A new study, led by the UK’s Marine Biological Association and the University of Southampton, led by experts in Australia and New Zealand, found that industrial shipping may kill large numbers of whale sharks.
Marine biologists have said whale shark numbers have declined in recent years, but it’s not clear why.
But a new international study suggests that collisions with shipping traffic could be a major factor.
The researchers examined satellite data to track down about 350 whale sharks. They found that the world’s largest fish spend most of their time in waters used by cargo and other large ships.
The study showed that transmissions from tags that monitor their movements often end up in busy shipping lanes. The international team, including experts from Britain, Australia and New Zealand, believe that many sharks may have been killed by boat collisions before sinking into the ocean floor.
Mark Erdman is from the University of Auckland in New Zealand and a scientist at Conservation International, a non-profit environmental organization.
He co-authored the study, and believes shipping is a major threat to whale shark populations, which are a protected species.
“If we are protecting them from fisheries, why is their population still declining? and one consideration is the fact that these are big marine plankti vores Those that move relatively slowly, feeding on the surface, spend 50% of their time in the top 10–20 m of the water. So, it’s possible that they’re actually participating in a lot of global shipping. Now, the study finds that, in fact, there is a tremendous overlap between where whale sharks are going and global shipping traffic. So, those are real collision-risk areas,” he said.
Most fatal attacks are likely to go undetected or go unreported. Currently, there are no regulations in place to protect endangered whale sharks from these types of collisions.
Whale sharks play an important role in marine food webs and healthy marine ecosystems.
They can grow up to 20 meters long.
The study is published in PNAS – Proceedings of the National Academy of Science – magazine.