North Sea warming triggers surge in octopus and squid populations

Rising temperatures in the southern North Sea are fundamentally altering the marine food chain. Over the last century, water temperatures in these shallow regions have increased by approximately four degrees Celsius. This warming has removed previous biological barriers, allowing cephalopod eggs to hatch successfully in waters that were once too cold.

According to Hans Polet of the Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), the shift is driven by a combination of warmer waters and an abundant food supply of crabs, prawns, and herring. Simultaneously, the cod population—a primary natural predator of octopuses and squid—is declining because the warmer environment hinders their reproduction.

The impact is highly visible in the fishing industry. Tom Premereur, director of the Flemish Fish Auction, noted that while squid were rarely caught nine years ago, they now constitute the majority of catches. Cephalopods currently represent more than one-fifth of the total catch from Flemish marine fishing.