Marbled Grouper, Dermatolepis inermis
Marbled Grouper, Dermatolepis inermis. Fish caught from within the Gulf of Mexico off Cocodrie, Louisana, April, 2017. Length: 20 cm (7.9 inches). Catch, photograph and identification courtesy of Dominick Porcelli, Lighthouse Point, Florida.
The Marbled Grouper, Dermatolepis inermis, is a member of the Leather Bass or Dermatolepis Family, that is known in Mexico as cherna jaspeada and mero mάrmol. Globally, there are three species in the genus Dermatolepis, two of which are found in Mexican waters, one in Atlantic Ocean and one in the Pacific Ocean.
The Marbled Grouper has an ovate to oblong shaped strongly compressed body that is deepest at the origin of the dorsal fin and has a body depth that is 34% to 45% of standard length. They are yellowish-brown and covered with many small dark brown spots on the head, body and fins with many large white blotches on the sides. The juveniles are dark brown with irregular scattered white mottling on the head and body. Their head has a long snout with a protruding lower jaw with thick rubbery lips, an oblique forehead that has a steep profile, and a rounded preopercle that is finely serrated. Their anal fin has 3 spines and 8 to 10 rays; their caudal fin has a straight margin; their dorsal fin is continuous with 11 spines, of which the 3rd and 4th are the longest, and 18 or 20 rays; and, their pectoral fins are large and have 18 or 19 rays and are much longer than their pelvic fins. They have 21 to 24 gill rakers. They are covered with smooth scales.
The Marbled Grouper is a solitary secretive species that is found in deep rocky reef ledges, caves and crevices at depths up to 315 m (1,000 feet). They reach a maximum of 91 cm (3 feet 0 inches) in length and 10 kg (22 lbs) in weight. As of January 1, 2023, the International Game Fish Association world record stood at 14.1 kg (31 lbs 0 ounces) with the fish caught in coastal waters off Louisiana in August 2019. They consume small fish and invertebrates including crabs and shrimp and other benthic crustaceans. In turn they are preyed upon by sharks and larger teleost fish. These fish are protogynous hermaphrodites start life as females and then changing mid-life to males. Larger females produce more eggs than smaller females. The males maintain and defend harems of females. The Marbled Grouper 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 Marbled Grouper is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean. They are widely distributed but have patchy distribution and are exceedingly rare.
The Marbled Grouper can be confused with the Atlantic Tripletail, Lobotes surinamensis (three caudal fins), the Mutton Hamlet, Alphestes afer (eye is larger than the snout), the Nassau Grouper, Epinephelus striatus (wide dark bars on side; black spot at the base of caudal fin), and the Speckled Hind, Hyporthodus drummondhayi (covered with small pearly white spots).
From a conservation perspective the Marbled Grouper is currently considered as Data Deficient, as catch information is virtually nonexistent. They are heavily pursued by commercial and recreational fishermen when the form spawning aggregations at specific sites. Although poorly documented their populations are believed to be in significant decline attributed to excessive fishing pressure. They are viewed as an excellent human food fish. The juveniles are utilized by the aquarium trade and a nominal level.