Genetic Effects of Hatchery Propagation and Rearing in the Endangered Rio Grande Silvery Minnow, Hybognathus amarus

The Rio Grande silvery minnow, Hybognathus amarus, is a federally endangered cyprinid now confined to the middle Rio Grande, New Mexico, in a fraction of its former range. The precipitous decline of the remaining wild population and lack of recruitment in the summer of 2000 prompted collection and placement of eggs and wild fish in propagation facilities. The aim of this study was to assess the genetic effects of hatchery propagation in the Rio Grande silvery minnow using 10 microsatellite loci and partial mitochondrial ND4 sequences. Three hatchery stocks (2001, 2002, and 2003) and the wild source population (collected in 2001–2002) were considered. Principal findings were; (i) captively spawned and reared Rio Grande silvery minnow had depleted levels of allelic diversity but similar levels of heterozygosity to the wild population, and (ii) fish raised from wild-caught eggs maintained similar levels of allelic diversity but had higher inbreeding coefficients than the wild source stock. With the repatriation of over 500,000 Rio Grande silvery minnow to the Rio Grande, the genetic effects of propagation are likely to impact the remaining wild population, especially as numbers in the wild continue to decline.

Keywords:

• captive propagation
• microsatellite loci
• mitrochondrial DNA ND4
• allelic diversity
• heterozygosity

Acknowledgments

Our sincere thanks are extended to S. P. Platania (SPP), R. K. Dudley, W. H. Brandenburg, A. M. Snyder, M. A. Farrington, C. S. Altenbach, M. D. Porter, J. E. Brooks, D. L. Propst, M. Ulibarri, the Albuquerque Fishery Resources Office of the U.S. Fish and Wildlife Service, and the Museum of Southwestern Biology for technical and logistic support throughout the project. G. Rosenburg and the staff of the UNM Molecular Biology Core Facility provided vital technical support. Funding was provided by New Mexico Department of Game and Fish, the U.S. Forest Service, the U.S. Bureau of Reclamation, the U.S. Fish and Wildlife Service, and the National Science Foundation. The manuscript benefited from comments by G. Moyer and two anonymous reviewers. Rio Grande silvery minnow were collected under Federal Fish and Wildlife Permits TE001623-0 (SPP) and TE038055-0 (TFT) and the New Mexico Department of Game and Fish Scientific Collecting Permits 1896 (SPP) and 3015 (TFT).