Fewer than 7% of global hotspots for whale-ship collisions have protection measures in place

Ocean Wise data contributes to new paper, published in Science, on global whale-ship collisions

According to the fossil record, cetaceans — whales, dolphins and their relatives — evolved from four-legged land mammals that returned to the oceans beginning some 50 million years ago. Today, their descendants are threatened by a different land-based mammal that has also returned to the sea: humans.

Thousands of whales are injured or killed each year after being struck by ships, particularly the large container vessels that ferry 80% of the world’s traded goods across the oceans. Collisions are the leading cause of death worldwide for large whale species. Yet global data on ship strikes of whales are hard to come by — impeding efforts to protect vulnerable whale species. A new study published in Science has for the first time quantified the risk for whale-ship collisions worldwide for four geographically widespread ocean giants that are threatened by shipping: blue, fin, humpback and sperm whales.

In the paper, published online November 21, 2024 in Science, researchers report that global shipping traffic overlaps with about 92% of these whale species’ ranges. The international team behind the study, which includes researchers across five continents, looked at the waters where these four whale species live, feed and migrate by pooling data from disparate sources — including government surveys, sightings by members of the public, tagging studies and even whaling records. The team collected some 435,000 unique whale sightings. They then combined this novel database with information on the courses of 176,000 cargo vessels from 2017 to 2022 — tracked by each ship’s automatic identification system and processed using an algorithm from Global Fishing Watch — to identify where whales and ships are most likely to meet.

Ocean Wise Whales Initiative Director, Dr. Chloe Robinson, and former Ocean Wise Research Scientist Lauren Dares are authors on the study, and provided data and insight on whale observations curated in Ocean Wise Sighting Network (OWSN)’s 20+ year dataset. This data included observations of large whale species, namely humpback, fin, blue, and sperm whale reported throughout Washington State, British Columbia, and Alaska.

“It is fantastic to see how data from the Ocean Wise was used to identify hotspots of ship strike risk for large whale species in Pacific northeast waters. Leveraging the data for this study we hope will ultimately contribute to the implementation of new management measures in high-risk areas for whales,” said Dr. Chole Robinson, Director of the Ocean Wise Whales Initiative.

“Whale-ship collisions have typically only been studied at a local or regional level — like off the east and west coasts of the continental U.S., and patterns of risk remain unknown for large areas,” said lead author Anna Nisi, a UW postdoctoral researcher in the Center for Ecosystem Sentinels. “Our study is an attempt to fill those knowledge gaps and understand the risk of ship strikes on a global level. It’s important to understand where these collisions are likely to occur because there are some really simple interventions that can substantially reduce collision risk.

The team found that only about 7% of areas at highest risk for whale-ship collisions have any measures in place to protect whales from this threat. These measures include speed reductions, both mandatory and voluntary, for ships crossing waters that overlap with whale migration or feeding areas.

Those highest-risk areas for the four while species included in the study lie largely along coastal areas in the Mediterranean, portions of the Americas, southern Africa and parts of Asia.

The study uncovered regions already known to be high-risk areas for ship strikes: North America’s Pacific coast, Panama, the Arabian Sea, Sri Lanka, the Canary Islands and the Mediterranean Sea. But it also identified understudied regions at high risk for whaleship collisions, including southern Africa; South America along the coasts of Brazil, Chile, Peru and Ecuador; the Azores; and East Asia off the coasts of China, Japan and South Korea.

The team found that mandatory measures to reduce whale-ship collisions were very rare, overlapping just 0.54% of blue whale hotspots and 0.27% of humpback hotspots, and not overlapping any fin or sperm whale hotspots. Though many collision hotspots fell within marine protected areas, these preserves often lack speed limits for vessels, as they were largely established to curb fishing and industrial pollution.

For all four species the vast majority of hotpots for whale-ship strikes — more than 95% — hugged coastlines, falling within a nation’s exclusive economic zone. That means that each country could implement its own protection measures in coordination with the U.N.’s International Maritime Organization.

Of the limited measures now in place, most are along the Pacific coast of North America and in the Mediterranean Sea. In addition to speed reduction, other options to reduce whale-ship strikes include changing vessel routings away from where whales are located, or creating alert systems to notify authorities and mariners when whales are nearby.

The Ocean Wise Whale Report Alert System (WRAS) is one such mitigation tool. The WRAS is a cutting-edge conservation tool designed to protect whales from ships strikes and disturbance by alerting mariners to their presence in real-time. The WRAS is informed by a combination of local sightings networks and automated detections from infrared cameras and hydrophones. These data are transmitted to ships in real-time, enabling mariners to take proactive measures to avoid collisions with whales. 

“The Whale Report Alert System is a tool designed to mitigate ship strikes. Since its launch in 2018, there have been over 60,000 WRAS alerts sent to commercial vessels, helping to mitigate over 200,000 encounters for ship strike risk. As this study shows, ship strikes are a global issue and threat to the health and survival of not only the four large whale species focused on in this study, but all large whale species worldwide. We know strategies like speed reduction can work, and we believe the WRAS is a valuable tool that can be used both in conjunction with existing measures and implemented in new, unmanaged geographies to dramatically reduce ship strikes” said Dr. Robinson.

To learn more about how Ocean Wise is working to reduce ship strikes, visit ocean.org/whales/wras/.

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Co-authors on the study are Stephanie Brodie, a research scientist with the Commonwealth Scientific and Industrial Research Organisation in Australia; research scientists Callie Leiphardt and Rachel Rhodes, and professor Douglas McCauley, all at the University of California, Santa Barbara; Elliott Hazen, research ecologist with NOAA’s Southwest Fisheries Science Center; Jessica Redfern, associate vice president of the Anderson Cabot Center for Ocean Life at the New England Aquarium; the UW’s Trevor Branch, professor of aquatic and fishery sciences, and Sue Moore, a research scientist with the Center for Ecosystem Sentinels; André Barreto, professor at the Universidade do Vale do Itajaí in Brazil; senior research biologist John Calambokidis with the Cascadia Research Collective; data scientist Tyler Clavelle, chief scientist David Kroodsma and senior manager Tim White with Global Fishing Watch; research scientists Lauren Dares and Chloe Robinson with Ocean Wise; Asha de Vos with Oceanswell in Sri Lanka and the University of Western Australia; Shane Gero with Carleton University; biologist Jennifer Jackson with the British Antarctic Survey; Robert Kenney, emeritus research scientist with the University of Rhode Island; Russell Leaper with the International Fund for Animal Welfare; Ekaterina Ovsyanikova at the University of Queensland; and Simone Panigada with the Tethys Research Institute in Italy.

The research was funded by The Nature Conservancy, NOAA, the Benioff Ocean Science Laboratory, the National Marine Fisheries Service, Oceankind, Bloomberg Philanthropy, Heritage Expeditions, Ocean Park Hong Kong, National Geographic, NEID Global and the Schmidt Foundation.