New study used ocean-floor listening devices to track endangered right whales

Post date: Nov 27, 2017 7:38:20 PM

A northern right whale and her calf off Duxbury Beach in 2015.

By Martin Finucane GLOBE STAFF NOVEMBER 20, 2017

Listening devices helped scientists determine that North Atlantic right whales are spending more time in the mid­Atlantic region. The tape was rolling. Woods Hole researchers used hundreds of acoustic devices on the ocean floor to develop evidence of shifts in the distribution of endangered North Atlantic right whales. Analyzing the sea creatures’ alien-sounding calls, the researchers found that the time the whales spend in the Bay of Fundy and greater Gulf of Maine appears to be decreasing, while it’s increasing in the mid-Atlantic region. More of the whales also seem to be gathering in Cape Cod Bay in recent years, said Genevieve Davis, an acoustician at the National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center Woods Hole Laboratory and lead author of the study. Davis said the cause of the shifts, also noted in visual surveys, is unclear. One possibility could be that rising temperatures are driving the whales’ prey elsewhere, so they are following their food. Another factor could be human impacts, such as ship noise, fishing gear entanglements, and seismic surveying that sends shock waves through the deep, Davis said. It’s not clear if the shifts are part of a long-term change, she said. The study, which was published recently in Nature Scientific Reports, warned that if the movements of the endangered species are changing, new measures to protect them might need to be put in place. “With recent studies finding the Gulf of Maine is the fastest-warming body of water in the world, it is not surprising to see distributional changes across marine species,’’ the study said. “Regardless of the factors influencing these changes in distribution, it is critical for management strategies to reflect new threats that may arise for this species as they move into regions outside of existing management areas.’’ The government can protect right whales by barring ships, or setting speed limits for them, in specified areas. The study said that “in an ocean where conditions are changing rapidly, adaptive management is needed to identify and protect areas that are crucial for species on the brink of extinction.’’ It suggested real-time monitoring of whale calls or a new approach beyond classifying the whales’ habitat as “static, confined areas.’’ The whales “really don’t fit in a box so we have to think about broader ranges for management,’’ said Davis. Davis said the study also filled gaps in the knowledge of whales’ whereabouts. Scientists knew that some whales were migrating to southern calving grounds during the winter and back to northern waters to feed in the summer. Davis said that left the question: Where were the rest of the whales? The research found that the whales were spread more widely than previously known, Davis said. In the winter, they were detected from Nova Scotia to Florida, while in the summer they were spread north of Cape Hatteras, N.C. “It’s a much larger range all year round than we originally thought,’’ she said. “The areas they occupy are much bigger.’’ The study used 324 listening devices placed by 19 organizations through the western North Atlantic. It analyzed data from 35,600 days, collected between 2004 and 2014, finding the changes in whale distribution beginning in 2010.

The changing migration of right whales

SOURCE: Adapted from Davis et al. 2017 Nature Scientific Reports, “Long-term passive acoustic recordings track the changing distribution of North Atlantic right whales (Eubalaena glacialis) from 2004 to 2014”