A new automatic height-control system for trawl doors could improve gear stability and reduce fuel use in pelagic and midwater fisheries. The system keeps the trawl doors at a fixed distance from the seabed and automatically adjusts them during towing. Around 50 vessels in pelagic and midwater fisheries are already using the technology to remotely control trawl doors.
The system has been developed by the Danish company Thyborøn Trawldoor. It uses sensors that monitor the position of the trawl doors relative to the seabed. The data is sent to a control unit on the vessel’s bridge. The crew can set the desired clearance, and the system keeps the doors at that height even as conditions change.
Stable Gear Performance in Changing Conditions
The sensors allow the system to react to changes in water depth, seabed conditions and towing load. The control unit automatically adjusts the doors. This reduces the need for manual adjustments during fishing.
A steady door position can also make gear performance more stable and predictable.
Designed to Reduce Seabed Contact
The system is designed to keep the trawl doors clear of the seabed. This can reduce bottom disturbance and lower towing resistance.
Lower resistance may reduce fuel use. Less contact with the seabed can also reduce wear on shoes, wear bars and other door components.
Technology Tested in Commercial Fisheries
The height-control system has been developed and tested in real fishing conditions for several years. It is now in commercial use in both bottom trawling and pelagic and midwater fisheries.
Thyborøn Trawldoor offers three types of remotely controlled trawl doors. Type 32 and Type 42 are designed for pelagic and midwater fisheries, while Type 28 is used for bottom trawling.
About 50 vessels engaged in pelagic and midwater fisheries are already equipped with fully remote-controlled and Wi-Fi-operated trawl doors. One vessel is also operating bottom trawl doors fitted with a height sensor.
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