The blue whiting is a small fish native to the waters of the northern Atlantic. A relative of the cod, the blue whiting is commonly fished as a food source and as a main component in various types of animal feeds. It is sold worldwide in fillet, smoked, or minced forms, or used for its oils.
Low in fat and high in protein, the blue whiting is popularly fished off the coasts of Northern Europe and the eastern coast of Canada. Typically found at a depth between 985 and 1,300 feet (about 300 to 400 m), these fish swim in schools away from the continents and above much deeper waters. Juveniles and newly hatched fish swim at shallower depths.
A slender fish, the blue whiting has a blue-gray back and silver belly. Feeding on plankton, tiny fish, and krill, each fish has large, sharp teeth, and the lower jaw juts out from beneath the top jaw. The tail fin is forked, and a long fin runs the length of the belly, while three separate fins run down the back. The eyes are large and set forward almost over the wide mouth.
The female is usually larger than the male, and the size of the fish varies. Most of these fish average between 9 and 12 inches (about 24 to 32 cm) long. It is not uncommon for some to reach mature lengths of 15 inches (about 40 cm), and those as large as almost 20 inches (about 50 cm) have been caught. Unlike many animals, the blue whiting is considered mature and fully grown at about three years of age, but does not begin to breed until between four to five years after that.
Once the fish reach maturity, they spawn in the cold late winter and early spring waters. Eggs are usually laid along the shallower continental shelves, and because of the predictable tides, young fish are often carried into the Norwegian Sea, where they grow to a size capable of swimming back out into the ocean waters against the current. Most fishing takes place during the breeding season, when large numbers of the fish cluster together.
The blue whiting is threatened by several hazards. In addition to being major prey for larger fish and various aquatic mammals, it is also subject to overfishing. As it is a small fish, large quantities are required in order for commercial fishing to be profitable. Although limits are generally placed on how many fish can be taken in a season, overfishing has been common.