Master of Science, The Ohio State University, 2021, Environment and Natural Resources
The North American river otter (Lontra canadensis) is a vitally important species, both biologically as an apex predator in riverine ecosystems, and economically as a furbearer species. River otters were once present throughout much of North America but were extirpated throughout much of the central United States by the 1970s due to excessive harvest, habitat loss, and other factors. Several reintroductions occurred throughout the 1980s and 1990s including an effort in Ohio between 1986-1993. The reintroduction effort in Ohio was considered successful enough that legal harvest was reimplemented in 2005. Since 2005 Ohio Division of Wildlife data has suggested that harvest is largely successful and sustainable, but little attention is currently being paid to population demographics and spatiotemporal variation of the populations in the state, especially as they relate to survival probability and harvest vulnerability.
Additionally, the diet of river otters in Ohio and how it varies with age group, sex, and region are not well understood. Several studies have examined river otter diet in other locations using scat analysis, and the diet of other species of otters have also been studied with stable isotope analysis. Previous research has indicated that river otters eat smaller fish in shallower waters or larger, less mobile, bottom-feeding fish, in addition to some invertebrates that help supplement their diet.
This study documented the current demographics of the river otter population in Ohio; modeled population trends, survival probability, harvest vulnerability, and recruitment trends for the river otter population in Ohio, determined the contribution of several prey items or prey item groups to river otter diet via stable isotope analysis, and determined how the contributions of these prey items or prey item groups varied with age group sex and location.
Population demographics, specifically the larger share of older individuals and older reproductive females, (open full item for complete abstract)
Committee: Stanley Gehrt (Advisor); Hance Ellington (Committee Member); Jeremy Bruskotter (Committee Member); Mažeika Sullivan (Committee Member)
Subjects: Ecology; Environmental Science