Slender Sole, Lyopsetta exilis
Slender Sole, Lyopsetta exilis. Fish caught from coastal waters off Redondo Beach, California, July 2023. Length: 19 cm (7.5 inches). Catch, photograph and identification courtesy of Zachary Fratello, Redondo Beach, California.
The Slender Sole, Lyopsetta exilis, is a flatfish that is a member of the Righteye Flounder or Pleuronectidae Family, that is also known as the Rough Sole and the Slim Sole and in Mexico as Platija Delgada and Platija Flaca. Globally, this is the only species in the Lyopsetta Genus.
The Slender Sole has an elongated slender shape, that is highly compressed body with a depth that is 24% to 28% of standard length. Dorsally they are brown with a darker caudal fin with a red tinge on the gill covers. Some fish have white markings on their sides. Their head has large eyes on the right side with a high ridge between and a large mouth that extends to mid-eyes, with the top eye slightly behind the lower eye. Their anal fin has 57 to 65 rays; their caudal fin is rounded or pointed; their dorsal fin has 72 to 78 rays and originates at the rear of the upper eye, and their pectoral fins are small and narrow. Their lateral line is straight.
The Slender Sole is a demersal species that is found over silt, mud and rock at depths between 9 m (30 feet) and 1,258 feet (4,126 m) in waters between 4.1oC (39oF and 10.8oC (51oF). They reach a maximum of 44 cm (17 inches) in length and 228 g (8 oz) in weight. They prey on benthic and pelagic invertebrates that include amphipods, copepods, euphausiids, shrimps and polychaetes. In turn they are preyed upon by a wide variety of fishes and by shorebirds, seals and sea lions. They have life spans of twenty years. The Slender Sole is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, diet, growth, habitat, longevity, movement patterns, and reproduction.
The Slender Sole is a resident of Mexican waters of the Pacific Ocean but has a limited range being found only from Isla Cedros, Baja California Sur, northward along the central and northwest coasts of the Baja Peninsula.
The Slender Sole, due to its slender body depth is not easily confused with any other species.
From a conservation perspective the Slender Sole is currently considered to be of Least Concern, with stable, widely distributed populations that are locally abundant in some areas. The Slender Sole is fished commercially at minor levels due to their small stature being caught primarily as a bycatch of demersal trawls. They have been dated to be at least 1.8 million years.