The Peace/Williston Fish and Wildlife Compensation Program (PWFWCP)

Cod Key (Family Gadidae)

There are about 55 living species of cod (Gadidae). Their fossil record extends back to the Paleocene (about 60 million years) and, anatomically, they possess a curious mixture of primitive and advanced traits. Over half the species lack a proper tail (the body simply tapers to a point), and the pelvic fins originate in front of the pectoral fins.

Most cods are found in the cooler seas of the Northern and Southern Hemispheres. In this primarily marine family, however, there is one true freshwater species -- the burbot (or ling), Lota lota. This circumpolar species normally spends its entire life in fresh water, although in some northern areas (e.g., the Gulf of Bothnia and the Mackenzie Delta) it also occurs in estuaries and brackish lagoons.

This fish, burbot, is characterized by having 2 dorsal rays (the first dorsal is small), a rounded tail, a single long anal fin, and a single barbell at the tip of the chin.