FAO/FIIT Fishing Gear Type Fact-Sheet Midwater pair trawls [PTM] updated : 10-mai-2001 ISSCFG Classification : > Category : Trawl nets > Type : Midwater trawls > Subtype : Midwater pair trawls Profile General Description: A midwater pair trawl has roughly similar design as other midwater trawls. Midwater pair trawls might, however, be designed to have a more rectangular opening than ordinary midwater otter trawls. Midwater pair trawls might be rigged with two towingwarps from each vessel or alternatively with one towing warp from each vessel and a bridle arrangement. One of the advantages of pair trawling is the possibility to tow the trawl very close to the surface. Herding effect on fish by the two vessels may increase the capture efficiency in shallow waters and at the surface. Specific Handling Equipment: The net handling system is the same as on a single trawler and consists ofnet drums,trawl winches,sweep winches,gilsons, etc. Fishing Vessels using this gear: A pair trawler may be a very small undecked boat with an outboard engine, or any vessel up to 60 meters decked trawlers. It is a possibility for lower powered vessels to use larger trawls. The pair trawlers should have similar size and power (for having the same towing power on both sides of the trawls). Fishing Operations: A midwater pair trawl is towed simultaneously by two boats, thus ensuring the horizontal opening of the net. Setting and hauling of the trawl take place alternating between each vessel hauling the net. An important operational parameter is to maintain correct and steady distance between the two towing vessels.Radar measurements is commonly used for this purpose and for smaller boats a connecting line between the vessels will do the job. Features Target Species: Pelagic and demersal species Areas: all The Gear and its Environment: Deployment Area: Midwater pair trawling is carried out mainly at sea in all depth fromcoastal to offshore areas, but also in lakes. Impact on the Environment: No impact on bottom habitat and bottom structure. Impact on Aquatic Species: In most cases it is a single species fishery, bycatch rates of other species are low. Incidental catch ofdolphins and marine mammals may occur in some areas.