Marine - Species - Blue Crab
Abundance of Species
DNR surveys collected below average numbers of blue crab in 2012, similar to years before 2011. The population continues to fluctuate from low numbers seen during and after the long-term drought of 1998-2002. Recent drought conditions have continued to impact abundance and distribution, displacing crab further upriver. Data were derived from DNR's inshore crustacean survey and SCECAP projects.
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.