Bay Blue Crab Population Increases Significantly

Scientists estimate that a total of 400 million blue crabs overwintered in the Bay in 2008-2009, up from 280 million in 2007-2008, according to data from the latest Bay-wide winter dredge survey conducted by the Maryland Department of Natural Resources and the Virginia Institute of Marine Science.

The overall abundance of adult crabs in 2008-2009 is estimated to be about 240 million crabs, slightly more than the interim target level of 200 million set by the Chesapeake Bay Stock Assessment Committee in early 2008. The increase in adult crab abundance is due primarily to a near doubling of adult females, coupled with a 50 percent increase in adult male abundance.

It is expected that the large number of mature female crabs conserved last year will significantly increase the chances of a strong spawn in 2009.

“The sharp increase in crab abundance was not a random event, nor was it due to improved environmental conditions. It was clearly due to the recent management actions," said Dr. Rom Lipcius, who directs the VIMS component of the dredge survey. “Now, we have to ensure that these females survive to spawn this summer, and that their offspring produce a healthy spawning stock in coming years.”

Despite the adult population increase, the abundance of young-of-the-year crabs (those less than 2 inches across the carapace) did not change measurably from last year, and remains below the 18-year survey average. These crabs will become vulnerable to fishing pressure later this year and represent the 2010 spawning potential.

Last spring, in response to scientific data that showed the Bay-wide population of blue crabs had plunged 70 percent since 1993, the governors of Maryland and Virginia agreed to work collaboratively on a Bay-wide effort to rebuild the species by reducing the harvest of the spawning stock of female blue crabs by 34 percent.

“While we are still above our target exploitation rate of 46 percent, the survey results represent an important first success in moving the Bay’s blue crab population to a healthier state,” said Maryland DNR Secretary John Griffin. “Now we must have the discipline to stay the course, so that we may ultimately achieve and maintain a sustainable fishery.”

For more on the 2008-2009 blue crab data, including graphs with historic population trends, visit DNR’s website.