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Biological Characteristics
Biological Characteristics section was composed using Collette and Klein-MacPhee, 2002.
Common Names: Black sea bass, Rock bass, Atlantic sea bass, Black fish, Black will
Taxonomic Note: Originally, Bigelow and Schroeder referred to black sea bass as Centropristes striatus but Briggs (1960) showed that the correct spelling is the current feminine form, Centropristis striata.
Description: Body is moderately stout with a rather high back. Flat-topped head with moderately pointed snout and a large, oblique mouth. Eyes set high on head.
Spiny and soft portions of the dorsal fin are seperately rounded, the latter higher than long. Caudal fin rounded posteriorly, distinctly three-lobed in large fish. Anal fin resembles the soft portion of the dorsal in rounded outline, both are soft and flexible. Pectoral fins are broad, round tipped and long, reaching back almost to the anal fin. Pelvic fins long, originating in front of the pectorals.
Scales are rather large; the top of the head is naked. Adult males develop a hump in front of dorsal fin.
Color: Black sea bass coloration varies widely, ranging from smoky gray to dusky brown or blue black, usually more or less mottled. Belly is only slightly paler than the sides, and the bases of the exposed parts of scales are paler than their margins, giving the appearance of being barred with longitudinal dots. Dorsal fin is marked with several series of whitish spots and bands; other fins mottled with dusky spots. Young fish 5-7 cm long, show greenish or brownish coloration with a dark side stripe passing from eye to caudal fin, also showing dark crossbars on their sides.
Physical Distinctions: Spiny and soft rayed portions of the dorsal fin are long and continuous versus that of the white perch, which have two short but separate fins. The rounded caudal and pectoral fins plus the short but high anal fin are sufficient to distinguish them from scup; their color precludes confusing them with redfishes, and the large mouth, pectoral fins and caudal outline distinguish them from tautog or cunner. They differ from other wreckfish in the presence of larger scales, smoothness of the head and gill covers, plus shape of the tail.
Size: Reaching up to 60 cm (Robbins and Ray 1986).
Habits: Black sea bass are strictly confined to saltwater, athough juveniles are common in high-salinity portions of estuaries (>14 ppt). Depth ranges from 1 m inshore to about 165 m offshore (Musick and Mercer 1977) depending on the season. During the inshore, summer months they are normally found in waters less than 36 m on hard bottom with nearby wrecks, piling or obstructions. While offshore they can be found adjacent to ledges and banks with hard rock or coral substrate (Hildebrand and Schroeder 1928).
Temperatures are tolerated from 6-29.8°C (Musick and Mercer 1977) but rarely below 11°C (Miller 1959). The minimum tolerated salinity is 7.7 ppt (Hardy 1978), but black sea bass are rarely found in waters of salinity lower than 12 ppt (Musick and Mercer 1977).
Feeding: Crustaceans, fishes, mollusks and worms compose the wide variety of foods consumed in the diet. Decapods are particularly important throughout all size categories (Bowman et. al. 2000) but anchovies and herring become the major component around 21 cm TL and account for 69% of the diet in fish of length 40 cm and larger.
Predation: Among the fishes sampled for food content by the NEFSC bottom trawl surveys, predators of black sea bass include little skate, spiny dogfish, goosefish, spotted hake, windowpane and summer flounder (Rountree 1999).
Breeding: Black sea bass are protogynous hermaphrodites, changing sex from female to male (Lavenda 1949). Sexual maturity usually occurs between ages 2-3, but may occur as early as age 1 for males (Mercer 1978). Increased ovarian activity leads to degeneration (of the ovaries) and sexual succession between the ages of 1-8 (Mercer 1978: Wenner et. al. 1986), no females found among fish over age 7. Although some fish may have always been male, the majority of adult males are sexually reversed females. Males larger than 25 cm have an adipose hump; they are bright blue at spawning especially around the hump and eyes. Females are darker and more dull in color. After spawning they become brownish and some fade to almost white in color (Lavenda 1949).
Spawning progresses seasonally (geographically) from south to north starting as early as April off the coast of NC and VA (Able et. al. 1995). Peak spawning season is in August and eggs can be found off Chesapeake Bay to the coast of Long Island in the north, predominantly on the inner half of shelf waters between 18-45 m in depth (Kendall 1972; Berrien and Sibunka 1999).
General Movements/Range: This species occurs along the Atlantic coast from Cape Canaveral, FL, to Cape Cod, MA, with occasional strays entering the Gulf of Maine. There are presently two stocks recognized which are divided at Cape Hatteras, NC (Shepherd 1998). The northern stock shows meristic and morphometric variation and migrates in response to seasonal temperature changes (Shepherd 1991), the southern stock does not appear to migrate (Mercer 1978). Since temperatures near SC rarely drop below 10°C (except in estuaries) the southern population is considered resident without a demonstratable migratory pattern. As the waters in the north cool with the season, the northern population appears to migrate offshore during October and November to the deeper (73-165 m) and warmer waters of the Chesapeake Bight (Richards and Castagna 1970; Lux and Nichy 1971). Once again they reappear with the rewarming of the water in the early weeks of May (Mercer 1978).
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