The first day of 1986 marked the start of one of the environmental movement’s greatest campaign successes: a ban on commercial whaling.
Forty years on from this landmark, many whale species are facing a deadly and growing threat. Collisions with ships, from small ferries to vast container vessels, are now the leading cause of death for large whales. These include blue, fin, humpback and sperm whales.
Whaling is thought to have killed and processed an estimated 2.9 million large whales during the 20th century. The industry left several species on the brink of extinction.
Following the global “Save the Whales” campaign and public outcry, hunting of these marine mammals stopped in all but a few outlier countries. The ban has allowed populations of many species to recover, particularly humpback, grey and bowhead whales.
These recovering populations are particularly at risk from ships, however. Behaviours such as surfacing to feed and breath, slow movement, and a reliance on sonic over visual information all expose them to danger.
Estimates vary on the number of whales killed by ship strikes. In 2020, the International Whaling Commission (IWC) analysed its own ship-strike database to conclude that 605 “definite” strikes occurred between 1820 and 2019. Meanwhile, researchers working at the University of California, Santa Barbara, think some 20,000 whales are killed each year. They say deaths are concentrated in locations where migratory routes and busy shipping lanes overlap, such as California’s coastal waters.
Data on ship strikes is thought to be a huge underestimate. Collisions between whales and large ships are often undetected, while carcasses of large species disappear down to the ocean floor. In its 2020 analysis, the IWC concluded that “ship strikes are notoriously underreported and underestimated.”
If action to prevent collisions is not stepped up, conservationists fear the worst for species whose populations are already on the edge. That includes the critically endangered North Atlantic right whale, which has only 400 individuals remaining.
Dialogue Earth consulted Michael Moore, who directs the Woods Hole Oceanographic Institution’s Marine Mammal Center in the US. He says ship strikes are especially risky for species with small populations, but the threat is “very significant” for all large whale species.
“Humpback whales are less endangered than North Atlantic Right whales, but the premature loss of individuals – of any species – undercuts their ability to thrive,” says Moore.
Speed kills
Efforts to reduce the risk ships pose to whales have typically involved vessels avoiding locations known to be frequented by the animals, and slowing down, giving whales time to move, or at least lowering the force of collisions.
In 2022, a group of researchers in the US published their analysis of seasonal voluntary speed reductions on the east coast of North America, which were designed to protect North Atlantic right whales. They concluded that, when ships reduced speeds to 10 knots or less, the risk of fatal collisions fell by 50%. This compares to an almost 90% chance of a fatal collision for speeds of over 15 knots. But the study also says not enough ships complied with the voluntary rules, meaning the collision rate is likely still too high for the North Atlantic right whale to avoid extinction.
One study suggests that a 10% reduction in speed across the global shipping fleet could reduce the risk of whale collisions by around 50%. It points out this would also cut greenhouse gas emissions and noise pollution.
Campaigners want to see a global expansion of ship re-routing and speed reductions. According to a 2024 collision-risk study led by the University of Washington, US, this type of protection currently covers less than 7% of collision hotspots – those areas of the ocean where the risk of a collision is within the top 1% globally.
The study also found that mandatory – as opposed to voluntary – measures to protect whales in these hotspots were basically non-existent. The authors noted that expanding vessel speed limits across an additional 2.6% of the ocean’s surface would cover all collision hotspots.
Many NGOs want regulation rather than voluntary measures. The International Fund for Animal Welfare (IFAW) and others are campaigning for a mandatory 5-10% reduction in vessel speeds in all European waters.
“Shipping companies tell us that voluntary measures don’t work because they distort competition. Clients will always choose the fastest company so, if they apply voluntary speed reductions, they will be shooting themselves in the foot,” says Aurore Morin, a marine conservation campaigner at IFAW.
