Another is trawling, including bottom trawl. Pair trawlers are trawlers which operate together towing a single trawl. Outrigger trawlers use outriggers, or booms, to tow the trawl. Some species form a substantial component of the bycatch of commercial trawl fisheries. Sablefish are typically caught in bottom trawl, longline and pot fisheries. The coastal fishing fleet comprises polyvalent, purse seine and trawl fishing vessels. The noun "trawl" has many possibly confusing meanings in commercial fisheries. The fishermen either let-out the trawl or heave-up the trawl during fishing operations. Each side can deploy a twin trawl or a single otter trawl. This still leaves most of international waters completely without bottom trawl regulation. They are known to attack trawl catches. This selectivity is achieved by metal grids integrated into the trawl net structure. Early collections have recorded 300 to 600 individual specimens per trawl. A search of trawl net sales points to Cro Magnon Security. One could create a mine sweeper simply by replacing the trawl with a mine sweep.