The sole are four species of flatfish in the Pleuronectidae family. Fish in this family are plaice, have both eyes on the right side of the face and can have a shelf life of more than two decades. The plaice is a demersal fish, that is, it lives at or near the bottom of the water. Two of the species are fished commercially, but there is disagreement as to whether they are overexploited.
The European plaice, Pleuronectes platessa, is fished commercially and recreationally in Europe. It is found on the shores of the Barents Sea to the Mediterranean, the North Atlantic and Greenland. The fish live on muddy bottoms, where they are buried in sediment during the day, and are found at depths of 32 to 164 feet (10 to 50 m). This species is dark green to dark brown with orange markings and a white underside, reaching up to 3 feet (1 m) in length and 15.5 pounds (7 kg) in weight.
Laying takes place in late winter and early spring. The female lays up to 500,000 45 eggs that float when fertilized. Young fish move to the bottom of the water when they are between 50 and 10 days old and mature between the ages of five and seven. The diet consists of crustaceans, bivalves and small fish.
The American sole, Hippoglossoides platessoides, is also known as sole. The fish are found in the Atlantic from southern Labrador to Rhode Island, spawning in April and May. The maximum length of the fish is 28 inches (70 cm). The fish are brown to red with scales larger than European species. The American sole is at depths of 295 to 590 feet (90 to 180 m).
Commercially caught, American sole is considered overexploited by the Northwest Atlantic Fisheries Organization. The Canadian government claims, however, that the single population is abundant. There are concerns that even species that are not fished for commercial purposes are at risk due to their bycatch.
Alaskan sole, Pleuronectes quadrituberculatus, is not generally fished commercially. These fish reach a length of 24 inches (60 cm) and are found in the northern Pacific Ocean, from the Gulf of Alaska to the Chukchi Sea to the Sea of Japan. The turtle garter, Acanthopsetaa nadeshnyi, can reach a length of 18 inches (46 cm). It is found in the North Pacific in the Okhotsk Sea and the Bering Sea.