(10-11-09) Each year, thousands of people set sail aboard whale-watch tour boats with hopes of catching an up close glimpse of one of the planet's largest mammals, but the long-term effects of such substantial whale watch exposure had been relatively unknown — until now.

    In a new issue of "Biological Conservation," a peer-reviewed research journal, published that scientists at the Gloucester-based Whale Center of New England suggests that heavy whale watch exposure is not having harmful effects on the calving intervals, or calf survival, of humpback whales in local waters.

    "What we wanted to do was to look at whether whale watching was impacting whales in the long run, not whether it was causing short-term disturbance," said Mason Weinrich, chief scientist at The Whale Center and senior author of the study. He noted that, while whale watching has become one of the busiest tourism industries, it is not heavily regulated.

    Whale watch boats in the Gulf of Maine operate under a voluntary code of conduct, or guidelines, that are officially endorsed by the National Marine Fisheries Service, the federal agency in charge of managing whale populations in U.S. waters. "Since we have a long-term database on individual whales," Weinrich said, "we thought we could examine whether whales that were watched more often had a compromised reproductive success over time."

    The Whale Center, based at Harbor Loop, has been studying humpback whales, using both whale watch boats and research boats, since 1979. Each humpback whale can be identified using natural markings on both the underside of their tail flukes and their dorsal fin. Using three decades worth of data collected each year from naturalists aboard whale watch boats out of Gloucester and Boston, scientists could assess how often each whale was "watched."

    "Obviously, some whales had lots of exposure to boats, while others had relatively little, giving us a good range of whales to examine," Weinrich said. "We then compared this with the frequency that those whales had calves, and what percentage of those calves survived to at least two years after weaning."

Naturalists and data collectors from The Whale Center regularly work with Capt. Bill and Sons Whale Watch and Seven Seas Whale Watch in Gloucester, as well as Boston Harbour Cruises. However, Weinrich emphasized that the data analysis was not biased "in any way" and that The Whale Center is "independent and not tied financially to any whale watch companies."

800 WHALES AT THE STUDY DATABASE

    The study database contained almost 300 reproductive females and more than 500 calves. Their behavior was observed in the southern Gulf of Maine, primarily around Stellwagen Bank and Jeffreys Ledge off Gloucester and waters southwest of Gloucester Harbor between April and November from 1980 to 2006. Both areas are submerged glacial deposits that, combined with local currents, create "substantial upwelling and nutrient productivity," Weinrich wrote in his report.

    Results of the comparison showed no negative effects of whale watch exposure on any of the parameters that were examined. In fact, those females more heavily exposed to whale watching within a year were found to be more likely to return with calves, and those calves most heavily watched were most likely to survive.

    "This doesn't mean whale watching is good for whales," noted Weinrich, "but it does suggest it is not having negative effects. It really shows how important a healthy environment in the Stellwagen Bank National Marine Sanctuary is for whales, and how that seems to supersede any long term effects that boats may have."

    The Whale Center researchers caution that their findings don't necessarily mean that whale watching should continue unsupervised. "There are a number of caveats to our conclusions," Weinrich notes, "and short-term disturbance of an endangered species, if it is happening, is both illegal and a bad practice. Managers need to decide what they want to manage for, short-term or long-term effects. But it is reassuring to note that we can't find life history impacts on the whales in New England care so much about”.

    "Despite the 'long-term' nature of this study, we only examined the potential impacts of whale watching on humpback whales over a fraction of their lives," he added. Humpbacks are thought to live for 50 or more years and this study at best addresses the effects for approximately half their lives. Weinrich said: "It is possible that long-term exposure to whale watching, and to other vessel traffic, may eventually impact individuals through causing hearing damage or chronic stress, leading to an eventual decrease in fitness."

    However, a 1999 study of the acoustic interaction of humpback whales and whale watching boats off the coast of Hawaii published in Marine Environmental Research concluded it was "unlikely that the levels of sounds produced by the boats in the study would have any grave effects on the auditory system of humpback whales."