Semester

Summer

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Amy Welsh

Committee Co-Chair

Holly Morris

Committee Member

Holly Morris

Committee Member

Laura Gigliotti

Abstract

North American river otters (Lontra canadensis), hereafter, otters, are apex predators in aquatic ecosystems across Appalachia, and thus have important impacts on their ecosystems such as food web regulation, nutrient cycling, and reducing the impacts of invasive species. Otters were extirpated from most of Appalachia, including all of West Virginia, by the mid-1900’s due to habitat destruction and overharvest. The West Virginia Division of Natural Resources (WVDNR) began an otter reintroduction program in 1984 which translocated approximately 250 otters into the state by 1997. This reintroduction program was largely considered successful, and a regulated harvest season was opened in 2011. Despite these successes, challenges to otter conservation and management in West Virginia persist. The WVDNR Wildlife Resources Section is responsible for managing wildlife and fish populations at sustainable levels, and as such, has identified two main challenges facing contemporary otter conservation and management: human-wildlife conflict and a lack of understanding regarding the population genomic impacts of the reintroduction program. This thesis was aimed at addressing both challenges. In chapter 1, I addressed human-otter conflict. Otter recovery has been complicated by concern that they consume stocked trout (Oncorhynchus sp., Salmo sp., and Salvelinus sp.) to an extent that is economically harmful to West Virginians. To address this issue, I conducted a multilocus DNA metabarcoding assessment of otter stomach contents (n=86) collected from licensed trappers and as roadkill from 2020-2023 to determine diet composition of otters across West Virginia. This is the first study to utilize DNA metabarcoding to assess both vertebrate and invertebrate otter diet. I found that the most common diet items were fish in the family Centrarchidae (sunfishes) and invertebrates in the family Cambaridae (crayfish). Trout occurred in only 10% of sampled otter stomachs. No differences in diet composition were observed according to age, sex, or year. These data will be used to assess the extent to which an increase in otter harvest is an appropriate management strategy for otters in West Virginia. In chapter 2, I addressed the lack of understanding regarding the population genomic impacts of the reintroduction program. I amalgamated otter tissue samples (n=395) collected from 2006-2023 from across several U.S. Appalachian states in which otters were reintroduced (Maryland, Ohio, Pennsylvania, Virginia, and West Virginia) as well as from the two primary source states for the reintroductions (Louisiana and North Carolina). I analyzed 13,468 single nucleotide polymorphisms (SNPs) using a double digest restriction-site (ddRAD) method. These results indicated that two genetically defined populations are present across Appalachia (K=2); western Ohio was genetically differentiated from the rest of the study area. Virginia and West Virginia’s populations had lower genome-wide heterozygosity measures than the source states and effective population sizes were low across the study area (Ne < 500). These data will guide conservation decision-makers as to how we can best ensure the long-term persistence of this species. These results are also informative as to Appalachian ecosystem recovery progress.

Download

Included in

Biodiversity Commons

Share

COinS