A non-invasive approach examining North American river otter abundance and sociality

An understanding of population demographics is a key component for developing successful wildlife conservation and management plans. However, elusive and secretive carnivores such as river otters can be difficult to trap and observe, making investigations of population number and social structure extremely challenging. Advances in molecular genetics techniques have facilitated the use of non-invasive methods to examine abundance and genetic structure of wild populations when traditional wildlife survey methods may not be appropriate. I applied non-invasive methods to estimate abundance, sociality and kinship of a population of North American river otters (Lontra canadensis) inhabiting the Humboldt Bay area, California, USA. Through microsatellite multi-locus genotyping and closed population mark/recapture modeling, I estimated abundance as 41-51 river otters in the Humboldt Bay region. Coastal river otters associated in family groups, with evidence for the temporary formation of male bachelor groups. There was fine scale population structuring that was most likely a function of social family groups and isolation by distance gene flow. With these results, we can better understand population demographics of coastal-living river otters and thus inform future research and conservation decisions in the Humboldt Bay region.