Identifiable humpback whales were sighted in Glacier Bay each year, 1976-1977, for a six to twelve week period. In 1978, all but three whales departed the Bay after 16 days. In the summers of 1976-1978 two influxes of whales occurred ([Table 2]). The Juraszs' define an influx of whales as those whales that enter and remain in the Bay for a minimum of three weeks. The second influx arrived 7-14 days after extreme low tides occurred in late June-early July and presumably moved into the Bay on flood tides. In 1979, a single influx comprised of 3 whales entered the Bay. The age composition of identified whales using Glacier Bay was categorized by the Juraszs' for 1976-1978 ([Table 3]).
During the period spent in the Bay, humpback whales have been observed to feed on capelin, euphausiids (Euphausia pacifica), and pandalid shrimp (Pandulus borealis). There appear to be three generalized feeding relationships: 1) early-season feeding on shrimp in the upper Bay; 2) mid-season feeding by concentrations of whales on capelin in the lower Bay; and 3) late-season feeding (around August 5) by concentrations of whales on euphausiids in mid-Bay.
Behaviorally, humpback whales appear to lunge up through concentrated schools of prey during mid-season and use "bubble-netting" as a means of concentrating less dense and/or numerically fewer prey earlier and later in the season. In other areas of southeast Alaska, humpbacks are reported to also feed on herring (Clupea harengus pallasi), shrimp, and possibly other small schooling (swarming) prey. The Juraszs' believe that humpbacks establish feeding territories in the Bay, and have described eight "stress behaviors" associated with violations of those territories ([Table 4]). The data collected by the Juraszs are extensive (including human use of Glacier Bay) but have not yet been completely analyzed.
[3] This summary is based on information provided at the meeting by Charles and Virginia Jurasz.
Human Use of Glacier Bay[4]
John Muir popularized Glacier Bay, leading to tourist activity into the early 1900's, when loose ice resulting from earthquake activity prevented cruise vessels from operating within the Bay. Glacier Bay was designated a National Monument February 26, 1925, the area being added to April 18, 1939.
Vessel and tourist numbers remained low until the late 1960's-early 1970's. Close to 100 percent of the visitors to the Bay use vessels, either entering the Bay aboard them or making use of them to tour the Bay after arriving by aircraft. The Juraszs' developed a classification scheme for vessels and aircraft based upon activities of the craft in the Bay, their size, hull design, and engine characteristics ([Table 5]).