Using Genetics To Study Otter Connectivity And Population Size In Northwestern Montana

Scientific Disciplines
Biological Sciences - Terrestrial
Biological Sciences - Aquatic
University of Montana
Volume 17, No. 1-4

Using genetics to study otter connectivity and population 
Size in northwestern montana
Darin Newton,* Wildlife Biology Program, University of Montana, Missoula, Montana 59212,
Kerry Foresman, Wildlife Biology Program, University of Montana, , Missoula, Montana 59212,
River otters (Lontra canadensis) have begun to recover in the Upper Clark Fork River 
(UCFR) after decades of mining and smelting activity severely impacted the population.  An 
initial project in 2009 showed otters occur throughout the UCFR but at seemingly lower 
densities than other rivers in Montana. We are working to estimate otter population size in 
the UCFR and determine connectivity between other geographically close rivers. We are 
using 11 microsatellite loci amplified from tissue samples collected from trapped otters to 
look at connectivity between 5 rivers: the Bitterroot River, Blackfoot River, Clearwater 
River, UCFR, and Lower Clark Fork River. We are using heterozygosity and Fst values to 
indicate population substructuring as well as using principle component analysis to visualize 
any differentiation. Additionally, we are using hair collected from hair snares to genetically 
estimate population size in the UCFR. Initial results from tissues indicate that otters in the 
5 rivers are highly connected, and no one population is more connected to the UCFR than 
another. These results are based on a small samples size; additional samples currently being 
analyzed will enhance our ability to interpret this situation. Additional samples will be 
collected in 2011 to strengthen the population estimate. This is one of a few projects, and the 
first in Montana, to use genetics to look at population substructuring in otters.