Demersal Fisheries
Most demersal fish of commercial or recreational interest are coastal, confined to the upper 200 metres. Commercially important demersal food fish species include flatfish, such as flounder, sole, turbot, plaice, and halibut. Also important are cod, hake, redfish, haddock, bass, congers, sharks, rays and chimaeras.
The following table shows the world capture production of some groups of demersal species in tonnes.
| Capture production by groups of species in tonnes | ||||||||
|---|---|---|---|---|---|---|---|---|
| Group | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | |
| Cods, hakes, haddocks | 9,431,141 | 8,695,910 | 9,304,922 | 8,474,044 | 9,385,328 | 9,398,780 | 8,964,873 | |
| Flounders, halibuts, soles | 956,926 | 1,009,253 | 948,427 | 915,177 | 917,326 | 862,162 | 900,012 | |
| Other demersal fishes | 2,955,849 | 3,033,384 | 3,008,283 | 3,062,222 | 3,059,707 | 3,163,050 | 2,986,081 | |
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American plaice are usually found between 90 and 250 metres (but have been found at 3000 m). They feed on small fishes and invertebrates.
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Atlantic cod are usually found between 150 and 200 metres, they are omnivorous and feed on invertebrates and fish, including young cod.
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Grouper are ambush predators with a powerful sucking system that sucks their prey in from a distance.
Black sea bass inhabit US coasts from Maine to NE Florida and the eastern Gulf of Mexico, and are most abundant off the waters of New York. They are found in inshore waters (bays and sounds) and offshore in waters up to a depth of 130 m (425'). They spend most of their time close to the sea floor and are often congregated around bottom formations such as rocks, man-made reefs, wrecks, jetties, piers, and bridge pilings. Black sea bass are sought after recreational and commercial fish, and have been overfished.
Grouper are often found around reefs. They have stout bodies and large mouths. They are not built for long-distance or fast swimming. They can be quite large, and lengths over a meter and weights up to 100 kg are not uncommon. They swallow prey rather than biting pieces off it. They do not have many teeth on the edges of their jaws, but they have heavy crushing tooth plates inside the pharynx. They lie in wait, rather than chasing in open water. They are found in areas of hard or consolidated substrate, and use structural features such as ledges, rocks, and coral reefs ( as well as artificial reefs like wrecks and sunken barges) as their habitat. Their mouth and gills form a powerful sucking system that sucks their prey in from a distance. They also use their mouth to dig into sand to form their shelters under big rocks, jetting it out through their gills. Their gill muscles are so powerful that it is nearly impossible to pull them out of their cave if they feel attacked and extend those muscles to lock themselves in. There is some research indicating that roving coral groupers (Plectropomus pessuliferus) sometimes cooperate with giant morays in hunting.
Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey. They often live around features, such as seamounts, which have strong currents. Commercial examples are the orange roughy and Patagonian toothfish. Because these fish were once abundant, and because their robust bodies are good to eat, these fish have been commercially harvested.
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The Patagonian toothfish is a robust benthopelagic fish
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So is the orange roughy
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The blue grenadier (hoki), a deep water demersal fish, is subjected to a large sustainable fishing industry in New Zealand.
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