Fishing vessels that deploy gill nets snare and drown at least 400,000 seabirds every year, and the actual figure could be considerably higher, according to research published in the June edition of an academic journal devoted to conservation.
The study, in the journal Biological Conservation, uncovered reports of 81 species killed by gill nets, including penguins, ducks and some critically endangered birds such as the waved albatross. One of its three authors, Cleo Small, called the estimated toll a bare minimum, saying that data on seabird deaths from many areas were either nonexistent or too old to be useful.
“It’s quite startling,” said Small, who heads the global seabird program at the British conservation group BirdLife International, which sponsored the study.
Gill nets, which are small mesh nets, are used both by commercial and independent local fishermen. Anchored in the water by weights and buoys, they are designed to snare fish by their gills, but they can catch any creature that is too large to swim through the mesh.
Nearly half of the seabirds killed by gill nets were in a section of ocean stretching from the northern tip of Africa to north of Greenland and Scandinavia.
Seabird populations are declining faster than other types of birds, and gill nets have long been identified as a principal reason, the researchers said.
Reducing seabird deaths is difficult because there are few proven ways to deter them. Measures, such as setting gill nets at night and placing lights and sonar-style “pingers” on them, have shown some success. But many of the options are either too expensive or unworkable for local fishermen, who are major users of gill nets, said George Wallace, the vice president for oceans and islands at the American Bird Conservancy.
Most fishermen, nevertheless, want to reduce “bycatches” of birds if economically possible, Wallace said.
“Fishermen want to catch fish,” he said. “That’s what they can sell. They don’t want to tie up their lines with seabirds and sea turtles.”