Abstract

The seasonal distribution of harbour porpoises in US Atlantic waters is explored by examining aerial sightings made by the CeTAP survey between 1978 and 1988. Sightings rates were very low in winter months, with no clear pattern of distribution. The months of April and May were characterised by an aggregation of animals on or around George’s Bank, while in June, a period of peak conception, sightings were more dispersed throughout the Gulf of Maine. These sightings and the annual aggregation in the summer months around the entrance to the Bay of Fundy are discussed in relation to population identity, while a possible shift in the spring-time distribution from the late 1970s to the late 1980s and early 1990s is also noted by comparing CeTAP data with NMFS aerial survey and bycatch-rate data.