Within this context, our response addresses those National Park Service (NPS) actions controlling human activity that may, in turn, affect the humpback whales within Glacier Bay.
Biological Background
In the North Pacific, the summer range of the humpback whale encompasses the area from Bering Strait south to the Subarctic Boundary (ca. 40° N lat) and extends in the east to about Point Conception, California, and the Sanriku Coast of Honshu Island in the west. Humpbacks range into shallow coastal waters more frequently than do most other balaenopterids and regularly occur in sheltered inside waters of Prince William Sound and the Alexander Archipelago of southeastern Alaska.
The wintering grounds of humpbacks in the North Pacific are centered in three areas: (1) the coast and adjacent islands of west-central Mexico; (2) the main Hawaiian Islands; and (3) the Bonin, Ryukyu, and Mariana Islands in the western North Pacific. Some humpbacks that summer in southeastern Alaska are known to migrate to both the Mexican and Hawaiian wintering grounds, although others are found in southeastern Alaska during all months of the year.
Prior to the rise of modern whaling in the late 1800's, the world population of humpback whales exceeded 100,000, mostly in the Southern Hemisphere. The North Pacific population probably numbered roughly 15,000 at the turn of the century.
Whaling in southeastern Alaska began in 1907 with the establishment of two land stations. The number of humpback whales at the start of this earliest exploitation is unknown. Consistent catch records are available only for 1912-1922, during which time 185 humpbacks were taken, with a peak catch of 39 in 1916.
Since 1922, no whaling has been conducted in the territorial waters of southeastern Alaska. However, the humpback whales of the inside waters were exposed to additional exploitation as they migrated across the high seas or through the coastal territorial waters of British Columbia, Washington, California, and Baja California.
By 1966, when humpbacks were accorded complete legal protection by the International Whaling Commission, the world population of the species had been reduced to about 5,000. The North Pacific population now numbers about 1,000, of which 600 or 700 winter in the Hawaiian Islands, and 200 or 300 winter in Mexico. Only a few humpbacks have been sighted on the western North Pacific wintering grounds in recent years. Since 1966 no trends in abundance have been observed either for the North Pacific population as a whole or on any of its wintering or summering grounds, including southeastern Alaska.
Based upon aerial and vessel surveys, the population that spends the summer in the inside waters of southeastern Alaska numbers at least 70. Photoidentification studies now underway tentatively reveal that the population may exceed 100. Although it ranges throughout the area from Sumner Strait northward, its main concentration areas are Frederick Sound-Stephens Passage, where a minimum of 40 whales occurs, and Glacier Bay, where 20-25 whales occur. Humpback whales congregate in these areas to feed upon the summer blooms of euphausiids, herring, and capelin. Some whales arrive in June and stay on through early September, although as mentioned earlier, other animals appear to remain through the winter months.
When humpback whales historically began occupying Glacier Bay is unknown, but they have occurred there every summer over the past seven years of investigation. Photoidentification techniques indicate that certain individuals repeatedly return to feed there.