Scientist aboard the NEAMAP SNE/MA Nearshore Trawl Survey with a dominant, male black sea bass as evidenced by the nuchal hump right at the top of its head before its dorsal fin. Photo credit: NEAMAP.
Black sea bass (Centropristis striata) inhabit Atlantic coastal waters from the Gulf of Maine to the Florida Keys, concentrating in areas from Cape Cod, Massachusetts to Cape Canaveral, Florida. Two distinct stocks of black sea bass exist along the Atlantic coast with overlapping ranges. The northern stock migrates seasonally and spawns off of New England in the late summer. A temperate reef fish, black sea bass commonly inhabit rock bottoms near pilings, wrecks, and jetties. Black sea bass rely on their large mouth and swift ocean currents to catch prey, which include fish, crabs, mussels, and razor clams. Black sea bass summer in northern inshore waters at depths of less than 120 feet and winter in southern offshore waters at depths of 240 to 540 feet.
Black sea bass are protogynous hermaphrodites, which mean they start life as a female and when they reach 9-13 inches (2 - 5 years of age) they change sex to become males. Thirty-eight percent of the females in the Mid-Atlantic demonstrate sex reversal between August and April, after most fish have spawned. Even though some fish are males when they reach sexual maturity, most produce eggs when they first mature. Following transition, a sea bass will either become a dominant male, characterized by a larger size and a bright blue nuchal hump during spawning season (see accompanying photo), or a subordinate male that has few distinguishing features.
Black sea bass are highly sought by both commercial and recreational fishermen throughout the Mid-Atlantic. Fisheries change seasonally with changes in fish distribution. Inshore and more southern commercial fisheries primarily use fish pots and handlines, and when fish move offshore in the winter, they are primarily caught in trawl fisheries targeting summer flounder, scup and Loligo squid. Recreational fisheries generally occur during the period that sea bass are inshore. Since the fishery management plan’s approval in 1997, the black sea bass commercial fishery has operated under a quota. The recreational fishery is restricted by a coastwide recreational harvest limit.
Commercial landings have been recorded since the late 1800s. Fish were primarily harvested by handlines until the early1950s. From 1887 through 1948, commercial landings north of Cape Hatteras fluctuated around six million pounds. By 1952, with the emergence of the trap fishery, landings peaked at 22 million pounds. Since implementation of quotas in 1998, commercial landings ranged between 2.9 and 3.5 million pounds until 2007. Landings declined to 1.2 million pounds in 2009, then increased to 2.3 million pounds in 2013 and have since remained above 2.5 million pounds. Commercial fishery discards represent a small fraction of total fishery removals from the stock at generally less than 0.4 million pounds per year, but increased to 0.9 and 0.7 million pounds in 2014 and 2015, respectively. Otter trawls and fish pots/traps have accounted for the majority of the black sea bass landings in most states. Other important gear includes handlines and lobster pots.
Black sea bass are also an important recreational species in the Mid-Atlantic, commonly caught using squid and natural bait. In 1965, over half of the total catch of black sea bass was credited to recreational fishing. Angling pressure increased markedly in the mid-1980s. In 1998 and 1999, recreational landings decreased substantially, which may be partially attributed to an increase in minimum size limits. Landings started to increase in 2000 and averaged 4 million pounds from 2000 to 2004. Recreational landings in 2015 were estimated at 3.7 million pounds. Recreational discard losses, assuming a 15% hook and release mortality, are generally less than 0.4 million pounds per year. In 2015, estimated mortality from recreational discards was 0.8 million pounds.
The 2016 benchmark stock assessment found black sea bass not overfished nor experiencing overfishing. With improved recruitment and declining fishing mortality rates since 2007, spawning stock biomass (SSB) has steadily increased. SSB in 2015 was estimated at 48.9 million pounds, 2.3 times the SSB target of 21.3 million pounds, and fishing mortality (F) was estimated at 0.27, well below the F target of 0.36. To account for the fact that black sea bass are protogynous hermaphrodites, which change sex from female to male, the assessment defined SSB as the total of male and female mature biomass to adjust for changes in sex ratio. Recruitment at age 1 averaged 24.3 million fish from 1989 to 2015, with peaks in 2000 (1999 cohort) at 37.3 million and at 68.9 million in 2012 (2011 cohort). The large 2011 cohort, which is currently moving through the fishery, was dominant in the northern area and less so in the south. Since 2012, recruitment has been average with the 2014 cohort estimated at 24.9 million fish. The distribution of black sea bass continues to expand northward into the Gulf of Maine.
Black sea bass is managed jointly by the Atlantic States Marine Fisheries Commission and the Mid-Atlantic Fishery Management Council (Council) under Amendment 13 to the Summer Flounder, Scup and Black Sea Bass Fishery Management Plan (August 2002) and its subsequent addenda (Addenda XII-XXVII). The objectives of the FMP are to reduce fishing mortality to assure overfishing does not occur, reduce fishing mortality on immature black sea bass to increase spawning stock biomass, improve yield from the fishery, promote compatible regulations among states and between federal and state jurisdictions, promote uniform and effective enforcement, and to minimize regulations necessary to achieve the stated objectives.
The management program divides a total annual quota between the recreational fishery (51%) and the commercial fishery (49%). Recreational fishery management measures include the same combination of minimum size limits, bag limits and fishing seasons set for the entire coast. The commercial quota is divided into state-by-state quotas annually. Specific management measures for the commercial fishery are set by each state, which may include 1) minimum size limits, 2) minimum mesh requirements for trawls or 3) a moratorium on entry into the fishery and closed seasons.
Although the black sea bass fishery was declared rebuilt in 2009, the unique characteristics of the species (e.g., it is a protogynous hermaphrodite, meaning it changes its sex from female to male) contributes to uncertainty about the size of the stock. The response of this species, as well as other hermaphroditic species, to exploitation is not fully understood. Given these concerns, the Commission approved and the Council recommended a 4.12 million pound commercial quota and a 4.29 million pound recreational harvest limit for the 2017 fishing season.