Ship strikes are a leading threat to large whales, with global shipping routes overlapping 92% of their habitats, a new study finds. But protecting whales in the most dangerous collision hotspots would require action over just 2.6% of the ocean’s surface, researchers conclude, potentially saving thousands of whales with minimal disruption to global trade.
The study looked at four of the largest and most impacted whales: blue (Balaenoptera musculus), fin (B. physalus), humpback (Megaptera novaeangliae) and sperm whales (Physeter macrocephalus). Researchers overlapped locations of 430,000 recorded sightings of these whales with the courses of 176,000 cargo ships to pinpoint high-risk areas for whale collisions.
The endangered blue whale, the largest animal ever to live, was found to be disproportionately impacted around the Azores Islands, the West Coast of the U.S. and around the southern tip of India. Meanwhile, humpbacks, famous for their haunting songs, are at highest risk along South Africa’s coast and between China and Taiwan.
“We were surprised by the lack of protective measures that are in place for guarding whales against these collisions with vessels,” Briana Abrahms, the study’s senior author and an assistant professor at the University of Washington, U.S., told Mongabay by phone. “Our study is really a big first step in identifying where across the world we need to be focusing our eyes.”
Researchers found that mandatory measures to reduce collisions, including introducing the scientifically backed safe speed limit of under 10 knots (19 kilometers per hour or 12 miles per hour), or closing high-risk areas, were rare. Restrictions overlapped with just 0.54% of blue whale hotspots and 0.27% of humpback hotspots.
Today, most ships don’t even realize when they’ve hit whales, and an estimated 80% of ship collisions go undocumented, Abrahms said. “There’s so much opportunity to improve the situation, as there haven’t been any measures to protect these whales in the past,” she added.
Shipping traffic also creates noise and chemical pollution, making it harder for whales to find food and mates in the ocean. Rerouting vessels away from whale habitats and setting up alert systems to warn authorities and crews when whales are nearby could also be implemented, the researchers write.
More than 95% of the hotspots were along countries’ coastlines, where whales also often go to breed or feed on krill. This can make it easier for countries to set up protections independently, researchers say.
“Trade-offs between industrial and conservation outcomes are not usually this optimal,” co-author Heather Welch, a researcher with the National Oceanic and Atmospheric Administration, said in a statement. “There is a potentially large conservation benefit to whales for not much cost to the shipping industry.”
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This article by Shanna Hanbury was first published by Mongabay.com on 21 November 2024. Lead Image: Global shipping routes overlap 92% of the range of the blue, sperm, fin and humpback whales. Image courtesy of Asha de Vos.
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