Report | November 11, 2024

Extending the limit on deep-sea bottom fishing in the Mediterranean to preserve vulnerable habitats


Deep-sea habitats are formed by geographical features (e.g. submarine canyons, reefs, and seamounts) that host a large variety of ecosystems that are biodiversity hotspots, and may play a key role in deep-sea ecological dynamics and carbon cycling.1,2 Many of these ecosystems act as essential fish habitats (EFHs), supporting essential life stages of a large number of commercial species, and/or are vulnerable marine ecosystems (VMEs). This is the case of forests formed by black corals Leiopathes glaberrima, which create tree-like structures that provide shelter, spawning grounds, and feeding opportunities for various species ranging from small invertebrates to large predators like the Mediterranean mora (Mora moro) and deep-sea sharks (e.g. gulper shark (Centrophorus granulosus) and velvet belly lanternshark (Etmopterus spinax)).

Like black corals, most species that form EFHs and VMEs are extremely sensitive to physical disturbance, which puts deep-sea ecosystems at high risk of damage from human activities such as bottom trawling.4 Bottom trawling is recognised as the most widespread and harmful anthropogenic activity affecting the seabed globally.5,6 In the Mediterranean Sea, one clear example of its impacts is the dramatic reduction of species such as bamboo coral (Isidella elongata), a near-endemic species that lives mostly below 500 m depth; its population decreased by 80% in the last century due to the impact of trawling activity.

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