Photo/Illutration Hermit crab shells are seen piled up inside an abandoned tire dumped in the ocean. (Provided by Atsushi Sogabe)

Car tires abandoned on the seabed are creating inescapable traps for hermit crabs, leading to slow or even brutal deaths of the “cleaners of the ocean,” researchers at Hirosaki University in Aomori Prefecture said.

The tires are another example of how reckless human activity can lead to an endless cycle of destruction in the seas.

Fishing nets and other “ghost gear” left in the oceans have long been killing marine life.

The university research team, in a report published in October, said discarded tires are also damaging the marine ecosystem by destroying hermit crabs, which purify water and sand.

The study started after Atsushi Sogabe, an associate professor at the university, noticed many sea snail shells and hermit crabs in the interior of a discarded tire.

The researchers sank six tires into the ocean for an experiment, and a total of 1,278 hermit crabs had gotten inside the tires in a year.

Although the researchers saw some hermit crabs gaining entry into the tires, none of them was able to come out.

When the hermit crabs tried to escape the tire, likely in search of larger shells to fit their growing size, they moved along the wall of the interior. But the tire’s recurve kept the crabs stuck inside.

Many hermit crabs found inside the tires had damaged shells.

“Trapped in an environment with poor resources like the tire’s interior, they might have been fighting for shells or cannibalizing each other for food,” Sogabe said.

Although it remains unknown how each tire specifically affects the environment, abandoned tires continue to be found during marine cleanups.

Sogabe says that the issue cannot be ignored and has called for countermeasures.

The team’s study was published in the Royal Society Open Science at (https://royalsocietypublishing.org/doi/10.1098/rsos.210166).

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The damaged shells of hermit crabs inside an abandoned tire indicates they likely cannibalized each other or struggled to find larger shells for their growing bodies. (Provided by Atsushi Sogabe)

‘MOST DEADLY’ PLASTIC DEBRIS

In a report published in 2016, a British environment research company estimated that more than 1 million tons of “ghost gear,” such as fishing nets and ropes, are illegally discarded or lost at sea every year.

The equipment keeps trapping and killing marine life in a phenomenon known as “ghost fishing” because the fishermen are long gone from the areas.

The Environment Ministry in a report compiled in 2018 said fishing nets and ropes accounted for 41.8 percent of the weight of plastic waste washing up on Japan’s shores, followed by buoys at 10.7 percent.

According to the Global Ghost Gear Initiative (GGGI), an international project comprising governments, companies and nongovernmental organizations, 5 to 30 percent of the world’s fish stocks are threatened by ghost fishing.

If the issue is left unresolved, the pollution could also affect tourism and marine traffic.

The vaquita, a small dolphin living in the Gulf of Mexico, has been pushed to near-extinction by ghost fishing and bycatch in gillnets.

A report released in 2019 by the International Committee for the Recovery of the Vaquita (CIRVA) said there were only 10 vaquitas in existence as of 2018.

The World Wildlife Fund for Nature (WWF) pointed to the urgency of taking countermeasures in its report published in October 2020 (https://www.worldwildlife.org/publications/stop-ghost-gear-the-most-deadly-form-of-marine-plastic-debris).

The need for fisheries is ever-increasing. Marine products are becoming an increasingly important source of protein as the global population keeps growing.

The WWF refers to ghost gear as “the most deadly form of marine plastic debris.”

The organization is pushing for measures to prevent the loss of fishing gear by designing equipment that is traceable through marking.

It also calls for development and use of fishing gear made with biodegradable materials that are less environmentally damaging even if they are lost at sea.

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