Cooperative Fish and Wildlife Research Units Program: Wyoming
Education, Research and Technical Assistance for Managing Our Natural Resources

Evan Booher and Annika Walters. Identifying translocation sites for a climate relict population of Finescale Dace (Chrosomus neogaeus). Transactions of the American Fisheries Society


Native freshwater fishes are increasingly imperiled by biological invasions, habitat loss, and rapid alteration of hydroclimatic regimes. Translocation is a management strategy which addresses these threats by seeking to establish additional extant populations for species of conservation concern. Finescale Dace Chrosomus neogaeus populations in the Great Plains may benefit from translocation as they exhibit a climate relict natural history that has led to a disjunct distribution and minimal dispersal opportunities. We assessed the translocation suitability of sites for Finescale Dace in the Belle Fourche Basin using a multi-model approach. We used multivariate analyses (MVA) to evaluate dissimilarity in fish occurrence and habitat between sites with and without Finescale Dace in contemporary surveys from 2018 – 2019 (n = 68). We further evaluated the intrinsic potential (IP) for sites to support Finescale Dace using predicted probability of occurrence values from species distribution models (SDM) fit with basin-wide fish occurrence surveys from 2008 – 2019 (n = 124) and spatially continuous environmental variables including forecasted stream temperature scenarios. Sites with Finescale Dace tended to occur close to lentic waterbodies, contain emergent vegetation cover, and did not exhibit large overlap in species-space with either native or nonnative species. Predicted probability of Finescale Dace occurrence exhibited non-linear relationships to mean August stream temperature, channel slope, and baseflow index. The amount of suitable habitat (i.e., high IP scores) declined with forecasted stream warming scenarios. We ranked potential translocation sites based on: distance measures from occupied sites in the 1) habitat MVA, 2) fish community MVA, and 3) extracted IP scores for current and future warming scenarios. Our highest ranked translocation sites provide a basis for management actions aimed at safeguarding an at-risk climate relict fish population into the future and our approach may be transferable to other wild animal populations with restricted distributions.