The rush to mine the deep ocean is no longer a distant possibility. It’s here, thanks to global demand for minerals like cobalt and nickel rising, meaning governments and corporations are eyeing the seabed as a new frontier for resource extraction. Framing it as a way to meet the growing demand for batteries and renewable energy infrastructure, the above-mentioned metals are essential for batteries and renewable energy… but tapping into the deep sea to obtain them comes with risks far greater than those posed by terrestrial mining. Beneath the promise of a “green” solution lies a huge problem: deep-sea mining could irreversibly damage ecosystems we are only just beginning to understand. New evidence shows that sharks, rays and their relatives — collectively known as Chondrichthyans — may be among the overlooked casualties of this industrial frontier, which would be a disaster for the species that already rank among the most endangered vertebrates on Earth.
First, we need to talk about how what the scale of what is being proposed is staggering. Current exploration contracts granted by the International Seabed Authority, the UN body that regulates activities in the high seas, cover over a million square kilometers of ocean floor — that’s an area more than 14 times larger than all land-based mining operations combined. The three major targets for extraction are polymetallic nodules scattered across the abyssal plains, cobalt-rich crusts on seamounts and sulfide deposits around hydrothermal vents. Each of these ecosystems hosts unique biodiversity, much of it poorly studied. Some habitats, like deep-sea vents, have only recently been discovered as shark and skate nurseries. Losing them before we fully understand their role in marine life cycles would be an irreversible mistake.
Thus, the ISA faces an unenviable challenge. On paper, its mandate is to ensure that mining proceeds in a way that both allows nations to share in the resources of the seabed and protects the marine environment. In practice? Well, it operates under intense pressure. Developing nations argue that access to seabed minerals is essential for their economic growth. Industrialized nations and corporations want to secure a supply of metals for green technologies. Small island states like Nauru have triggered clauses in the ISA’s charter that force regulators to speed up the creation of mining rules. The result is a race against time, where economic and political urgency often eclipses ecological caution.
Scientists of all sorts of different backgrounds and expertise warn that this approach is deeply flawed. Many of the environmental assessments submitted to the ISA by contractors focus on microorganisms or benthic communities but overlook larger predators like sharks and rays. Yet, it’s crucial to remember that these species play critical ecological roles as top predators and mid-level consumers, shaping the flow of energy in deep-sea ecosystems. If they are lost, entire food webs could unravel. And because many Chondrichthyans are slow to mature and produce few offspring, their populations are especially ill-equipped to recover from industrial disturbances. Which is what makes a recent assessment all the more worrying, after it revealed that 30 species of sharks, rays and chimeras overlap with areas earmarked for mining in international waters, also known as Areas Beyond National Jurisdiction. These aren’t fringe habitats for these animals; for some species, more than half of their depth range overlaps with projected mining footprints. And out of the 30 species, nearly two-thirds are already threatened with extinction.
The risks come through two main pathways. The first is direct disturbance on the seafloor itself. Collector vehicles scrape or suction polymetallic nodules, sulfides or crusts from the seabed, generating clouds of sediment while removing habitat that some species depend on. For example, catsharks are known to attach their egg cases to deep-sea corals, while certain skates use coral gardens as nurseries. Disturbing these structures could wipe out future generations before they hatch! One species, the chocolate skate (Rajella bigelowi), faces especially high vulnerability, with 75 percent of its depth range overlapping with planned mining areas. The second threat comes from mining discharges in the midwater column. Sediment plumes released back into the ocean can spread over hundreds of kilometers and linger for months. For filter-feeding animals such as whale sharks and devil rays, these plumes could clog their delicate feeding structures, impairing their nutritional intake/uptake and expose them to heavy metals. Other species that rely on sight or bioluminescence to hunt in the darkness may find themselves blinded in a haze of suspended sediment. Even mobile predators like the cookiecutter shark (Isistius brasiliensis), which migrates vertically to feed, could encounter plumes during daily movements, leading to stress or reduced foraging success.
The geographic overlap between mining zones and shark habitats is also global, so no one area is safe. The Clarion-Clipperton Zone in the Pacific, home to polymetallic nodules, is particularly concerning because it coincides with the ranges of highly migratory species like the whale shark. Elsewhere, seamounts targeted for cobalt-rich crusts are nurseries for benthic and egg-laying species. Hydrothermal vents that might be mined for polymetallic sulfides have recently been found to serve as incubation areas for deep-sea skates. Every single one of these habitats represents a unique and irreplaceable role in the survival of chondrichthyans.
There are some mitigation measures are on the table. For instance, simulations suggest that releasing mining discharge plumes below 2,000 meters (or even at the seabed) could reduce overlap with pelagic species that swim in shallower waters. But even this comes with trade-offs, since concentrating waste near the seabed could worsen impacts on stationary or egg-laying animals. Area-based protections, like the “Areas of Particular Environmental Interest” already designated in the Clarion-Clipperton Zone, could help safeguard key ecosystems, but their effectiveness depends on accurate mapping of species distributions… something we still lack for much of the deep sea.
The truth is, we are attempting to regulate an activity before we have a complete picture of what is at stake. New species of sharks, rays and chimeras are still being discovered, and many remain poorly studied. Without strong baseline data on where these animals live, how they reproduce and how they use the deep ocean, any environmental assessment will underestimate the true risks. Mining could damage ecosystems that have taken millions of years to form before we even know they exist.
I’ve heard deep-sea mining being called a test of humanity’s ability to manage the global commons responsibly. I couldn’t agree more because or sharks and rays, the outcome could be the difference between survival and extinction. As the ISA moves closer to finalizing regulations, the scientific community is (rightfully) urging caution. Their recommendations include improving baseline monitoring of deep-sea predators, expanding protected areas near mining zones and rethinking how and where discharge plumes are released. Above all, they stress the importance of taking a precautionary approach and delaying large-scale operations until we can assess their full ecological costs.
The ocean’s oldest predators are already under immense pressure from overfishing and climate change. Adding a new industrial threat without adequate safeguards risks pushing them over the edge. The race for deep-sea metals may power our renewable future, but if done recklessly, it could come at the expense of species that have shaped marine ecosystems for over 400 million years.
