With only 400 to 500 in existence, endangered North American right whales must congregate in the Roseway Basin off the coast of Nova Scotia to feed and find mates, Susan Parks says. (Credit: Georgia Wildlife Resources Division/Flickr)

acoustics

Endangered whales are breeding in a busy shipping lane

Using remote acoustic monitoring, researchers have identified the Roseway Basin, a heavily traveled shipping lane off the coast of Nova Scotia, as a breeding ground for endangered North Atlantic right whales.

“Our results support the hypothesis that the North Atlantic right whale’s breeding season occurs mostly from August to November and that this basin is a widely used habitat area,” says Susan Parks, assistant professor of biology at Syracuse University.

More than 30 percent of all right whales use Roseway Basin, part of a larger geological formation called the Scotian Shelf, throughout the year. With only 400 to 500 in existence, these whales must congregate in the basin to feed and find mates, Parks says.

Already, the US and Canadian governments have taken steps to redirect shipping traffic, in response to several fatal collisions with right whales.

“Part of the answer lies in a loud ‘gunshot’ sound, made by the male whale,” says Leanna Matthews, a member of Parks’ lab and lead author of a new study published in PLOS ONE.

“We’re not exactly sure what the gunshot is, but we think it may be a male-to-male antagonistic signal or an advertisement to females.

More ‘gunshots’

Parks says the team used noninvasive acoustic monitoring to analyze gunshots at two locations on the Scotian Shelf over a two-year period. “The resultant data has provided tremendous insights into the whales’ feeding and mating habits.”

The gunshot sound production occurred mainly in the autumn and, more often than not, at night—information that is essential to not only the individual fitness of each whale, but also the survival of the species, in general.

The observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, says Jessica McCordic.

“Our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior, including possible mating activities,” she says, acknowledging David Mellinger, associate professor of marine bioacoustics at Oregon State University, who collected and provided access to the recordings used in the study.

“It also provides a better understanding of right whale behavior and what needs to be done with future conservation efforts.”

Source: Syracuse University

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