Population characteristics of humpback whales in Glacier Bay and adjacent waters: 1999

Gabriele, Christine; Doherty, Janet; Lewis, Tania

We photographically identified 104 individual humpback whales (Megaptera novaeangliae), including 9 mother/calf pairs, in Glacier Bay and Icy Strait between June 1 and August 31, 1999. This is the highest number of whales documented in the study area since the monitoring program began in 1985 and it contributes to an increasing trend from 1985 to 1999. An additional mother/calf pair was identified in May, outside of the normal survey period. Twenty-eight whales were resident in Glacier Bay and 26 were resident in Icy Strait for more than 20 days. Four whales that had not been sighted in the study area since they were calves were identified, bringing the 1974-1999 total number of returning offspring to 31. Twelve of the 23 known-age whales in the study area in 1999 were born to just 4 females (#236, #530, #581, #801). Sea surface temperatures were lower in 1999 than in 1998 when the El Nino Southern Oscillation caused a general warming of ocean temperatures. Analysis of a scat sample from a calf in Glacier Bay contained the remains of fish (tentatively identified as juvenile walleye pollock (Theragra chalcogramma) and Pacific herring (Clupea harengus pallasi)) and invertebrates (possibly euphausiids and Crangonid shrimp). Numerous whale/vessel interactions, including two collisions, occurred in and near the study area.