![]() In trawl surveys, fish abundance (closed: 0–13 kg/30 min, open: 0–31 kg/30 min) and number of species (closed: 4–11, open: 1–9) varied between years but no effect of the closure was detected in either area. Supporting evidence from individual studiesĪ before-and-after, site comparison study in 1981–1998 of a fjord in the North Sea, Denmark (Hoffmann & Dolmer 2000) reported that prohibiting all towed fishing gears (mainly mussel dredges) in an area had no effect on the abundance and species richness of bottom-dwelling fish in the following 10 years, and compared to open areas. ICES Journal of Marine Science, 57, 1310–1314. (2000) Effect of closed areas on distribution of fish and epibenthos. Inside areas where dredging is prohibited, its indirect (disturbance) and direct (fishing mortality) effects on fish are removed, although fishing using other methods may still impact the fish species and populations.įor a related intervention, see ‘Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor’. They may also capture or damage small unwanted fish. Because of their heavy construction and deployment on the seabed, dredges can cause considerable disturbance, reducing water quality and damaging the seabed, and this has been blamed for decreases in catches of fish (Hoffmann & Dolmer, 2000). Towed shellfish dredges are usually constructed from a heavy metal frame covered with chain mesh and they vary in size and design depending on the target species. ![]() ![]() mussels, clams, scallops, crabs) and is undertaken globally and involves towing a dredge along the seabed. Dredging is done to harvest edible shellfish species (e.g. ![]()
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