Injuring The Whales They Love To Watch: Tourist Boats Hitting More Humpbacks In Hawaii
Whale-watchers who get an up-close view may be fascinated by the marine mammals, but tourist boats are the apparent cause of an increasing number of collisions with humpback whales in Hawaiian waters.
The number of whales struck by small- to medium-sized vessels in the seas around the Hawaiian islands has steadily increased over the years, according to a report by Marc O. Lammers, an assistant researcher in marine bioacoustics and Cetacean behavior at the University of Hawaii at Monoa. The report, with co-authors A.A. Pack, E.G. Lyman, and L. Espiritu, is published in the 2013 issue of the Journal of Cetacean Research and Management.
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"The majority of incidents occurred in the waters in the Maui Nui region, a relatively shallow area, at less than 200 meters in depth, with one of the densest aggregations of humpback whales in the Hawaiian islands," according to the report. "This is also an area of high vessel concentration, especially during whale-watching months. The majority of incidences over the past five years in which the vessel type was specified involved commercial whale-watching vessels."
Most of the boats involved in the collisions were less than 21.2 meters, or about 69 feet, in length — generally the size of whale-watching vessels, Science magazine reported.
"The rate of collisions increased significantly over the final 12 breeding seasons of the study and was greater than predicted by the estimated annual increase in the whale population, suggesting that the rising number of reported collisions cannot be explained solely by the annual increase in whale abundance," according to the study. The report did not have specific numbers of whale injuries or deaths resulting from the vessel strikes.
The vessels are required to remain at least 100 yards away from the humpbacks under federal regulations, according to Science. Even though boats may be staying at the required distance when observing the whales, the majority of collisions occurred when the boats were likely under way, traveling at 10 to 19 knots, Science reported. That speed made it difficult, or impossible, to avoid collisions with the whales the tourists came out to watch.
From December to April, about 10,000 humpback whales congregate in waters around the Hawaiian islands. More than 63 percent of the boat strikes involved calves and other juvenile whales, suggesting a greater susceptibility toward collisions among younger animals, most likely because they spend more time at the surface to breathe than the adult humpbacks, according to Science.
"There is mounting evidence that collisions between whales and vessels are increasing globally," according to the study. "Encounters at sea are becoming more frequent, sometimes with disastrous consequences for the whales, humans, or both. This is notably true in areas where both human and whale concentrations are high, such as coastal urban areas in the proximity of whale feeding or breeding grounds. One such location is the Hawaiian islands where humpback whales (Megaptera novaeangliae) congregate seasonally between December and April and where in excess of eight million people reside or visit annually."
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