. Cold-water Coral Reefs: out of sight - no longer out of mind. UNEP-WCMC Biodiversity Series 22. Cold-water coral reefs in Alaska contain some of the most abundant, diverse and pristine cold-water coral and sponge ecosystems. From 1990 to 2002, US federal fishery observer data indicate approximately 2 176 648 kg of coral and sponge bycatch occurred in the Aleutian Islands, equivalent to 52 per cent of all coral and sponge bycatch in Alaska (Shester and Ayers, in press]. Further damage caused by bottom trawling may come from sediment resuspension. The effect of sedimentation on corals is not s
. Cold-water Coral Reefs: out of sight - no longer out of mind. UNEP-WCMC Biodiversity Series 22. Cold-water coral reefs in Alaska contain some of the most abundant, diverse and pristine cold-water coral and sponge ecosystems. From 1990 to 2002, US federal fishery observer data indicate approximately 2 176 648 kg of coral and sponge bycatch occurred in the Aleutian Islands, equivalent to 52 per cent of all coral and sponge bycatch in Alaska (Shester and Ayers, in press]. Further damage caused by bottom trawling may come from sediment resuspension. The effect of sedimentation on corals is not simple but overall there is a negative trend between coral growth rate and sedimentation (Dodge et al., 1974; Dodge and Vaisnys, 1977; Hudson et al., 1982; Dodge and Lang, 19831. There are few published studies on the sensitivity of cold-water corals to sedimentation stress. Shelton (19801 showed that L. pertusa was able to clear graphite particles from its oral surface using ciliary currents. More recently Mortensen (20011 examined colonies of L. pertusa held in an aquarium for just over a year Coral growth was reduced in areas of the aquarium where there was highest background sedimentation. However, the results need further verification. Dredges are also mobile fishing gear that is towed behind vessels. A dredge consists of a frame made of steel with a mounted net behind. Large dredges can weigh 1 tonne and are used to catch clams, scallops and oysters. Dredges reduce the habitat complexity considerably as they take away all organisms, rocks and sediments that are in the gear's track. Bycatch of non- targeted species is high. Dredging over soft substrates stirs up sediment which can smother the communities living in the direction of the sediment-laden current flow. Bottom-set gillnets are used to catch benthic fish species such as the gadoids ( cod, pollock], flatfish, skates and rays. The nets can measure 100 m in length and often 10 to 20 nets are tied together in a lin
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Keywords: ., bhlconsortium, bookcollectionbiodiversity, bookcont, bookyear2004
