Seasonal occurrence and annual return of humpback whales, Megaptera novaeangliae, in the southern Gulf of Maine

Abstract

A study of 518 individually identified humpback whales (Megaptera novaeangliae) in the southern Gulf of Maine between 1979 and 1988 showed high rates of both within-season occurrence and annual return. On average, 77.3% of whales were resighted on more than 1 day during the year (maximum 83 days), with occupancies ranging from 1 to 324 days (mean 88.1 days). The mean rate of return of individuals in consecutive years was 73.2% (range 59.1–87.4%), and the majority of whales were still being resighted up to 10 years later. Only 13 humpbacks were recorded during 50 midwinter surveys. Variation in the occurrence of individuals appears to be related to variability in the abundance of prey and perhaps to regional preferences.