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What are Drift Nets?

Ken Black
Ken Black

Drift nets are a type of net sometimes used in commercial fishing that have weights at the bottom of the net and floats at the top. These nets work by ensnaring fish by their gills, and are often referred to as gill nets. Though the technique is effective for catching large amounts of fish, it has been criticized for indiscriminately killing non-target fish species, and also marine mammals.

Though there are some bans on drift nets, the high seas are unregulated, and therefore they are still often used. Estimates are that as many as 20,000 miles (approximately 32,186 km) of nets are set each night in just the North Pacific Ocean. Though these nets are typically collected each day, the lines are in the water long enough to kill a variety of marine species. Mammals that get entangled in drift nets often die by suffocation because they cannot reach the surface to breathe air.

Salmon have historically been caught using drift nets.
Salmon have historically been caught using drift nets.

Typically, drift nets target a certain size of fish, which is determined by the diameter of the mesh. The smaller fish tend to swim right through the nets and the larger fish bounce off and swim away. The nets may also be set at different depths to target various species. The nets are unable to exclusively trap only certain species of fish, but simply catch all species of fish they encounter within a certain size range. Some may have commercial value and others may not. This situation can destroy entire populations of fish in some regions.

Drift nets may be used in commercial fishing to catch large amounts of fish.
Drift nets may be used in commercial fishing to catch large amounts of fish.

Drift nets may be dozens of miles or kilometers long, but concerns about the impact of the nets on marine mammal populations and sea birds caused the United Nations to impose restrictions in 1993. Then, the UN banned all nets longer than 1.5 miles (2.5 km). This has helped reduce the number of unintended fatalities by as much as 66 percent, but has not stopped it completely. Some of the marine mammals and birds killed are threatened or endangered species.

In some cases, especially during times of high seas or storms, drift nets may be lost at sea. These nets, generally made out of monofilament or other synthetic materials, do not break down easily, and therefore can become a big problem. They can drift and kill fish until their weight causes them to eventually sink. These lost nets are called ghost nets.

Though environmentalists criticize the use of the nets, and call for even further restrictions, the fishing industry says they are vital to meet the demand for seafood. Some countries and jurisdictions have gone further than the UN. For example, the European Union banned drift nets for catching tuna in 1998, though the technique can still be used for other species.

Frequently Asked Questions

What exactly are drift nets and how are they used in fishing?

Drift nets, also known as gillnets, are fishing nets that float freely in the water without being anchored to the bottom. They are designed to entangle fish by their gills, hence the name. Fishermen deploy these nets to capture target species as they migrate, but they can also inadvertently catch non-target species, leading to bycatch issues.

Why are drift nets considered harmful to marine ecosystems?

Drift nets can be extremely harmful due to their non-selective nature. They often result in high levels of bycatch, including dolphins, turtles, and seabirds. According to the World Wildlife Fund, millions of marine animals are caught by bycatch every year. This indiscriminate fishing method can disrupt food chains and lead to the decline of certain species.

Are there any regulations in place to control the use of drift nets?

Yes, there are regulations. The United Nations imposed a moratorium on large-scale drift net fishing in 1992, limiting the size of nets to 2.5 kilometers in length. However, enforcement varies by region and illegal use persists. Some countries have additional regulations or bans to protect their marine ecosystems.

How do drift nets differ from other types of fishing nets?

Drift nets differ from other fishing nets like trawls or seine nets in that they are not anchored or dragged along the sea floor. They are passive devices that capture fish that swim into them, whereas other nets actively enclose or scoop up marine life. This passive nature makes drift nets more prone to ghost fishing when lost or abandoned.

What are the alternatives to using drift nets for sustainable fishing?

Sustainable alternatives to drift nets include hook-and-line fishing, which targets specific species and reduces bycatch. Pots and traps are also selective and cause minimal habitat damage. Additionally, eco-friendly nets with escape hatches for non-target species and acoustic pingers to deter marine mammals are being developed to minimize ecological impact.

How can consumers help reduce the negative impacts of drift net fishing?

Consumers can help by purchasing seafood from sustainable sources that do not use drift nets. Look for certifications like the Marine Stewardship Council (MSC) label, which indicates responsible fishing practices. Supporting local fisheries that use sustainable methods and advocating for stricter regulations on drift net usage are also effective ways to contribute to marine conservation.

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    • Salmon have historically been caught using drift nets.
      By: Witold Krasowski
      Salmon have historically been caught using drift nets.
    • Drift nets may be used in commercial fishing to catch large amounts of fish.
      By: smudger21
      Drift nets may be used in commercial fishing to catch large amounts of fish.