What about fish, isn't seafood sustainable?
Short answer: Mostly not. The FAO says about 35% of marine fish stocks are fished beyond sustainable limits, and bycatch, trawling and fish farms add hidden costs.
The share of overfished stocks has risen steadily for decades, and the figure excludes bycatch and seabed damage entirely.
FAO SOFIA (2022), 2019 data
The objection
“Fish are different, the ocean replenishes itself. Sustainable seafood is a thing.”
The answer
Some fisheries genuinely are well managed, and it would be wrong to pretend otherwise. By the data, they’re the exception.
The FAO’s own flagship report (SOFIA 2022) finds that about 35% of marine fish stocks are now fished beyond biologically sustainable limits, a share that has risen steadily for decades. The most authoritative fisheries body on Earth is reporting that over a third of assessed stocks are being depleted faster than they recover.
The catch figures hide the worst of it. Bycatch, the non-target animals hauled up and discarded, averages around 9 million tonnes a year, before counting the dolphins, turtles, sharks and seabirds killed in nets and on longlines. Bottom trawling flattens roughly 5 million km² of seabed annually, and Sala et al. (2021, Nature) estimate it also disturbs carbon-rich sediments, releasing CO2 on the scale of a major emitting industry.
Fish farming, the supposed fix, often leans back on the wild ocean. Carnivorous species like salmon are fed wild-caught fish ground into meal and oil, so aquaculture can add pressure rather than relieve it, while dense pens concentrate waste, antibiotics and parasites that spread to wild populations.
The fair concession: a minority of fisheries, and low-trophic farming like mussels and seaweed, are genuinely low-impact, among the least harmful animal products there are. But “seafood is sustainable” as a blanket claim collides with the FAO’s own numbers. A third of stocks overfished, with the damage invisible at the fish counter, is not a renewable larder.