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Rash of killer whale rammings on boats has some wondering: How do you stop an orca?

Not attacks, just playful teenagers: A multinational group of orca experts provides tips and ideas to prevent curious orcas from ramming vessels

Since 2020, more than 673, boats, expensive yachts, fishing boats and motorboats have been victims of a group of playful orcas ramming 鈥撎and in some cases sinking vessels in the crystalline waters off the coast of Spain, Portugal, 91影视 and Morocco.

What originally appeared to be attacks, now seem more likely to be a bunch of bored teenage orcas looking for something to do, said cetacean expert Alexandre Zerbini.

A multinational group of orca experts, sponsored by the governments of Spain and Portugal, met in February and released 听听the behaviors and what might be done to stop it.

What should be done to avoid orca interactions?

The workshop participants suggest mariners avoid areas where the Iberian killer whales are likely to be hunting their preferred prey 鈥 bluefin tuna 鈥 from May through August. They should also keep their boats closer to shore in shallow areas and move at least a mile away from any orcas who begin to interact with their boats. If possible, they should head toward shore to make rescue faster, should it be necessary.

Boaters are already following the experts' in areas where the killer whales are interacting with their vessels and the results are encouraging.

Now that vessels are fleeing immediately, rescues are down 80%, from May 2023 through May 2024, said Renaud de Stephanis. De Stephanis has been studying orca behavior for more than 25 years and is president of (Conservacio虂n, Informacio虂n y Estudio sobre Ceta虂ceos), an organization dedicated to preserving marine life.

During that same period, interactions (when an orca touches a vessel) have declined by 70%, he said.

Experts caution that more time will be needed to see if the incidents are indeed declining but are hopeful.

Devices suggested to deter the orcas from interacting with the boats

During the session in February, the group of experts also discussed devices or boat modifications to deter the orcas from interacting with the rudders.

De Stephanis says he's testing a rudder with an altered surface and appearance. The experimental device appears promising, particularly in limiting the number of rudders orcas target.

"The device features .5 inch conical protrusions on the hull and keel of sailboats," de Stephanis said. "The theory is that these protrusions alter the orcas' perception of the rudder, deterring them from attacking it."

The flowing pieces behind the rudder create the appearance of a jellyfish, which orcas detest and they avoid it, de Stephanis added.

While results were promising, testing halted in 2023 because Portuguese officials said they were concerned about potentially harming the orcas.

"This concern is unfounded," said de Stephanis. "Orcas have excellent underwater vision, but to avoid problems, we stopped temporarily." De Stephanis began retesting the device in June in collaboration with the National Fisheries Research Institute in Morocco. "We are now testing the device with two rudders one with the device and one without. We have 15 cameras underwater and what we find is that they approach the boat but that don't approach the rudder with the device," he said.

De Stephanis says he is seeking a patent on the device to keep it free for others to use. "I have a plan to patent it so no one can sell it and anyone can use it for free," he said.

Another possible deterrent called a hukilau, looks like a hanging torpedo-shaped weight in the water. The device has been effective in deterring whales from coming near fishing boats in Polynesia, but the group of orca experts agreed more tests are needed before it could be tried in the areas near the Strait of Gibraltar where many of the incidents have occurred.

Iberian orca interacting with a sailboat in the Iberian peninsula.

Pingers, also known as Acoustic Deterrent Devices, are another potential deterrent for cetaceans (whales, dolphins, and porpoises), but they don't appear to have a long-lasting impact on orcas.

When scientists tested pingers on orcas, the whales became familiar with the devices in less than five days, rendering them ineffective as deterrents, said de Stephanis.

"The same occurs with dolphins," de Stephanis said. "In our observations, it's evident that when we activate pingers in the water, dolphins still approach the boats. We can clearly see that they continue to come closer in all instances."

While de Stephanis believes rudder modification is the best deterrent, the group's only official recommendation has been to avoid areas where the Iberian killer whales might be and stay in shallow waters.

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