Human actions like overfishing and habitat destruction, the study suggests, are the biggest factors at play. On top of that, climate change and pollution have led to rising water temperatures and higher acidity levels, which only make matters worse for the weakened system, according to WWF.
“As well as being a source of extraordinary natural beauty and wonder, healthy seas are the bedrock of a functioning global economy," Louise Heaps, Chief Advisor on Marine Policy at WWF-UK, said in a press release. "By over-exploiting fisheries, degrading coastal habitats and not addressing global warming, we are sowing the seeds of ecological and economic catastrophe."
For the average person, that means making sure your seafood is responsibly sourced and calling on your government to take action on climate change and protecting vulnerable habitats, the organization said.
You can just hold on to your "plenty of fish in the sea" jokes, because, well, you might not be able to make that joke for much longer if we keep it up.