the harbour porpoise is found in cool temperate to sub-polar waters in the northern hemisphere. There are an estimated 700,000 harbour porpoises globally, therefore the species is not currently a major conservation concern.Porpoises are difficult to approach and follow, generally avoiding boats and other human activity. Though fast swimmers, they are not acrobatic, rarely breaching or leaping. They make brief dives, usually lasting for less than five minutes. They will often lie motionless at the surface on calm days, either resting or scanning the water below (Watson and Gaskin, 1983). Dive depths in excess of 200 metres have been recorded (Westgate et al, 1995).Hunting and exploitation by humans, exposure to environmental contaminants and incidental capture in fishing nets are the main threats to the harbour porpoise (Jefferson et al, 2008).The Natural History Museum, London, is part of a government-funded collaborative UK research group gathering data on strandings. These data help inform conservation policy makers at both UK and EU level (NHM strandings website, UKCSIP website). They are the most frequently stranded of all cetacean species in UK waters.