPECIES - RIO GRANDE SILVERY MINNOW (HYBOGNATHUS AMARUS)

47th ANNUAL NEW MEXICO WATER CONFERENCE

地球科学;生态环境科学

David E. Cowley

Others  :  http://wrri.nmsu.edu/publish/watcon/proc47/cowley.pdf
PID  :  13098

学科分类：环境科学（综合）

来源: CEUR

【 摘 要 】

The biology of many endangered species is poorly known. This is well illustrated by the critically endangered Rio Grande silvery minnow. Clear understanding is lacking of its food habits, cover requirements, where and how it reproduces, river channel features that improve juvenile recruitment, and if the species retains sufficient genetic diversity to continue its evolutionary sojourn. It is well known that the Rio Grande silvery minnow's eggs and larvae can be transported downstream. Downstream transport in one phase of the life history must be offset by upstream passage, otherwise extinction is inevitable.Prior to 1975, the species was sustained in the middle Rio Grande by having an upstream source population in the perennially wetted reach from Algodones to Espa ola and Abiquiu. Recurring dry riverbeds during this time did not have a large negative effect on the Rio Grande silvery minnow because it was often found to be an abundant species in the middle Rio Grande. Closure of Cochiti Dam in 1975 led to the loss of the upstream source population and to greater modification of the river flows. The species currently has a high vulnerability to extinction because it is forced to live in reaches that have often gone dry inthe past. Recovery of the species would be enhanced by (1) restoring the species upstream from Cochiti, (2) removal or re-engineering of Cochiti Dam to provide fish passage, (3) providing upstream passage at downstream diversions in the lower river reaches, and (4) developing naturalized refugial habitats in the lower desiccation-prone reaches. The parsimony here is that the Rio Grande silvery minnow and the valley's farmers coexisted for many years prior to Cochiti Dam without supplemental water for the minnow.