In a unique survey, researchers at the University of Washington analyzed data from 435,000 whale positions and over 35 billion positions from 176,000 cargo ships.
The results showed that almost all areas where the whales move are also heavily trafficked by ships. In addition, less than seven percent of vessels in high-risk areas have strategies to reduce the risk of collisions.
– We identified many high-risk areas where the problem was already known, but also that the risk is widespread far beyond these areas. It shows that the problem is large and covers large parts of the planet, says Anna Nisi, conservation ecologist and one of the study’s authors.
The risk is greatest near coasts
Blue whales, fin whales, humpback whales and sperm whales, which move over vast areas of sea, are most at risk of collisions near coasts. The mapping particularly points out the Mediterranean Sea, the Panama Canal, the eastern US coast and western Europe as areas of risk.
– On the west coast of the United States, an estimated 80 blue and humpback whales die each year as a result of collisions, which exceeds the sustainable limit by 2 to 8 times depending on the species, says Anna Nisi.
Slow down and use maps
To protect the whales, the researchers propose speed limits in high-risk areas, which could give the whales more time to avoid the ships and reduce the extent of damage in the event of a collision. They also suggest using the study’s mapping to alter ship routes and avoid key whale habitat.
– Reducing the ship’s speed also reduces underwater noise, which benefits many marine species. In addition, it reduces air pollution and greenhouse gas emissions, which is good for both the climate and public health, says Anna Nisi.
The future holds greater challenges
After commercial whaling almost ceased, the threat picture to whales has changed.
Ship collisions are now one of the biggest threats to these animals, and the problem may worsen. Maritime trade is expected to triple by 2050, which could lead to even more collisions if no measures are taken.