Demersal

Demersal refers to aquatic organisms that inhabit or feed near the bottom of seas or lakes. The term contrasts with pelagic organisms that inhabit the water column away from the bottom. In marine contexts, demersal organisms typically live on or close to the seabed.

Demersal species are often associated with the continental shelf and slope, where they live on or near the seabed. They typically have camouflage, feeding strategies for benthic prey, and locomotion suited to the substrate, such as a benthic path or scavenging on the bottom.

Examples of demersal fish include cod, haddock, hake, sole, plaice, and halibut. Demersal invertebrates include many crustaceans (lobsters, certain crabs) and mollusks that live on or near the seafloor. They feed on benthic invertebrates, detritus, and small fishes, and may display seasonal movements along the bottom.

Fisheries targeting demersal species use bottom trawls, fixed nets, and longlines. These methods can disturb the seabed and cause bycatch of non-target species and habitats. Management measures include catch quotas, mesh-size restrictions, gear modifications, and protected areas to minimize impact.