In addition to being captured, small cetaceans, like dolphins or porpoises, can become entangled in the tow lines. Pilot whales and common dolphins in the Atlantic are particularly susceptible to being injured by dredging in nearshore areas. Many species of marine mammals forage on or near the sea floor and are at risk of being captured or injured in dredging gear. The risks to marine mammals from dredging are similar to the risks from bottom trawling. However, short tow times may lower the drowning incidence of captured juvenile turtles in dredges.Ĭaptured turtles may also become injured when they are dropped on the boat deck as the collection bag is emptied. Large rocks that accumulate inside the collection bag can damage the shell of captured sea turtles. However, dredging can be harmful to the prey species and habitat turtles depend on for survival.ĭredges, when towed across the sea floor, can crush turtles or capture them in the collection bag. Slower tow speeds sometimes allow animals to avoid capture or entanglement. The injury of loggerhead, Kemp's ridley, and green sea turtles is common and well-documented in dredge fisheries. Penetrating dredges use pressurized water jets to chase animals out from beneath muddy or rocky bottom substrate and into the collection bag. Scraping dredges collect animals in the top layer of seafloor sediment with rakes or teeth that scoop up the substrate. 2.5 knot tows with decreasing speed as catch accumulates.Dredge construction, tow time, and tow patterns vary depending on the area being dredged, species targeted, and the local density of that species, but common features of dredge fisheries include: A typical dredge consists of a mouth frame with an attached collection bag.

Setting up a dredge