In a worst case analysis, Glacier Bay is a feeding ground, and its long-term abandonment would not be conducive to the conservation of the humpback whale. Up to 20 or 25 individual whales would relocate to other areas, increasing competition for food there. In such case a greater expenditure of energy might be required to obtain the same quantities of food than would be required in Glacier Bay. An increased energy expenditure would tend to decrease the likelihood of humpbacks successfully increasing their numbers, since growth and the onset of sexual maturity would be delayed.
Our present interpretation of the available data is that uncontrolled increase of vessel traffic, particularly of erratically traveling charter/pleasure craft, probably has altered the behavior of humpback whales in Glacier Bay and thus may be implicated in their departure from the Bay the past two years. Our conclusion, then, is that continued increase in the amount of vessel traffic, particularly charter/pleasure craft, in Glacier Bay is likely to jeopardize the continued existence of the humpback whale population frequenting Southeast Alaska. The alteration in the distribution of the whales in Southeast Alaska can be expected to appreciably reduce the likelihood of the recovery of the North Pacific humpback population, especially when viewed as an incremental aggravation of the problem of humpback/human interaction in general.
Until research reveals the need for more specific action, if any, we offer the following as reasonable and prudent alternatives that the NPS should institute in Glacier Bay to avoid jeopardizing the continued existence of the North Pacific population of humpback whales:
We recommend that total vessel use of the Bay be restricted to 1976 levels, at the very least, since that year preceeded the high point of visitor use in Glacier Bay during 1977. Commercial use of the Bay is predicated on a permit system that should offer good control and accountability of the tour industry. The routing of large vessels is relatively easy to regulate. Recreational craft present the greater challenge to management control. The continuing increase in the amount of recreational traffic in the Bay lends considerable urgency to establishing effective controls.