Whale watching impact on humpback whales

Weinrich M., Corbelli C. 2009. Does whale watching in Southern New England impact humpback whale (Megaptera novaeangliae) calf production or calf survival? Biological Conservation 142: 2931–2940.

ABSTRACT
There is growing concern about the effects of wildlife tourism on biologically important parameters in target species and/or populations. We tested whether whale watch vessel exposure affected either the calving rates or calf survival to age 2 in humpback whales (Megaptera novaeangliae) on their feeding grounds off of southern New England, where individually identified whales have been studied intensively for decades and whale watch pressure is intense. Whale watch exposure did not correlate with either the calving rate (# of calves/# of years sighted) or calf production and survival of individual females, although a breakpoint analysis showed a slight negative trend up to 1649 min (or 20 boat interactions). In some comparisons, whales with more exposure were significantly more likely to produce calves and to have those calves survive. Logistic regressions including exposure and prey variables also failed to show negative effects of exposure in predicting calf productivity or survival. A limited comparison of calves seen only in an alternate habitat without whale watching showed similar return rates to those in the exposed area. Our data include limited suggestions that some animals (i.e., females alive when whale watching started) might be more susceptible to impacts than others. However, we found no direct evidence for negative effects of whale watch exposure, and suggest that short-term disturbance may not necessarily be indicative of more meaningful detrimental effects on either individuals or populations.