Rio Grande Silvery Minnow Augmentation in the Middle Rio Grande, New Mexico Annual Report 2022


Date: 2023/02/21

Author(s): Archdeacon T.P.

Publication: Prepared by U.S. Fish and Wildlife Service, New Mexico Fish and Wildlife Conservation Office. Prepared for U.S. Bureau of Reclamation, 36 p.


  • This report covers New Mexico Fish and Wildlife Conservation Office (NMFWCO) RioGrande Silvery Minnow (RGSM) augmentation activities for the 2022 cohort.
  • Spring runoff in early 2022 was moderately low, resulting in a request of 230,000 hatchery-reared age-0 fish to supplement the wild 2021 cohort and an additional 10,000 RGSM for a movement study.
  • The visible implant elastomer (VIE) tags used for identifying RGSM released in 2022 was red left dorsal for all facilities.
  • Based on September 2022 population monitoring, the Middle Rio Grande valley had <1.0 RGSM per 100m2 and >50% occupied sites in all reaches, leading to a final request of 269,000 RGSM. However, due to poor reproduction, growth, and survival of hatchery fish, this production request was not met. An additional 10,000 were held back as emergency broodstock for future use if required, reducing total numbers available to release further.
  • 126,504 hatchery-reared age-0 Rio Grande Silvery Minnow were released in November and December 2022. All were given a red left VIE tag prior to release.
  • 2,993 PIT tagged fish were released in March 2022.
  • 454 VIE-marked fish were recaptured between January and December 2022, with 7 from the 2020 cohort, 1 former broodstock, 3 PIT-tagged fish, and the remaining 443 from the 2021 cohort. The majority of recaptures (N = 366) were during fish rescue activities, including all fish from the 2020 cohort.
  • A pilot mark-recapture study was initiated to determine the feasibility of robust-design mark recapture to estimate monthly survival, movement, and capture efficiency of Rio Grande Silvery Minnow.

Related Information

Species: Rio Grande Silvery Minnow

Organization: U.S. Bureau of Reclamation , U.S. Fish and Wildlife Service