Lucas, ZN & LJ Natanson. 2010. Two shark species involved in predation on seals at Sable Island, Nova Scotia, Canada. Proceedings of the Nova Scotian Institute of Science 45(2): 64-88.
Summary (ZL): Between 1993 and 2001, 4906 seal corpses bearing wounds likely inflicted by sharks were examined on Sable Island. Five species of seal were involved: grey Halichoerus grypus, harp Pagophilus groenlandica, harbour Phoca vitulina, hooded Cystophora cristata, and ringed Phoca hispida seals. Flesh wounds on seal corpses indicated that two or more shark species prey on seals in waters around Sable Island. Wounds were categorized as either “slash” or “corkscrew”. Wound patterns, tooth fragments, and marks on bones indicated that white sharks Carcharodon carcharias likely inflicted the slash wounds. However, >95% of seal corpses bore the corkscrew wounds and these wounds could not be attributed to shark species identified in attacks on pinnipeds in other regions. Also, the corkscrew wounds were previously unreported in the literature. Circumstantial evidence indicates that attacks by Greenland sharks Somniosus microcephalus were responsible for the clean-edged encircling corkscrew wounds seen on seal corpses washed ashore on Sable Island.