Fishing dredge

This article is about commercial fishing equipment. For scientific dredging equipment, seeMarine biology dredge.

Afishing dredge,also known as ascallop dredgeoroyster dredge,is a kind ofdredgewhich is towed along the bottom of the sea by afishing boatin order to collect a targeted edible bottom-dwelling species. The gear is used to fish forscallops,oystersand other species ofclams,crabs, andsea cucumber.The dredge is thenwinchedup into the boat and emptied. Dredges are also used in connection with the work of the naturalist inmarine biology,notably on theChallenger Expedition.

Scallop dredges used byNOAA

Construction

Oyster harvesting usingrakes(top) and sail driven dredges (bottom). From L'Encyclopédie of 1771.

The dredge is usually constructed from a heavy steel frame in the form of a scoop. The frame is covered with chain mesh which is open on the front, which is towed. The chain mesh functions as anet.

Dredges may or may not have teeth along the bottom bar of the frame. In Europe, early dredges had teeth, calledtynes,at the bottom. These teeth raked or ploughed the sand and mud, digging up buried clams. This design was improved by using spring-loaded teeth that reduced bottom snagging, and so could be used over rough ground.TheNew Bedford(USA) dredge does not have teeth.

Dredge nets have a coarse mesh in order to let organisms smaller than the target species through. The net catches the larger organisms: in the case of scallop dredging that includes the scallops' predators, such aswhelks,starfishandoctopus.

In some cases, several dredges are attached to a wheeled rigid axle in groups of three or four. A number of these dredges can be towed from a heavy spreading bar, usually one from each side of the vessel. The length of the bar and number of dredges towed depends on the power of the vessel and the room on the side deck for working the dredges. The number might be three on each side of a small 10-metre (33 ft) boat up to 20 on each side for a 30-metre (98 ft) vessel with 1500 hp.The great weight and strength of the gear can disturb the ground it is towed over, overturning rocks and dislodging and crushing organisms in its path.

Like a better mouse trap, there is still a challenge for inventors to produce a kinder and more gentle scallop dredge.

Types of dredgers

• 
  Musseldredgers
• 
  Fishing vesselequipped with abenthicdredge, leaving the port ofNieuwpoort
• 
  Oyster boats of the Truro oyster fleet. This fishery is the last in the world to work by sail alone

Dredging history

• 
  Vessels dredging for oysters, c. 1875
• 
  Oyster dredge at work, c.1875
• 
  dredge and its winch from askipjack

Dredging art

• 
  Oyster Boats North River,byJohn Henry Twachtman(1853–1902)
• 
  Oyster Sloop, Cos Cob,byChilde Hassam(c.1902)
• 
  Dredging For Oysters,byAlexander Rummler.WPAmural.
• 
  Oyster dredging, byCharles Napier Hemy(1841–1917)

See also

• Bottom trawling– Fishing method for fishing trawlers
• Gathering scallops– Common name for several shellfish, many edible
• Gathering seafood by hand– Methods for catching sea creatures, especially fishPages displaying short descriptions of redirect targets
• Marine biology dredge
• Oyster dredging boats:
  • Bugeye– Chesapeake Bay sailboat type for oyster dredging
  • Skipjack– Sailboat type used on Chesapeake Bay for oyster dredging.
• Solway Harvester– A scallop dredger

References

• National Research Council (US) (2002)Effects of Trawling and Dredging on Seafloor Habitat.Committee on Ecosystem Effects of Fishing.ISBN0-309-08340-0
• Hall-Spencer & Moore PG (2000) Scallop dredging has profound, long-term impacts on maerl beds. ICES Journal of Marine Science. 57, 1407-1415.

External links

• photo of scallop dredge
• drawing of scallop dredge
• Annual oyster dredging match at West MerseaArchived2020-11-06 at theWayback Machine