Appearance and identification
Adult American plaice are right-eyed flatfish with a large mouth, rounded tail, and an almost straight lateral line along the body. The upper, eyed surface is commonly reddish-brown, while the underside is white. These features describe the adult form after its early developmental transformation.
Sources: American Plaice species profile
Range, depth, and habitat
NOAA describes a continental-shelf range from southern Labrador to Rhode Island. In U.S. waters, American plaice occur throughout the Gulf of Maine and Georges Bank and can also be found in Maine and Massachusetts bays and estuaries.
They occupy seabeds of sand, mud, or fine gravel. Adults occur in relatively deep water, with NOAA reporting depths of about 130 to 980 feet. Juveniles generally use shallower parts of that range, typically around 130 to 590 feet. An observation near shore does not by itself mean the species normally lives at the shoreline.
Sources: American Plaice species profile
Diet and feeding
Diet changes with development. Larvae mainly eat plankton in the water column. Adults primarily take animals associated with the bottom, including brittle stars, sand dollars, polychaete worms, shrimps, and bivalve mollusks.
The larval and adult diets fit the different habitats used at those stages: young drifting fish obtain food in the water, while settled flatfish feed among bottom-dwelling organisms.
Sources: American Plaice species profile
Reproduction and the changing body
American plaice spawn and fertilize eggs near the seabed. The fertilized eggs float upward and hatch near the surface. Newly hatched larvae have a more conventional fish shape, including one eye on either side of the head.
As the young fish grows, its body flattens and the left eye moves to the right side. Once metamorphosis is complete, the juvenile settles to the bottom. The adult's asymmetry is therefore a developmental change, not the appearance with which it hatches.
Sources: American Plaice species profile
Lifespan and behavior
American plaice can survive for more than 20 years. NOAA describes them as relatively sedentary. Their distribution is closely associated with suitable shelf habitat, rather than with the long river-to-ocean migrations seen in some other fishes.
Sources: American Plaice species profile
Fishery and population assessment
American plaice are managed with other species in the Northeast groundfish complex. NOAA's profile cites a 2022 stock assessment that found the assessed population rebuilt to its target level and classified it as neither overfished nor undergoing overfishing.
Those terms describe an assessed fishery stock and its fishing pressure. They should be read with the assessment year and geographic context, rather than as a permanent verdict about every population of the species.
Sources: American Plaice species profile
