HUMPBACK WHALES (MEGAPTERA-NOVAEANGLIAE) IN HERVEY BAY, QUEENSLAND - BEHAVIOR AND RESPONSES TO WHALE-WATCHING VESSELS

The effects of the presence of vessels on the behaviour of humpback wh ales (Megaptera novaeangliae) was studied in Hervey Bay, Queensland, w here southward-migrating whales are the focus of a commercial whale-wa tching industry. The behaviour of whales was observed from a small yac ht under sail. Rates of occurrence of units of behaviour for entire po ds were obtained from continuous sampling of pods. Pods without calves showed lower rates of behaviour generally when vessels were within 30 0 m of them. Pods both with and without calves:were more likely to div e rather than slip under when vessels were within 300 m. Hybrid multid imensional scaling of rates of behaviours of pods indicated difference s between suites of behaviours exhibited by pods when vessels were wit hin 300 m of them and when they were not. Classification of the patter ns of occurrence of behaviours demonstrated that for pods both with an d without calves, different units of behaviour tended to occur togethe r when vessels were within 300 m and when they were not. Whale watchin g offers a nonlethal commercial use of whales, but in Hervey Bay, whal e watching affects the behaviour of whales, which, although migrating, can be involved in breeding ground activities. Whether the short-term behavioural changes described here are accompanied by longer term avo idance of Hervey Bay by humpback whales as they migrate south remains to be determined.