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A dropline is a commercial fishing device, consisting of a long fishing line set vertically down into the water, with a series of fishing hooks attached to snoods. Droplines may be set either down underwater cliffs or just in the water column. They have a weight at the bottom of the line and a float at the top. They are not usually as long as longlines and have fewer hooks. Droplines can be contrasted with trotlines. Whereas a dropline has a series of hooks suspended vertically in the water, a trotline has a series of hooks suspended horizontally in the water. == Conservation impacts == A concern for marine conservation is that droplines are able to access areas that are otherwise natural fish refuges, such as deep sea canyons and seamounts.〔Australia's Sustainable Seafood Guide: Expanded Edition, published by AMCS〕 The Australian Marine Conservation Society rates dropline fishing as having a "moderate impact" on wildlife and a "low impact" on marine habitats.〔 Droplines have the potential to interact with orcas (killer whales). There is predation by orcas on commercial longline and dropline fish catches, including around Tasmania,〔 Bering Sea and Prince William Sound areas,〔Killer Whale (''Orcinus orca'') Depredation on Longline Catches of Sablefish (''Anoplopoma fimbria'') in Alaskan Waters. July 1988. Northwest and Alaska Fisheries Center, National Marine Fisheries Service ()〕 causing significant financial loss to commercial fishers, and threat to orcas, which can become caught or entangled, exposed to ship strikes when moving or migrating, or suffer retaliation from fishers. Retaliation in response to predation on fish catches in previous decades has included shooting and harpooning of orcas.〔〔(''Orcinus orca'': a Species Complex ), Whale and Dolphin Conservation Society. Accessed: 2007-02-13〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dropline」の詳細全文を読む スポンサード リンク
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