Ghost nets have nothing to do with the paranormal. They are the result of a greedy fishing industry and political leaders who turn the other way to the suffering and needless deaths of many animals in our waters.
Ghost nets originally are intended to be used as drift nets. These are long gill nets that are not attached to anything. They are used in the open ocean or large lakes. Because they are nearly invisible at night this is when many are used. Released off boats, they have weighted bottoms and buoys on the top so that they hang vertically catching indiscriminately what ever is swimming around.
Drift nets work on the principal of only catching fish. The idea is that the fish swims forwards into the net, its own gills then work against it as they hold the fish in the net when it tries to back out. Smaller fish are able to swim through the holes, but even large sea mammals, who do not even have gills, such as dolphins and tortoises become stuck in the nets.
In length a drift net can be as long as a couple kilometers, but have been up to 25 kilometers long. Ideally they are retrieved, the fish removed, any animals caught and not needed, are released, and the cycle continues.
The ideal seldom happens.
Animals who need to surface, such as dolphins, to get air are killed; held underwater in the net, they suffocate. Protected species are also caught, and if they do not die before being hauled on board, they are often dead before they can be released.
Worse is that many nets become the subject of this article, Ghost Nets. Ghost nets are drift nets that got lost. In storms, or other mishaps, some drift nets are lost, and stalk the waters on their own. They float and continue to trap all forms of ocean life. The fish caught in the net act to attract predators and soon the ghost net becomes so heavy it sinks to the ocean floor where crustaceans consume the animals trapped within. At this point it returns to the surface, pulled up by the buoys... and the cycle continues.
Birds are also trapped in the nets as they are attracted by the sight of fish trying to flee their ghostly captor. Held underwater by the net, they drown.
Most of these modern nets are made from synthetics, giving them a long life of killing animals indiscriminately. They can float around in the open ocean, or large lakes, for years. As ocean currents pull the net , it may become entangled over coral reefs, endangering the life forms of the reef system.
Public awareness about drift nets (and ghost nets) has fallen dramatically since the 1980s when their use was hotly debated, and cruelty issues around them were well publicized.
In December, 1992, the United Nations General Assembly banned drift net use in international waters. The United States still permits drift nets in US waters, and additionally have over 1000 vessels using drift nets in European waters, where laws do not permit nets over 2.5 kilometers. Sadly the first Bush administration declined to ban their use in American waters, for fear of upsetting agreements with the Japanese.
What can you, the public do? One of the main things a person can do is eat less fish, particularly fish that were caught using drift nets. Buying farm raised fish, or catching your own, is a better solution. Support local fishermen who do not use drift nets. You can also lobby governments to oppose the use of drift nets in their waters.