Friday, November 22, 2024

Ship strikes kill thousands of whales. A study of hot spots could map out solutions

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A study of hot spots for collisions between ships and whales around the world, including Canadian waters, offers a map for measures to prevent the deadly strikes that could drive some species to extinction, one of the British Columbia-based authors says.

Chloe Robinson said reported strikes represent a fraction of their true extent, and a lack of protection measures leaves whales vulnerable as global shipping expands.

The study found shipping takes place across 92 per cent of the ranges for humpback, blue, fin and sperm whales worldwide, but measures to reduce vessel strikes have been implemented in less than seven per cent of high-risk areas.

“That could really spell, you know, potential extinction for some of these species,” said Robinson, director of whales for Ocean Wise, a B.C.-based organization that provided data for the paper published in the peer-reviewed journal Science.

“A recent study estimated anything up to 20,000 whales are killed a year through ship strikes, globally, and that’s just an estimate, a best-case estimate.”

Robinson said she was surprised to see Swiftsure Bank, off the west coast of Vancouver Island, emerge as a risk hot spot for strikes of fin, blue and humpback whales. The area is a “migration highway” for humpbacks, she noted.

The study also identified a hot spot for the same three species in the Gulf of St. Lawrence between Quebec, New Brunswick and Newfoundland.

“This is something that Ocean Wise has been looking into because a lot of the management measures occur offshore and not sort of within the Gulf of St. Lawrence itself and even the St. Lawrence Seaway, (which) leads down to the Great Lakes,” she said. “That was a huge hot spot, which was really interesting for me.”

Robinson said there have been smaller studies on the risk of ship strikes in different regions, but the study published Thursday is the first to map the distribution of the four whale species, using a variety of data sources, then compare it with the Automatic Identification System, a tool used for tracking vessels worldwide.

“This was really the first of its kind to map these two on top of each other,” she said.

The researchers found the highest levels of risk in the Indian, western North Pacific and Mediterranean, while it also identified high-risk areas in the eastern North Pacific, North and South Atlantic Ocean along with the South China Sea.

The Southern Ocean was the only region that did not contain any ship-strike hot spots due to low levels of shipping, despite high use by whales, the study found.

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