Migration and local movement of humpback whales (Megaptera novaeangliae) through Hawaiian waters

Abstract

Aerial surveys of the population of humpback whales assembled in Hawaiian waters during the 1977, 1978, and 1979 winter seasons were carried out on a weekly to biweekly basis during the major period of residency, from mid-January through mid-April. A progressively later date for peak numbers was found over the 3 years. These annual changes in migratory timing were consistent with earlier data for humpback whales in the western North Pacific but differed from the constant migratory timing reported for South Pacific humpback whales. Regional data showed that each year the earliest peak influx was at the island of Hawaii (Big Island), with regions to the northwest showing progressively later dates for peak residency. Kauai-Niihau, the island group furthest to the northwest, but separated from other islands by extensive deep water channels, seemed to follow an independent trend. Photographic reidentification of seven whales that moved from the Big Island or from the Maui area to regions to the northwest provided supporting evidence for the southeast to northwest movement pattern indicated by aircraft data. This pattern suggested that some whales use the prevailing clockwise surface currents in the upper North Pacific to aid their migration between Alaskan feeding grounds and Hawaii.