River otters were extirpated in West Virginia in the mid-1900’s due to watershed pollution, habitat destruction, and unregulated harvesting. Because river otters are an apex predator in aquatic habitats in West Virginia, they help regulate ecosystem function. The WVDNR established a river otter reintroduction program in the 1980’s and 90’s in an effort to restore a native species to West Virginia. For the program, the WVDNR translocated otters from Louisiana, Maryland, North Carolina, and South Carolina to various rivers across West Virginia. The goal of this project was to release enough individuals to secure long-term population stability of river otters across the state. In 2011, the WV otter population was considered recovered enough to establish a trapping season from the first weekend in November to the end of February.
To study the impact of the otter reintroduction on long-term population stability, we examined genetic patterns in otters from West Virginia and surrounding states. We also examined the genetic patterns of otters in North Carolina and Louisiana, which is where otters were sourced for the reintroduction program. Our genetic analysis provides evidence that there are two genetic populations of otters across the study region: otters in northwestern Ohio are genetically distinct from otters elsewhere in the study area (Figure 1). This led us to conclude that otters in western Ohio are not descendants from a reintroduction program, but naturally recolonized northwestern Ohio from Michigan (where otters were never extirpated). The otters elsewhere in the study area appear to be descendants of the reintroduction program because of their genetic similarities to otters in Louisiana and North Carolina. Overall, this analysis provides evidence that the West Virginia reintroduction program was successful in restoring otter populations.
Management Implications: This study found that the otter reintroduction program in West Virginia was successful in restoring otter populations to the state. To ensure long-term persistence of otters across Appalachia, this study recommends that managers focus on landscape connectivity across Ohio. Increased connectivity from the distinct western Ohio population could increase genetic diversity for otters across Appalachia, which could increase their potential to adapt to future habitat changes or diseases.
Figure 1. Map showing where otter DNA samples for this study were collected, with each dot representing an individual otter. The red circle roughly represents the northwestern Ohio area where otters were found to be genetically different from the rest of the study area.