Genetic Analysis of River Otters in Possession Sound

• Main Author: Sams, Elayna
• Format: Text
• Language: English
• Published: Western CEDAR 2014
• Subjects: Terrestrial and Aquatic Ecology; American River; Orca; Lontra
• Online Access: https://cedar.wwu.edu/ssec/2014ssec/Day2/63

The North American river otter (Lontra canadensis) inhabits freshwater rivers, lakes and marine coasts across much of North America, yet population estimates of this species are often difficult to obtain or nonexistent. It is challenging to assess populations of L. canadensis by means such as live-capture; however, non-invasive fecal sampling has emerged as a viable way to assess many aspects of river otter ecology including diet and genetics. L. canadensis regularly defecates and scent marks at specific locations, known as latrine sites. Fecal samples collected from latrine sites can be used in DNA analysis to distinguish unique individuals and assess genetic diversity in a population (Guertin 2002). Within Possession Sound, located in the Northeast Whidbey Basin of Puget Sound, minimal research on the abundance and diversity of L. canadensis has been conducted. In fall of 2012, students at the Ocean Research College Academy (ORCA), an early college program at Everett Community College, became the first to study the species in this area. As of fall 2013, two latrine sites of L. canadensis in Possession Sound have been monitored using motion-sensing camera traps. Weekly checks for fresh scat and anal jellies are performed, with 129 samples collected thus far. Scat samples are utilized in DNA extraction and DNA amplification through PCR. Diet is also assessed by identifying prey remains present in feces. DNA analysis results will provide valuable information about the previously unknown number of individual otters, which are indistinguishable from each other on camera footage. It is expected that DNA analysis will identify a relatively small number of individuals, as the maximum number of individuals simultaneously captured on video footage is seven otters. Due to the seasonally constant and geographically limited territory of L. canadensis, we expect there to be a small population size, and therefore some amount of genetic inter-relatedness in the individuals identified through DNA analysis.