Southern flounder

Paralichthys lethostigma, the southern flounder, is a species of large-tooth flounder native to the East Coast of the United States and the northern Gulf of Mexico. It is a popular sport fish and is the largest and most commercially valuable flounder in the western North Atlantic Ocean and Gulf of Mexico. It is a "left-eyed flounder", meaning the left side is pigmented and is the "up side".

Habitat

Adult fish breed and spend the warmer season in coastal embayments and nearshore shelf waters, where the eggs develop until they are late stage larvae, which are then pushed by currents into the estuaries where the fish settle into the sediment and grow into juveniles. The juveniles stay in the estuaries until they reach sexual maturity and leave to spawn.

The southern flounder can survive in low salinity and has even been found in freshwater habitats both as a juvenile and as an adult.

Distribution

The southern flounder is distributed along the East Coast of the United States, north to North Carolina, and along the northern Gulf of Mexico, south to Tuxpan, but is not found in far southern Florida or the Florida Keys. A single specimen was reported in 2015 in the Mediterranean Sea off Israel, a likely escapee from mariculture.

This species is listed by the IUCN as near threatened due to both commercial and recreational overfishing, and mortality from the shrimp trawl industry. This species is also affected by habitat destruction from human causes.

Behaviour

Larval and postlarval southern flounder feed on zooplankton. As a juvenile, the southern flounder's diet consists of small invertebrates, shifting to larger invertebrates and fish as the flounder reaches adult size. Southern flounder feed on the bottom of the ocean and in the water column, and are considered to be near-top predators in their benthic environment.