Others disagree, including the vice president for environment and climate at the World Shipping Council (WSC), Bryan Wood-Thomas. A member of the International Whaling Commission’s expert panel on vessel strikes, Wood-Thomas says reducing speed and closing areas to ships is not always practical. He cites proposals for mandatory ship rerouting in the US to avoid the Santa Barbara Channel off the California coast, which were not possible due to a nearby naval testing area.
Wood-Thomas also says many ships produce significantly more air pollution when travelling below 10 knots. Design changes could reduce this, but it would take many years to be effective due to the long lifetime of most vessels.
One challenge for ship operators is having information about routing and speed measures at their fingertips, particularly in areas where this can change depending on whale activity.
In 2023, the WSC launched the Whale Chart. This voyage planning aid consolidates all that information in one place for the first time. The organisation now wants to digitise this and enable automatic information downloads for new areas. Wood-Thomas says this would be “a huge step forward”.
Techno-fix scepticism
Recent years have seen the launch of a plethora of technology-based solutions to ship strikes. These are typically aimed at detecting whales more effectively than using spotters on ships to alert navigators. In theory, these could allow ships to continue moving through waters commonly frequented by whales without slowing down.
Researchers at Rutgers University in the US have combined underwater robots with acoustic sensors and artificial intelligence to help reroute cargo ships away from whales.
The Woods Hole Oceanographic Institute is also developing acoustic whale-detection technology.
Another product under development at the institute uses thermal imaging to detect whale breath. Identifications are verified before being passed onto ship captains, according to Daniel Zitterbart, an associate scientist at the institute. His team has developed thermal-imaging technology, the use of which has proliferated from 89 whale detections in 2019 to more than 50,000 in 2024.
Shipping companies want to implement nice, shiny technologies instead of the operational changes that we know workAurore Morin, International Fund for Animal Welfare
Though it is not possible to interpret from that exactly how many whales are being avoided, future research could analyse the circumstances where detection did not lead to evasive action, says Zitterbart.
Some think such technologies are often overhyped. Experts maintain that technology needs to be used in tandem with operational changes.
“Shipping companies want to implement nice, shiny technologies instead of the operational changes that we know work,” says Morin, who calls them “nice diversions”.
Such technologies may only work effectively during the daytime. They can also fail to provide sufficient notice for large ships such as container vessels, Morin adds, because these need 30-40 minutes to change direction.
Tracking the problem
As shipping and whale numbers continue to grow, gathering data on their overlap is vital to understanding the problem and potential solutions.
IFAW’s Whale Alert mobile app enables users to report and track whale sightings to authorities and shipping vessels. It estimates the risk of a collision and has been operational in North America since 2012, where it has been downloaded 150,000 times and logged around 30,000 whales. After launching in Europe in June last year, there have been several thousand downloads so far, according to Morin.
Though measuring avoided collisions is challenging, IFAW is researching how it could be done. “It’s important to note that improving our ability to detect and predict marine mammal presence is still itself very limited – and efforts like Whale Alert also improve this knowledge the more widely they are used,” says Morin.
Recorded sightings are sent automatically to a central database, which biologists can use to better understand whale presence, and feeding and migration patterns. The International Whaling Commission and other groups are also working to improve data collection on incidents.
Dialogue Earth spoke to Ellie Besley-Gould, chief executive of the Sustainable Shipping Initiative, a non-profit trying to bring together NGOs and the shipping industry. She confirms there is no industry-wide mechanism for reporting whale collisions.
Besley-Gould believes better data will help push shipping companies into doing more to reduce whale strikes. For example, firms will be able to use the data to meet corporate targets to reduce biodiversity impacts: “There’s more pressure on this issue for cargo and container ships, because [those] buyers are customer-facing brands and they’re interested in driving progress.
“No-one wants to hit a whale, but you’ve got to be able to prove the impact of measures taken to avoid that.”
Forty years after hunting them was banned, whales once again need human intervention. But as global shipping routes continue to grow apace, and with low public awareness this time around, it is not clear that help will come in time.
