The Atlantic cod is one of the best-studied marine fishes and most well known stories of marine fisheries management in the world. Reaching lengths of at least 6.5 feet (2 m) and weights of over 200 pounds (96 kg), this large, predatory species is known for its white, flaky flesh that is the base of several dishes in North America and Europe.
Physically, the Atlantic cod and its close relatives are noted for being the only group of fishes that have three distinct dorsal fins (along the back) and two distinct anal fins (along the ventral surface). Atlantic cod spend most of their time on or near the seafloor but may be observed feeding higher up in the water column at times. They eat a variety of prey, including several species of bony fishes, American lobsters, and other invertebrates. Adult Atlantic cod are only eaten by large sharks, but juveniles are eaten by a variety of medium-sized predators and are often even eaten by cannibalistic adults.
Atlantic cod reproduce through a behavior known as broadcast spawning, where females release eggs and males release sperm into the water column above the seafloor, at the same time. This method increases the likelihood that eggs will become successfully fertilized and that fertilized eggs will not be eaten by egg predators near the seafloor. Though they form large reproductive groups, researchers believe that dominant males gain exclusive (or nearly exclusive) rights to spawn with available females. The Atlantic cod is one of the most highly productive species of bony fish, and females may release hundreds of millions of eggs in their lifetimes. Very few of these survive to adulthood.
The Atlantic cod has been fished heavily for a thousand years. Northern European fishers following cod populations across the North Atlantic were the first Europeans to visit North America. For centuries, this species supported massive fisheries and drove the coastal economy of North America. Dried, salted Atlantic cod were also an important food source during the early colonization of the Caribbean Sea. This species was an important driver of New World civilization. Unfortunately, as fishing methods became more and more advanced, Atlantic cod populations decreased further and further, and in the late 1990s, the fishery collapsed. Even though individuals of this species produce an incredible number of eggs, the fishery was just too effective for the species to replace the numbers that were removed and eaten by humans. During the collapse, the fishery has been reduced dramatically (though not completely), but the species has struggled to rebound. Growth in numbers of other North Atlantic fishes and invertebrates may be partly to blame. Scientists agree that North Atlantic food webs have fundamentally changed as a result of the Atlantic cod collapse, and the species is currently considered vulnerable to extinction.