Recent European research coordinated by AZTI reveals protecting deep-sea fish is vital for climate and ecosystem stability
Mesopelagic Fisheries Study Highlights Climate Impact and Biodiversity Risks
Recent European research underscores the critical importance of protecting mesopelagic fish, which live in ocean depths between 200 and 1,000 meters. Findings from the five-year SUMMER project reveal that this largely untapped marine zone is vital for carbon sequestration, biodiversity, and potential pharmaceutical applications.
Key Climate Role of Mesopelagic Fish
The study, coordinated by the AZTI technology centre, found that mesopelagic fish facilitate the transport of approximately five billion tons of carbon dioxide equivalents annually through their daily vertical migrations. These movements represent a carbon transfer 1.5 times greater than the annual CO₂ emissions from the world’s automobiles.
“Mesopelagic species provide essential nutrient and climate regulation services and support numerous commercially important fish populations,” said Raúl Prellezo, AZTI fisheries economics expert and project coordinator. “At present, it is more beneficial to protect this area than to exploit it.”
Abundance and Biodiversity
The mesopelagic zone, often referred to as the “twilight zone,” contains an estimated 1.3 billion tons of biomass, representing 87% of the total pelagic biomass. Despite its abundance, researchers concluded that commercial fishing in this zone is economically unviable.
“Exploiting mesopelagic fish is limited by their small size, dispersed distribution, and low productivity,” said Prellezo. “These characteristics make the species particularly vulnerable to overfishing.”
Pharmaceutical and Nutraceutical Potential
The extreme conditions of the mesopelagic zone have driven the evolution of unique microbial communities, offering promising avenues for pharmaceutical and nutraceutical advances.
During the study, researchers screened 700 microbial extracts for antimicrobial properties and discovered bacteria capable of producing omega-3 fatty acids, which are valuable for aquaculture and human health. However, researchers caution that further evaluation is needed to determine the commercial viability of these resources.
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Protecting the Ecosystem
The research highlights the ecological risks of overfishing mesopelagic species. These organisms play a pivotal role in marine food webs, supporting predators such as tuna, sharks, and marine mammals. Disrupting this delicate balance could have cascading effects on the ocean’s ecosystem.
“The nocturnal migrations of mesopelagic organisms represent the largest daily migration by biomass on the planet,” the report states. “Capturing these species could significantly impact top predators and weaken marine food webs.”
Recommendations and Next Steps
The SUMMER project suggests that the benefits of protecting the mesopelagic zone outweigh the economic gains of exploitation. To support sustainable management, the team developed a virtual tool that simulates the impacts of mesopelagic migrations on carbon sequestration and biodiversity.
The project was funded by the European Union’s Horizon 2020 programme, with a €6.5 million budget and participation from 22 institutions across Europe.
Implications for the Future
As global fisheries face increasing pressures, the study urges governments and organisations to prioritise the protection of mesopelagic ecosystems. Reducing this resource now, researchers warn, could limit its future potential for climate regulation and medical innovation.
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