Marine - Species - Black Drum

Abundance of Species

Spotted Seatrout Abundance in SC 1990 - 2010

Recent catches of black drum in the SCDNR trammel net survey have been near the 10-year average. The extremely high abundance noted in 1999 was due to a strong year class (i.e. lots of new juveniles), but those small fish apparently experienced poor survival during their first winter of life.

This estimate of abundance is based on the SCDNR trammel net survey. This survey catches juvenile black drum up to ages of about two years, which includes sizes within the current slot limit of 14-27 inches. The juveniles live among oyster reefs along the marsh front. Since the trammel net survey operates in this habitat, we have reasonable estimates of juvenile black drum numbers. The adults, on the other hand, live in deeper waters outside the survey areas. They can live up to 50 years and reach more than 100 pounds. The upper slot limit ensures that these long-lived, big fish can spawn successfully.

Additional Graph Information

Graphs of abundance show relative annual abundance in South Carolina waters based on surveys conducted by the SC Department of Natural Resources.

Abundance is presented relative to the average of the 10 most recent years. Unlike graphs of the recreational and commercial fisheries catch, the abundance graphs use survey data that have been standardized to allow direct comparison among years.

The horizontal dotted lines above or below the "10 year average" represent one "standard deviation" unit, which is a measure of how variable the annual data are around the 10-year average. In general, the area between one standard deviation above the mean and one standard deviation below the average includes approximately 68% of the values. Approximately 95% percent of observations in the data set are found within two standard deviations of the average.