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Dieren en planten

Water en land

Mens en Milieu

Fishery techniques   Otter trawling   Fisheries by sort   Pelagic fisheries   Flatfish fisheries   
Otter trawl technique, Ecomare

Otter trawling

Otter trawls are nets which have otter boards fastened to the sides. When in motion under water, the boards pull away from each other resulting in the net opening up in a horizontal direction. Benthic fisheries as well as pelagic fisheries can apply this technique. Till 1960, this was the primarily method for Dutch fishermen especially when fishing for flatfish but also round fish (cod) and herring. Afterwards, the classical boards were displaced by the beam trawl. Modern fishing gear, such as twin or multi-rigging, which aim at reducing ship fuel, are once again fishing with otter boards.

By Texel


Boards of an otter trawler, Ecomare

If you want to see how otter fishing works, you can take a tourist trip with the shrimp fishing vessel TX10, departing from the harbor of Oudeschild.

  • Alternative for the beam trawler?
    Otter trawler, Onno Bakker

    The beam trawl fisheries with tickler chains endures a lot of criticism. These heavy chains locally plow the sea floor severely, at the cost of benthic life. Therefore, studies were performed to see whether otter trawling was a better choice seen from an environmental point of view. Otter trawling also scrapes the bottom, but the tracks are much narrower, usually less than a meter wide. Both fishery methods catch undersized fish and other benthic animals, along with the desired fish. However, beam trawlers catch much larger amounts than otter trawlers.

  • Twin rigging and multi-rigging

    Twin rigging is a modern form of otter trawling, whereby two towed nets are attached to each other. The boards are situated on the outside of the construction and heavy weights that glide over the bottom, called shoes, are placed between the nets. A small vessel can fish a large surface area with relatively little propulsion and at a low speed. Twin rigging fisheries is growing rapidly as an alternative for beam trawling. It is environmentally friendlier because it uses less fuel and disrupts the bottom less. Multi-rigging uses more than two nets attached together, such as three pairs of two nets each.
    Within the Dutch fishing fleet, twin and multi-rigging systems are growing particularly popular by the Wieringen fishermen that catch scampi. An increasing number of plaice fishermen from Urk are also switching to twinrigging.

  • Outrigger

    Before a beam trawler can be used as a twin or multi-rigger, it usually needs to be converted in order to make room for trawl winches on the back deck. That costs lots of money. For those fishery companies that cannot afford this investment yet still want to convert to a method of fishing that uses less fuel, outrigger trawling is a possible option. Two nets with otter boards are lowered down with the help of the trawler booms on either side of the boat. In 2006 and 2007, four fishermen from the Dutch town of Urk experimented with this method. A company on Texel joined the adventure in 2007.
    Fishing with the outrigger saves on around half of the fuel costs. However, the yields are different. Per liter ship's fuel, one earns more when fishing plaice and scampi with the outrigger than with a beam trawler. However, the balance is greater for the beam trawler when fishing for sole, turbot and brill. Other advantages to the outrigger is that it disrupts the surface of the sea floor by 22% less than a beam trawler and the percentage of undesirable by-catch is also significantly lower.