ORCA Heysham-Douglas surveys

Four highly trained volunteers recorded cetacean sightings using line transect distance sampling methods from a ferry crossing the Irish Sea between Heysham, England and Douglas, Isle of Man between July 2011 and September 2016, excluding 2015. Two observers searched a 100 degree area ensuring overlap at g(0) while one observer recorded information on location, vessel speed and weather every 30 minutes or whenever conditions changed while the fourth person rested. Observers rotated every 30 minutes.