KINGSTON, R.I. — Nov. 22, 2024 — Each year, thousands of whales are injured or killed 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 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, “Ship collision risk threatens whales across the world’s oceans,”published in Science, researchers report that global shipping traffic overlaps with about 92% of these whale species’ ranges.

“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 University of Washington 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 most pressing problem with ship collisions in the North Atlantic is the critically endangered North Atlantic right whale, with four known to be killed by ships in 2024 out of a population of around 370,” said co-author Bob Kenney, an emeritus marine research scientist at URI’s Graduate School of Oceanography. Kenney has contributed over 41,000 whale sightings from the extensive database he has curated since 1986. “One of those was a nursing mother, so its dependent calf could not have survived. While the species was not included in the new global study because of its limited distribution, it’s another example of the threat posed by ship collisions with whales.”

The research 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.

“As much as we found cause for concern, we also found some big silver linings,” said senior author Briana Abrahms, a University of Washington assistant professor of biology and researcher with the Center for Ecosystem Sentinels. “For example, implementing management measures across only an additional 2.6% of the ocean’s surface would protect all of the highest-risk collision hotspots we identified.”

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

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.

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. 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.

“Lowering vessel speed in hotspots also carries additional benefits, such as reducing underwater noise pollution, reducing greenhouse gas emissions, and cutting air pollution, which helps people living in coastal areas,” said Nisi.

The authors hope their global study could spur local or regional research to map out the hotspot zones in finer detail, inform advocacy efforts and consider the impact of climate change, which will change both whale and ship distributions as sea ice melts and ecosystems shift.

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.