According to recent research, gill nets used by fishing vessels are responsible for the deaths of at least 400,000 seabirds each year.
Gill nets are small, mesh nets that get anchored in the water and then ensnare fish by their gills. They are commonly used by both small-scale and commercial fishermen. While they may be effective at catching fish, they also capture birds, turtles, seals and any other creature too large to swim through them.
The worst seabird death toll is in an area of ocean extending from northern Africa to north of Greenland. While numbers in the U.S. are much smaller, certain species of birds are especially vulnerable – particularly those that dive for fish.
Indeed, some studies suggest that gill nets in the U.S. are killing tens of thousands of marbled murrelets. In the past, these birds may have been able to spot the nets and avoid them. But modern nets – made from monofilament line – are virtually impossible for birds to see.
Recently, ecologists in Canada evaluated seabird populations in locations where salmon and cod fisheries were closed – and gill nets banned – in 1992. They confirmed that diving bird populations have since increased.
Seabird numbers are falling faster than for other birds. Despite the U.N.’s 1992 moratorium on large driftnets, smaller gill nets continue to be the main threat to their survival. California has made some progress by banning gill nets in certain shallow waters. Other tactics include setting nets at night and using lights or sonar to alert birds.
Clearly, strong action is needed – and quickly – to protect seabirds from these devastating effects.
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Web Links
Fish Nets Found to Kill Large Numbers of Birds
The incidental catch of seabirds in gill-net fisheries: A global review
http://www.sciencedirect.com/science/article/pii/S0006320713000979
Terrible toll of fishing nets on seabirds revealed
http://www.nature.com/news/terrible-toll-of-fishing-nets-on-seabirds-revealed-1.13084
Photo, taken on April 17, 2012, courtesy of Virginia Sea Grant via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.