The deadly collision of whale sharks with ships is greatly underestimated

This content was published on May 09, 2022 – 19:02

Science Writing, May 9 (EFE).- The number of whale sharks has decreased in recent years in many places, but it is not entirely clear why. Now, a new study indicates that the collisions of these animals with large ships are greatly underestimated.

The observational study, published in the journal PNAS, has been carried out using satellite tracking data from almost 350 whale sharks. The research team has been led by scientists from the UK Marine Biological Association and the UK’s University of Southampton.

Since these animals spend a lot of time in surface waters and gather in coastal regions, experts have theorized that collisions with ships could be causing significant deaths in whale sharks, but until now there was no way to control it.

Scientists from 50 international research institutions and universities followed the movements of whale sharks and ships around the world to identify risk zones and potential collisions.

The team mapped shark “hotspots” that overlapped with the world’s fleets of cargo, oil, passenger and fishing vessels – the kinds of large vessels capable of hitting and killing a whale shark – to reveal that more than 90% of whale shark movements “fell under the footprint” of shipping activity.

In addition, these spent almost half of their time in surface waters at depths similar to those of ships.

The study showed that whale shark tag transmissions ended more frequently than expected on the busiest shipping lanes, even when technical glitches were ruled out.

The team concluded that the loss of transmissions was likely due to whale sharks being hit, killed and sinking to the bottom of the ocean.

University of Southampton researcher Freya Womersley says: “The shipping industry, which allows us to source a wide variety of everyday products from around the world, may be causing the decline of whale sharks, which are a hugely important species. in our oceans.

They are slow-moving ocean giants that can grow up to 20 meters in length and feed on microscopic animals called zooplankton.

Whale sharks help regulate ocean plankton levels and play an important role in the marine food web and in the health of ocean ecosystems.

Professor David Sims, founder of the Global Shark Movement Project, said: “Incredibly, some of the marks that record depth, as well as location, showed whale sharks moving towards shipping lanes and then slowly sinking into the ocean. seabed hundreds of meters deep”.

“It’s sad to think that there have been so many deaths of these amazing animals around the world from ships without us realizing it to take preventative action,” says Sims.

There are currently no international regulations to protect whale sharks from collisions with ships.

The team, which also includes the Spanish Carlos Duarte, from the King Abdullah University of Science and Technology (Saudi Arabia), affirms that this species faces an uncertain future if measures are not taken soon. EFE

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