13 Jul 2023

Deep-sea mining threatens tuna fisheries - study

5:34 pm on 13 July 2023
Abstract abyss under sea background. coral reef underwater with sun ray. 3D rendering image.

Abstract abyss under sea background. coral reef underwater with sun ray. 3D rendering image. Photo: Copyright: isampuntarat

Seafood organisations are calling for a pause on deep-sea mining after a new study claims the two industries could be in conflict as tuna migrates East due to climate change.

The seafood groups - including the Global Tuna Alliance, whose industry partners account to roughly a third of the global tuna trade - said deep-sea mining "poses a threat to the ocean and its inhabiting life".

The announcement comes as the International Seabed Authority (ISA), the UN agency that is responsible for regulating the world's ocean floor, meets in Jamaica, where member countries are expected to advance negotiations for mining regulations.

The letter, that included six other organisations, said they "strongly recommend a pause on deep-sea mining until there is a clear understanding of the impacts the industry may have on the marine environment, its living resources, and those dependent on them".

"We see it as mandatory that strong, scientifically-grounded regulations are in place before any exploitation contracts are granted by the International Seabed Authority."

The study published in Nature npj Ocean Sustainability said tuna fisheries and deep-sea mining could increasingly overlap as more tuna moves into the Clarion-Clipperton Zone of the Pacific Ocean - a high interest area for deep-sea mining companies.

According to the study, the total bio-mass for bigeye, skipjack and yellowfin tuna in the Pacific's Clarion-Clipperton Zone is predicted to increase between 10 to 31 percent by mid-century as global temperatures increase.

Lead author Diva Amon said plumes created by the mining could impact the behaviour of tuna.

"If deep-sea mining is happening in that area, where they are going for climate refuge may actually be very inhospitable to them," Amon said.

"This could be deeply problematic for management of the high seas in the future, and also potentially have implications for economies, wellbeing's, livelihoods and of course biodiversity."

Amon said plumes might cause tuna to migrate away from the area as well as cause illness.

She said the noise of the mining could also have a physiological and behavioural impact on tuna and toxic metals could enter the seafood supply.

"This plume potentially could contain metals, some of which could be toxic and that could actually become incorporated into the deep-sea food web," she said.

"Even if there are only low risks from this accumulation it could still have a negative consumer reaction.

"So, there are potentially be implications to economies and for Pacific small island developing states or coastal Pacific states that fish in the area."

Amon added there could be physical conflict as both fishing and deep-sea mining vessels complete in the same area.

The seafood organisations have joined the call for a moratorium alongside several countries in the recent weeks, including Canada, Sweden, Ireland and Switzerland.