10. Drift Nets
Drift nets are long (up to 90 km) free-floating nets supported by floats at the surface and weights below that cause the nets to hang vertically for up to 30 meters. All sorts of marine life, from fish and birds to sea mammals such as sea lions, seals, dolphins and sperm whales get caught up in these massive nets. Up to 90% of the catches are viewed as by-catch and thrown dead back into the sea, hence the term “walls of death”.
In 1987 the U.S. placed a limit of 1.5 nm (nautical miles) on net length, and in the early 1990s the European Union and UN banned nets longer than 2.5 km (1.35 NM). Mainly as a result of Japanese drift net fishing in the north Pacific in the 1980s, in 1992 the UN banned drift net fishing in the high seas (international waters). However, in the open ocean there is little or no enforcement and many countries continue to deploy massive nets.
Economics plays a big role in this slaughter. As countries become wealthier their populations demand more and better protein, in this case, from the sea. Countries expand their fishing fleets to cover the globe. This happened in the Atlantic as European countries prospered from the industrial revolution, in Japan after the 1970s, and is happening in China and other Asian countries now. China has a huge fleet that plunders the waters off its client states in West Africa. The industrial drift net industry is still mining the Mediterranean Sea of its marine bounty, although with diminishing returns. It is common for drift nets to be abandoned or lost at sea due to inclement weather. These nets, which are made of synthetic, non-biodegradable materials, are known as “ghost nets” and continue trapping and killing animals for decades or longer.
A recent study calls for a complete ban on fishing outside of nations’ exclusive economic zones (EEZ): “Only about 0.1 percent of fish live exclusively beyond the 200 km boundaries. Fishing stocks would benefit from the replenishment gained in non-fishing zones. Banning high seas fishing would especially benefit tuna, swordfish and many species of sharks, which roam widely. 
In 2014 The European Commission proposed to prohibit all types of drift nets in European waters. This proposal met with disagreement from individual countries and fishing organizations such as Britain’s National Federation of Fishermen’s Organizations, which pointed out that local, small-scale fishers using drift nets would be caught up in the ban and actually are no more harmful than fishing with other fishing techniques. It seems that the main problem, and the one that the Commission should be trying to address, is the scale of the fishery, which is increasingly industrial, corporate, and driven by short-term profit.
The Food and Agriculture Organization of the UN (FAO) has issued a “Code of Conduct” concerning fishing, but it is too often ignored. Many countries do not regulate properly boats carrying their flag. About 30% of fish caught worldwide are thought to be by illegal fisheries. 30% of pirated fish are from one country: Indonesia. However, most of the boats there are from other countries. The fish they catch can end up in the supply chain of North American supermarkets.
Recently, Associated Press has reported that thousands of fishermen in Indonesia are slaves, mostly Myanmar citizens taken by Thai syndicates. About a quarter of these slaves are locked up in the town of Benjina and forced to live and work in cruel conditions.
When you look at the problems associated with industrial fishing, such as bottom trawling, drift nets, and the capture of regulating bodies, it is easy to see that they stem from a common cause: big corporations together with corrupt governments are pursuing short-term profits at the expense of long-term sustainability. Until these operations are reined in, the plunder will continue.
 “(Scientific Reports, Feb 12/15)