Hydroacoustic Surveys and Identification of Humpback Whale Forage in Glacier Bay, Stephens Passage, and Frederick Sound, Southeastern Alaska, Summer 1983

摘要

Prey of humpback whales, Megaptera novaeangliae, were identified and hydroacoustically surveyed in the Glacier Bay-Icy Strait and Stephens Passage-Frederick Sound areas of southeastern Alaska in August and September 1983. Midwater trawls were used to identify the prey, which were either small fish or euphausiids. The prey were hydroacoustically quantified at whale foraging sites and indexed along the same transects surveyed during the Whale Prey Study in 1981 and 1982. The spatial distribution of fish and micronekton along Glacier Bay transects in 1983 was similar to the distribution observed in 1982. A seasonal increase of backscattering density from early August to mid-September was also attributed to higher euphausiid densities near Geikie Inlet.