Lucas, Z, P-Y Daoust, C Conboy & M Brimacombe. 2003. Health status of harps seals (Phoca groenlandica) and hooded seals (Cystophora cristata) on Sable Island, Nova Scotia, concurrent with their expanding range. Journal of Wildlife Diseases 39(1): 16-28.
Abstract: “Beach surveys for harp (Phoca groenlandica) and hooded (Cystophora cristata) seals documented a dramatic increase in their numbers on Sable Island in mid 1990s. In the 1980s, no more than five animals of both species were observed on this island each year, however, during late 1994 to 1998, 1,191 harp and 870 hooded seals, mostly young animals, were recorded. Although some of these seals had been killed by sharks, most (roughly 75%) were found alive or as intact carcasses on the beach, and some of the live seals were later found dead. Emaciation/starvation was considered the primary cause of death in seals that were not obviously killed by sharks. Factors that may have compounded this poor body condition included gastric impaction with abnormal ingesta, hemorrhagic diathesis possibly induced by parasitic migration and secondary vasculitis, and stomatitis (in hooded seals only). Some harp and hooded seals expanding their range in recent years may be unable to feed successfully, although the reasons for this are unclear.”