Drift Nets Used to Catch Fish

• Drift nets are used to catch fish such as tuna, sqid, or salmon, in large quantities in the ocean or the open sea for commercial purposes. The nets can range from 25 meters to 2.5 miles or longer in length. The net is a kind of a gill net but, as the name suggests, they are not fixed in any way allowing them to move with current

Description

• Drift nets are made of a light-weight plastic monofilament that is resistant to rotting. Floats are attached to one end of the net to keep it adrift, whilea rope on the other end aids in recovery and pulling in the net later.

Mechanism

• The synthetic materials used to make gill nets are not visible to the fish, which are usually captured as they do not detect the net. The fish swim through the mesh of the net and when they try to swim away become trapped by their bony gill plates. They are also captured by becoming tangled in the netting as they swim towards it.

Catch

• The size of net mesh is crucial in drift netting, as it catches fish indiscriminately. Fish that are smaller than the circumference of the mesh will swim straight through. The nets cannot be used to target specific species of fish and there is no protection for fish that were not targeted. Along with the intended species, many endangered or noncommercial sea animals, like sea turtles, sea birds, seals, sea lions, dolphins are trapped. These animals are called bycatch. Many nets are set adrift and never recovered; these nets are commonly called "ghost nets" and are dangerous to marine life. Many environmental organization strongly oppose the use of drift nets because of the dangers they pose to animals.

Relative Motion

• Relative to the water, the drift nets remains stationary. The fish either swim towards the net themselves or are moved towards it by the tidal currents. The net itself does not lie still, however, as it moves along with the current of the water. This effect is sometimes used by expert netsmen to gauge the tidal flow and set their nets adrift accordingly. The nets are most effectively used to encircle fish and, for example, catch shoals of bass or mullet.