ORCA Aberdeen-Lerwick surveys 2023

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 northern North Sea between Aberdeen, mainland Scotland and Lerwick, Shetland. Two observers searched a 100 degree area from either side of the ship with a 10 degree 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, glare and visibility) were recorded every 30 minutes when observers rotated or when conditions changed. Glare was originally recorded as the position of glare relative to the ship.