Dating and fish in the sea
Shellfish such as shrimps and lobsters constitute the most valuable component of the demersal trawl catch in some areas.
A lot of demersal species depend on pelagic production by feeding on vertically migrating nekton and zooplankton entering or living in the near-bottom layer.
Piscivores usually have the capacity to deal with live prey that are large compared with their own body size, hence they tend to have big gapes.
Demersal species are also contrasted with pelagic species (see relevant sections), but the distinction between them is not always clear.
Demersal species frequently occur in mid-water and pelagic species occur close to the seabed, so that ‘demersal’ species are frequently caught in ‘pelagic’ fisheries and ‘pelagic’ species in demersal fisheries.
Many demersal fisheries are now overexploited and all are in need of careful assessment and management if they are to provide a sustainable harvest.
are carnivores, customarily grouped into three categories: piscivores, benthophages, and zooplanktivores that predominantly eat fish, benthos, and zooplankton, respectively.In many areas, the production of benthic food is low or slow compared with the pelagic production, and in a range of communities, there are actually, surprisingly few entirely benthophagous fishes, that is, which feed on epi- or infauna.
Other methods include seine nets, trammel nets, gill nets, set nets, baited lines and long lines, temporary or permanent traps, and barriers.These primarily prevent the prey from escaping and help in swallowing.Benthophagous fishes also have several prey capture methods.The species caught tend to be relatively large and of high value compared with typical pelagic species.Demersal fisheries are also known as ground-fish fisheries.Demersal fisheries are also often known as groundfish fisheries, but the terms are not exact equivalents because ‘groundfish’ excludes shellfish, which can properly be considered a part of the demersal catch.