Conserving a Mere 2.6% of Ocean Areas Could Save Thousands of Whales Annually

Maritime transport, which today provides 90% of world trade, represents a growing threat to marine biodiversity. Collisions between ships and large whales, once decimated by industrial hunting, are now one of the main causes of mortality for these species, essential to marine ecosystems.

An international study, led by researchers from the University of California at Santa Cruz, the British Antarctic Survey and published in Science, draws up for the first time a global map of collision risks based on more than 435,000 observations of whales and 35 billion maritime journeys. It reveals that the vast majority of critical areas benefit from no protection. At a time when global warming is reshaping maritime routes, this mapping warns of an underestimated, but avoidable, ecological crisis.

Hotspots: an alarming map of the risks of collisions with whales

According to this new study, blue, humpback, Finn and sperm whales share their habitat with 92% of the world's shipping routes. In fact, this observation highlights a high risk of collisions. These risk areas are mainly concentrated along the coasts. Particularly in regions where traffic is dense, such as the Mediterranean basin, the Pacific Northwest and the American coasts.

However, hotspots are also identified in the open sea, near the Azores or in the Indian Ocean. The intersection between cetacean migration routes and maritime routes is critical. Based on 435,000 whale sightings crossed with 176,000 maritime routes between 2027 and 2022, the study reveals an alarming finding. Overall, less than 7% of risk hotspots for any of the four species were covered by voluntary measures. And less than 1% were covered by mandatory measures, such as reducing ship speeds, to limit risks.

Spatial overlap between whales and maritime traffic. © AC Nisi et al., 2024

Heather Welch, a researcher at the University of California at Santa Cruz and co-author of the study, emphasizes the difficulty of quantifying the scale of the problem. “ Most collisions are neither reported nor directly observed, complicating risk identification “, she explains. This opacity, combined with limited management, worsens the situation in crucial but underprotected regions such as the South American coasts or southern Africa. These gaps hinder the implementation of global strategies, even though simple solutions could considerably reduce the impacts on whale populations.

Solutions: targeted and effective coverage

Indeed, the study highlights an accessible solution to reduce the risk of collisions with whales. It would be “enough” to target management measures on only 2.6% of the ocean surface. This minimalist, but precise strategy would cover all areas identified as presenting a high risk of collision. Among the proposed interventions, reducing ship speed is proving particularly effective. Briana Abrahms, co-author of the study, explains that slowing ships in these critical areas does more than just reduce collisions. “ It also reduces underwater noise, which disturbs whales, as well as greenhouse gas emissions and air pollution. Benefits for marine ecosystems and coastal populations “, she declares. This holistic approach illustrates the potential for pragmatic and, above all, low-cost solutions for the maritime industry.

Local initiatives, such as the program Blue Whales Blue Skies in California, demonstrate that these targeted measures can have a significant impact. This program combines speed limits and monitoring of risk areas to protect the region's blue whales. However, on a global scale, efforts remain disorganized and unevenly applied, like many protection and conservation projects unfortunately.

The study reveals that 95% of critical areas are in exclusive economic zones (EEZ). In other words, national governments have the power to regulate maritime traffic. This offers a unique opportunity to strengthen protections through local initiatives, supported by the International Maritime Organization. And by avoiding the cumbersomeness of international negotiations on international waters. Targeted coverage, supported by national policies, could then guarantee effective and rapid protection for these ocean giants.

The challenge of climate change for whales

Add to this global warming which amplifies the risks of collisions between ships and whales. How ? By disrupting ocean and maritime dynamics. In the Arctic, the accelerated melting of ice is opening up previously inaccessible maritime routes. This intensifies traffic in previously preserved habitats. These regions, where whales move to feed and reproduce, are becoming new collision hotspots.

Predicting overall vessel strike risk at the species level for blue whales, fin whales, humpback whales and sperm whales. © AC Nisi et al., 2024

At the same time, climate change is modifying marine ecosystems, forcing whales to adapt their migratory routes and feeding areas. These movements make historical data on their habits less reliable for anticipating future risks. Areas once considered safe havens, far from maritime routes, could soon become hotspots for dangerous interactions.

Anna Nisi, co-author, emphasizes the need for a comprehensive and coordinated response to this emerging crisis. “ Whales do not recognize national borders. Protecting their migratory routes requires cross-border cooperation “, she explains. Nations must work together to monitor and protect migration areas. In particular, they must establish safe marine corridors and adjust international maritime routes. This coordination is all the more crucial as global warming risks inevitably increasing pressure on whales.

Source: Anna C. Nisi et al., “Ship collision risk threatens whales across the world's oceans”. Science 386,870 -875 (2024). DOI:10.1126/science.adp1950