Demersal fish

File:Continental shelf.svg

Profile illustrating the shelf, slope and rise

File:Giant grenadier.jpg

Giant grenadier, an elongate deep water demersal fish with large eyes and well-developed lateral lines

File:Jan van Kessel 004.jpg

Benthic flatfish and benthopelagic cod on a shore – Jan van Kessel senior, 1626–1679

File:Oceanic basin.svg

Cross-section of an ocean basin. Note significant vertical exaggeration.

File:Pseudotriakis microdon 1.jpg

The sluggish bathydemersal false catshark, shown here at a depth of 1,200 meters, has an enormous oil-filled liver which lets it hover off the continental slope at near-neutral buoyancy. It feeds on cephalopods, cutthroat eels, grenadiers, snake mackerel, and lanternsharks.

Demersal fish are a group of fish that live and feed on or near the bottom of seas or lakes. The term "demersal" comes from the Latin word demergere, which means to sink. Demersal fish are contrasted with pelagic fish, which live and feed away from the bottom, in the water column.

Characteristics

Demersal fish exhibit various adaptations that enable them to live and feed on or near the seabed. These adaptations include flattened bodies, which reduce resistance when moving along the seabed, and coloration that camouflages them against the seabed. Many demersal fish, such as flounder and sole, have both eyes on one side of their head, a feature that allows them to lie flat on the seabed while keeping an eye out for predators and prey.

Habitat

Demersal fish can be found in both marine and freshwater environments. In marine environments, they inhabit a range of depths, from the shallows down to the deep sea. Freshwater demersal species are typically found in lakes and rivers. The specific habitat of demersal fish can vary widely, from sandy, muddy, or rocky bottoms to the complex environments of coral reefs.

Diet

The diet of demersal fish primarily consists of benthic organisms, including invertebrates such as worms, crustaceans, and other small creatures living on or in the seabed. Some larger demersal fish are predators, feeding on other fish and larger prey.

Reproduction

Reproduction methods among demersal fish can vary. Many species lay eggs, which are either scattered over the seabed, attached to the substrate, or guarded by one or both parents. Other species give birth to live young.

Economic Importance

Demersal fish are of significant economic importance to humans. Many species, such as cod, haddock, and halibut, are commercially fished for food. Demersal fisheries can be found around the world, and these fish make up a substantial portion of the world's fish catch.

Conservation

The fishing of demersal species has led to overfishing and depletion of some stocks. Sustainable fishing practices and management are crucial to ensure the viability of demersal fish populations. Conservation efforts include the establishment of marine protected areas, quotas, and size limits to protect breeding populations.

Gallery

• Rhinogobius flumineus swim on the beds of rivers
  Rhinogobius flumineus swim on the beds of rivers
• Bluespotted ribbontail ray resting on the seafloor
  Bluespotted ribbontail ray resting on the seafloor
• Opsanus beta
  Opsanus beta
• Sebastolobus altivelis
  Sebastolobus altivelis
• New England Multispecies
  New England Multispecies
• Sebastes aurora noaa
  Sebastes aurora noaa
• The stargazer Uranoscopus sulphureus
  The stargazer Uranoscopus sulphureus

See Also

• Fisheries science
• Marine biology
• Sustainable fishing

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