Gillnets

Fishing with gillnets is a passive fishing method which uses panels of netting that hang vertically in the water. The mesh sizes of the nets are large enough to allow the head of the desired fish to go through, while not allowing the rest of its body to go through, subsequently catching the fish behind its gills. The fishery with gillnets is selective as smaller undersized fish can swim through the nets.

Anchored gillnets

Anchored gillnets are panels of net that have been anchored to the sea floor with floats holding the top of the net near the surface, making them stand up vertically in the water column. By deploying the net at specific locations and depths, different species can be targeted. By adding or subtracting weights and floats to the net, the depth in which the net is situated can be altered. Gillnets can be several kilometres long and have a low impact on the sea floor.

Driftnets

Driftnets are gillnets which are not anchored to the sea floor but drift along with the sea currents (with or without a boat). The nets follow the dominant sea current and target pelagic species such as sardines, herring, tuna, and squid. These nets can be kilometres long and are known as ‘the walls of death’, due to the fact that all sorts of non-targeted species can get entangled in the nets such as dolphins, sea turtles, sea birds, and whales. The use of driftnets has been prohibited since 2002 in European waters. While this fishing method comes with a lot of by-catch, including endangered species, it does not have any impact on the sea floor. However, as the nets damage easily, loose pieces of nets and broken off fishing gear can keep causing damage to the ecosystem (ghost fishing).

Encircling gillnets

Encircling gillnets are gillnets which are deployed around a school of fish and are often used to catch fish that swim and feed in schools like sardines, mackerel, and horse mackerel. After the net has been deployed, fishermen hit the surface water with paddles to startle the fish into the net. This method of fishing has a low impact on the sea floor.

Trammel nets

Trammel nets consist of 3 layers of netting with a small meshed inner net and two larger meshed outer nets in which fish can get entangled. This fishing method has a low impact on the sea floor but does however have a lot of by-catch and usually many unwanted species are discarded. The nets can easily be damaged and loose pieces of net and fishing gear can keep on entangling fish and damaging the ecosystem (ghost fishing).