Plymouth-Santander

A team of up to four trained volunteers including at least one highly experienced observer recorded cetacean sightings using line transect distance sampling methods from a ferry crossing the western English Channel and Bay of Biscay from Plymouth, UK to Santander, Spain. Two observers searched a 100° area from either side of the ship with a 10° overlap on the trackline to satisfy the assumption that all animals on the trackline are detected while one observer recorded data and the other rested.. Effort information including location, vessel speed, course of vessel and environmental conditions (sea state, swell, precipitation and visibility) were recorded every 30 minutes when observers rotated or when conditions changed. Glare was not collected at this point in time but was sometimes noted in the comments so is only recorded for some surveys.