Scientists have found that deep sea fish remove and store more than one million tonnes of CO2 from Irish and British surface waters every year.
But researchers warn that large-scale fishing and mining in deep waters could deplete this valuable resource.
The research in the Proceedings of the Royal Society B journal was carried out by a team from the Marine Institute and the University of Southampton.
Using biochemical tracers, they pieced together diets of deep-water fish and in the process revealed their role in transferring carbon to the ocean depths.
They found that more than half of all fish living on the sea floor get energy from animals that go back to the surface, and not settling particles.
As a result, these bottom-living fish become a natural capture and storage facility - storing CO2 equivalent to €10m per year in carbon credits.
But the scientists have warned that fishing, energy extraction and mining threaten the habitat of these fish and as a result their ability to capture carbon.
The researchers say this is an important factor that must be taken into account when deciding how to exploit deep water habitats for food, energy or mineral resources.
