Aquaculture & Fisheries

Deep Water & Demersal Fisheries

Deepwater may refer to ocean water in the abyssal zone, hadal zone, or other deep ocean zones. Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes. They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks. Demersal fish are frequently captured by a trawl net that drags along the ocean or lake floor. As a result, demersal fisheries tend to be less discriminate than pelagic fishing methods such as long lines or gill nets that target fish using specific bait, specialized hooks, or mesh size. Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks.In coastal waters they are found on or near the continental shelf, and in deep waters they are found on or near the continental slope or along the continental rise. They are not generally found in the deepest waters, such as abyssal depths or on the abyssal plain, but they can be found around seamounts and islands.

Demersal fish can be divided into two main types: strictly benthic fish which can rest on the sea floor, and benthopelagic fish which can float in the water column just above the sea floor. Benthic fish are denser than water, so they can rest on the sea floor. They either lie-and-wait as ambush predators, at times covering themselves with sand or otherwise camouflaging themselves, or move actively over the bottom in search for food.Benthic fish which can bury themselves include dragonets, flatfish and stingrays. Benthopelagic fish inhabit the water just above the bottom, feeding on benthos and zooplankton.Most demersal fish are benthopelagic.