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Research Indicates Black Sea Bass Remain Genetically Diverse Despite Historic Periods of Overfishing

Jul 18, 2019

S.C. Department of Natural Resources (SCDNR) researchers for decades have collected small inner-ear bones called otoliths from various species of fish. With breakthroughs in genetic testing, those otoliths are a rich archive for research on the health of a variety of species.

The exploitation of reef fishes off the southeastern United States by commercial and recreational fishermen has increased dramatically since the early 1970s, and many populations have been depleted as a result. Studies on a variety of marine fish species have indicated a reduction in population size diminishes genetic diversity, resulting in serious negative impacts on a stock’s long-term sustainability and resilience to overfishing.

Black sea bass (Centropristis striata) among coral. Photo credit: NOAA Fisheries.

In a S.C. Sea Grant Consortium-funded project, SCDNR researchers Tanya Darden and Tim O’Donnell examined the otoliths of black sea bass, a species which has undergone substantial decline and rebound in recent years. DNA samples were used to quantify the genetic diversity of the stock through the years. A total of 659 black sea bass were genotyped from 1981 to 2014.

A black sea bass otolith looks like a small football-shaped piece of bone. Photo by FWC Fish and Wildlife Research Institute .

The study found genetic diversity remained stable over the time period despite large fluctuations in the abundance of the species off the coast of the southeastern United States. It appears that black sea bass in the South Atlantic Bight have not experienced a genetic bottleneck despite an estimated reduction of about 50 percent in biomass between 1980 and 1992 before a population recovery began in the late 2000s.

Learn more about the Consortium’s 2016-2018 research projects.