Relative frequencies of seal wounds: A case study on Mount Desert Rock, Maine

Clark, Kaitlyn; DenDanto, Dan; Petersen, Christopher

From the abstract: "Seal populations in the Gulf of Maine have been gradually increasing in recent years. This has lead to both grey seals (Halichoerus grypus) and harbor seals (Phoca vitulina) hauling out in large numbers on Mount Desert Rock (MDR), a small island about 45 km off the coast of Mount Desert Island, ME. In an area of high fishing activity, the population dynamics of H. grypus and P. vitulina are particularly interesting in relation to the potential for interactions with boats and fishing gear. These interactions sometimes result in wounds, and the seals that haul out on MDR often display wounds severe enough to be viewed with binoculars from the light tower on the island. This summer, I conducted research on MDR that focused on the relative frequencies of different wounds in the seal populations as well as the differences in behavior between wounded and unwounded individuals. The study results show some differences in the percentage of wounds in each species and at different tidal heights. Of particular interest relating to human involvement, 0.50% of the P. vitulina population and 2.59% of the H. grypus population hauled out at low tide were entangled with line around the neck. These percentages place both populations within the range of entanglement rates in other pinniped populations around the world. These data could provide baseline information for monitoring the health of Gulf of Maine seal populations in the future."