Atlantic cod collapse renamed lesser fish as cod
True cod are demersal Gadus fishes—chiefly Atlantic Gadus morhua and Pacific Gadus macrocephalus—prized for mild, flaky white flesh and liver oil rich in vitamins A, D, E, and omega-3s. Market shortages after stock crashes pushed pollock and cousins onto menus under cod-like trade names.
Linnaeus named the Atlantic species in 1758. Of the four species now left in Gadus, three carry the cod name, while the fourth is sold chiefly as Alaska or walleye pollock, with snow cod as a lesser trade label. Haddock and whiting share the same family and sometimes reach shops as cod, and unrelated Southern Hemisphere fish, including groupers and the Patagonian toothfish, took the name once Atlantic stocks shrank. Scrod means young cod or haddock cut into strips.
A true cod has three rounded dorsal fins, two anal fins, a jutting upper jaw, a chin barbel and a pale lateral line along a mottled greenish or sandy body. Atlantic cod usually weigh 5 to 12 kilograms, though fish of 100 kilograms have been recorded, and they can shift between grey-green and reddish-brown phases. Pacific cod are smaller and darker. Distinct Atlantic stocks, from the Arcto-Norwegian to Newfoundland, rarely mix, and eastern Baltic fish have adapted to breed in low-salinity water.
Northeastern fish spawn from January to April at about 200 metres in water of 4 to 6 °C, after courtship that includes fin displays and grunting males. Drifting larvae spend about ten weeks in the plankton, multiplying their weight fortyfold, before settling to eat small crabs and isopods; maturity comes at around 50 centimetres and three or four years. Adults hunt sand eels, squid, mackerel and even smaller cod, and in the Baltic they are the top predator of herring and sprat.
The cod worm, a parasitic crustacean, roots into the host's heart and main artery. Farming has stalled on unreliable larval survival, while Canada raised its Northern cod quota by 55 percent in 2026.
Source: Cod
