Esbjerg company MLD is one of the pioneers of controllable trawl doors, and while this development has been focused on the pelagic sector, the company is also working on applying this technology to demersal fisheries.
MLD has been trialling a seven-square-metre pair of demersal doors onboard Norwegian trawler Molnes, and this has demonstrated that the technology works, keeping the doors consistently steady distance of five metres above the seabed.
“This was fishing for saithe, with 19 tows totalling 65 hours for these trials. The skipper said that his catch rate was the same as he would expect with his standard trawl doors, but the doors also had practically zero ground contact (99.9% off the bottom) and this has implications for fuel consumption. This is very relevant for the Scottish fleet, and we are expecting to scale down these doors to smaller sizes that are suitable for medium-sized whitefish trawlers,” MLD’s Torben Søndergaard said.
“This provides opportunities for bottom-friendly fishing that’s gentler on the gear, as well as savings in fuel consumption. Steerable doors are the future, in terms of economy and fuel consumption, and also in providing a tool that makes more sustainable fishing a real option, and ahead of governments stepping in to take steps to minimise seabed contact. The technology is there, and it works,” he said, commenting that there are now around thirty pelagic vessels using MLD doors, mostly in the North Atlantic, although US trawler Ocean Rover has been using a pair to fish for Alaska pollock this year.
“The experience we have built up now totals around 5,000 fishing days. We also have a Danish user now, which took a while. Asbjørn is now using our doors, and we keep adding new customers. The two new pelagic vessels for Faroe Islands, Finnur Friði and Høgaberg, have both ordered doors from MLD. We also have a pair on Svend C in Greenland that they are using mainly for catching their mackerel quota – and the skipper told us that after using these he would never go back to regular doors. Steerable doors are clearly what the fishing industry wants,” he said.
“In Scotland we have doors on the new Altaire, which they are looking forward to making full use of on the mackerel fishery this year when the fish are high in the water, and we supplied pair of doors to Grateful last year, which they started using in the autumn.”
The fact that the doors are adjustable during a tow allows them to be optimised for the gear and fishing conditions, although this doesn’t mean that MLD’s doors are an off-the-shelf product. There’s a process of matching each set of doors to the fishing vessel, taking into account the size, towing power and the fishing gear, and each set is adapted to fit the stern section of the trawler using them.
There are standardised components and structures, and this enables MLD to customise doors around this basic framework, which means doors can be delivered within just four weeks, and this comes with all the guidance a new user needs.
