Southern Flounder, Paralichthys lethostigma
Southern Flounder, Paralichthys lethostigma. Fish caught from coastal waters off Galveston, Texas, April 2018. Length: 36 cm (14 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
Southern Flounder, Paralichthys lethostigma. Fish caught from coastal waters off Hilton Island Island, South Carolina, July 2021. Length: 38 cm (15 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.
The Southern Flounder, Paralichthys lethostigma, is a flatfish that is a member of the Sand Flounder or Paralichthyidae Family, that is also known as lenguado limpio. Globally, there are twenty-one species in the genus Paralichthys, of which six are found in Mexican waters, three in the Atlantic and three in the Pacific Ocean.
The Southern Flounder has an oval-shaped, highly compressed body with a depth that is 43% to 48% of standard length. Dorsally they are a light brown to dark brown with diffuse spots and blotches that are more prominent in the juveniles; the ventral side is white to pale yellow in color. Their head has a slightly concave profile with a pointed snout with eyes on the left side, with the top eye slightly behind the lower eye, and a large mouth that reaches the rear of the lower eye that has large canines set in a single row on each jaw. Their anal fin has 63 to 74 rays; their caudal fin is pointed in the center; their dorsal fin has 80 to 95 rays; their pectoral fins have 11 to 13 rays and are on both sides of the body with the dorsal side fin being short and rounded; and, their pelvic fins are of equal size. They have 8 to 11 gill rakers on the lower arch. Their dorsal side is covered with smooth scales. Their lateral line is prominent being strongly arched over the pectoral fin and extends into the head and branches to the upper eye and below the lower eye.
The Southern Flounder is a demersal species that is found in marine and brackish coastal environments over sandy and muddy bottoms at depths up to 42 m (138 feet). They reach a maximum of 92 cm (3 feet 0 inches) in length and 9.3 kg (20 lbs 7 oz) in weight with females being larger than males and outnumbering males by 6:1. Their juveniles feed on small invertebrates and the adults feed on small fish, crabs and shrimp. They are known to deeper waters during winter months. They have life spans of eight years. The Southern Flounder is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Southern Flounder is a resident of Mexican waters of the Atlantic Ocean but has a limited range being found only in the Gulf of Mexico from the Texas boarder to south along the coasts of Tamaulipas and Veracruz to Tuxpan.
The Southern Flounder is most likely confused with the Gulf Flounder, Paralichthys albigutta (dorsal side with three strong ocelli spots set in a triangle).
From a conservation perspective the Southern Flounder is currently considered to be Near Threatened. Their populations went into serious decline in the 1980s and 1990s. They are considered to be a quality food fish. Historically they have been a major target of commercial fishermen utilizing gill nets in estuarine waters and also pursued by recreational anglers from bridges, jetties and small boats via hook-and-line and with spears. The fishery has been overfished by the commercial fishermen removing large quantities of juvenile sexually immature fish the majority of which are the larger females. They are also caught at significant levels by shrimp trawlers with the fish having a very high mortality rate. They are currently heavily regulated in the coastal waters of the Gulf of Mexico in the United States. The Southern Flounder has also been significantly impacted by human coastal developments.