Distribution and Relative Abundance of Killer Whale in Irish EEZ 2005-2011

Killer whales are the largest dolphin species, with adults reaching up to 9.5 m in length.The blow is low and bushy with a sharp sound, audible from a distance. The head is rounded with an indistinct blunt beak. The triangular dorsal fin, located half-way along the back, is the largest of any cetacean species and reaches 1.8 m in height in males.The dorsal fin on females and juveniles is falcate and more dolphin-like. Body colour is jet-black above and on the flanks. They have white undersides with a white patch above and slightly behind the eye and a white patch stretching from the underside onto the flanks. A lighter coloured saddle patch varies in colour from white to grey to brownish. Identification at sea is easy if the group contains an adult male, which they almost always do, as there is no mistaking the male dorsal fin. Even females and sub-adults have a noticeably larger dorsal fin than other species. The striking body colouration is also diagnostic. The data collected includes observations, relative abundance, search for and range of Killer Whale (Orcinus orca) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.