One April day, a fisherman named Johan Norman reeled in a female cod near the Norwegian village of Moskenes, where snow-capped mountains rise straight from the sea. He measured the fish: 82 centimetres from the tip of its snout to the tip of its tail. Then he pulled out his knife and sliced off several scales, placing them in a small envelope to deposit at the Institute of Marine Research in Bergen, Norway. The year was 1913.
Over the next century, as those scales sat in a repository, radical changes took place in the world’s oceans. The small sailing vessels of Norway and other fishing nations were replaced with industrial bottom trawlers. In 1968, the North Atlantic cod harvest started a precipitous decline, as did other stocks, including salmon, sole and lobster. Then, in the early 1980s, biologists began to report another worrying phenomenon. Fish in some areas were growing more slowly, maturing earlier and laying fewer eggs than before. Not only was this an ominous sign for the sustainability of these fisheries, but smaller fish are less valuable than larger ones because they yield smaller fillets.
Read more at Nature