A new study reveals that proposed deep-sea mining operations could impact the habitats of 30 species of sharks, rays, and chimaeras, also known as ghost sharks. The research highlights a significant overlap between areas targeted for mineral extraction and the ecosystems these cartilaginous fish depend on, creating a new potential threat to already vulnerable marine life.
The study, published in the journal Current Biology, was led by oceanographers at the University of Hawai’i at Mānoa. Researchers overlaid global species distribution maps from the International Union for Conservation of Nature (IUCN) Shark Specialist Group with mining contract and exploration areas regulated by the International Seabed Authority. Their findings indicate that nearly all 30 identified species could be affected by sediment plumes from mining, and 25 of those species face risks from direct disruption of the seafloor itself. This development adds a new layer of concern for a group of animals already facing significant threats worldwide.
An Emerging Threat to Vulnerable Populations
Sharks and their relatives are the second most threatened group of vertebrates on the planet, with overfishing and bycatch being the primary drivers of their decline. The study emphasizes that deep-sea mining introduces a new and significant stressor. Nearly two-thirds of the 30 species whose habitats overlap with mining areas are already facing a higher risk of extinction. The addition of mining activities could therefore accelerate their decline, potentially pushing some species toward local or global extinction.
The species identified in the study range from well-known animals like the whale shark and manta ray to lesser-known deep-sea dwellers such as the pygmy shark, chocolate skate, and various species of ghost sharks. Many of these animals are highly mobile and utilize a wide range of ocean depths, which increases their potential exposure to mining impacts that can span vast areas of the water column. The research underscores the need to consider these new threats in global conservation strategies.
Mechanisms of Harm from Mining Operations
Deep-sea mining poses a dual threat to marine life through both direct and indirect impacts. The primary methods target polymetallic nodules and other mineral-rich deposits on the abyssal plains, such as in the Clarion-Clipperton Zone of the Pacific Ocean, a key area of focus for potential mining.
Seafloor Disruption and Habitat Destruction
The most direct impact comes from mining vehicles and equipment operating on the ocean floor. These machines would scrape and disrupt the seabed, destroying the habitat where many deep-sea species live and feed. This is particularly dangerous for species like skates and chimaeras, which lay their eggs directly on the seafloor. Mining vehicles could destroy these sensitive nursery habitats, directly impacting the reproductive success and survival of the next generation.
Sediment Plumes and Water Column Impacts
Beyond the immediate mining sites, the operations would generate large plumes of sediment that are discharged into the water. These suspended particles can travel long distances, reducing water quality and clarity. The sediment can smother benthic organisms and disrupt the sensory cues that sharks and rays use for hunting and navigation. For filter feeders and other species, the cloudy water could make it difficult to breathe and find food, creating a widespread ecological footprint that extends far beyond the physical mining area.
Unique Biological Vulnerabilities
The life histories of many deep-sea sharks and their relatives make them exceptionally vulnerable to environmental disturbances. Unlike many other fish, these species are often characterized by slow growth rates, late maturity, and low reproductive output. This means that once a population is depleted, it can take an exceptionally long time to recover, if at all. The stable, slow-paced environment of the deep sea has shaped these biological traits over millennia, leaving the animals ill-equipped to handle rapid and large-scale habitat changes.
The study took these factors into account when assessing risk, analyzing not just the location of the species but also their reproductive strategies and how deep they dive. The combination of these biological characteristics and the direct threats from mining operations creates a heightened risk of long-term, irreversible damage to these unique populations.
A Call for Proactive Conservation
In light of their findings, the researchers are calling for stronger regulations and proactive conservation measures to protect vulnerable species from the potential impacts of deep-sea mining. Lead author Aaron Judah, a graduate student at the University of Hawai’i at Mānoa, stated that identifying and calling attention to this threat could help support healthy shark, ray, and chimaera populations in the future. The authors provide several recommendations for policymakers and regulatory bodies like the International Seabed Authority.
The recommendations include establishing comprehensive monitoring programs to track the health of these species, formally including sharks and their relatives in environmental impact assessments for all mining projects, and creating protected areas to safeguard critical habitats from mining activities. Experts argue that current frameworks must be updated to explicitly account for the risks posed by mining to ensure that this emerging industry does not worsen the ongoing global extinction crisis facing these vital marine predators.