i.

I studied the effects of vessel activity on the behavior of humpback whales (Megaptera novaeangliae) near Juneau, Alaska, from 6 July to 25 August 2000. I collected behavioral data from a 7 m inboard-outdrive research vessel in Stephens Passage and Lynn Canal, where feeding Central North Pacific humpbacks are the focus of a burgeoning whale watching industry. Utilizing continuous and point behavioral sampling, I recorded locations, identities, and behaviors of 27 humpback whale focal pods for 39.6 observation hours. I also recorded number, type, approach style, length of stay, and proximity ofwhale watching boats within 400 m of each focal pod. I observed 16 pods (1404 total min.; 261 surface intervals) when at least one whale watching boat was present for more than ten minutes, and observed 11 pods (972 total min.; 191 surface intervals) when no whale watching boats were present. I compared whale behavior between the two conditions, whale watching vessels present and whale watching vessels absent. Average whale respiratory activity was almost identical in the two conditions. However, individual whales followed by whale watching boats showed significandy greater variance in time spent at the surface and number of blows per surfacing than did whales not pursued by boats (F=2.87, p<0.05; F=3.14