Seabirds around the world are increasingly finding themselves in competition for food with the fishing industry, researchers found, as fishing vessels increase their catches of potential seabird prey.
“We’re fishing their food away,” said University of British Columbia fisheries professor Daniel Pauly, a principal investigator and founder of the university’s Sea Around Us initiative and an author on the recent paper in Current Biology. “We’re fishing the fish that contain the fat that they need to survive and grow.”
Researchers found the Sea Around Us and the French National Center for Scientific Research found that between 1970 and 2010, annual seabird food consumption decreased from 70 million tons to 57 million tons. Meanwhile, fishing vessels increased their catches of potential seabird prey from an average of 59 million tons in the 1970s and ’80s to 65 million tons per year in recent years.
“Even though there are far fewer seabirds now than there were before,” Pauly said, “the competition between humans and seabirds has not been reduced.”
Seabirds have experienced a 70 percent decline in the past seven decades, from the California Coast to the Mediterranean Sea, researchers found, making them the most threatened bird group. The declines included dramatic reductions in terns, frigatebirds and penguins.
For the paper, researchers mapped where seabirds caught their prey, what they were consuming and how much they were consuming and compared the findings to decades of global maps of fishery catches of prey species, including squid, herrings and sardines. Many of these species are being sought by the fishing industry for food, fish meal and fish oil.
“Fisheries generate severe constraints for seabird populations on a worldwide scale, and those need to be addressed urgently,” the authors wrote.
Competition with fishing vessels is only one of several threats impacting seabirds, Pauly said. The birds are also facing growing impacts from ingesting plastics adrift in the sea, climate change, invasive species and entanglement in fishing vessels’ nets and equipment.
“The natural world around us is unraveling,” Pauly said, “and it will be even more so as we demand more and more from nature and the ecosystem around us. We humans are many and the demands on the system around us are immense and they’re increasing. We cannot do that. We drag down these ecosystems and the animals within them.”
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