Chesapeake Bay blue crab population at second-highest level since 1997, according to scientists

The Chesapeake Bay’s blue crab population is at its second-highest level since 1997, according to results from the 2011 Blue Crab Winter Dredge Survey. At 460 million crabs, the blue crab population is nearly double the record low of 249 million in 2007.

Additionally, the survey shows that there are 254 million adult crabs in the Bay, a figure that is above the 200 million population target for the third year in a row. This marks the first time since the early 1990s that there have been three consecutive years where the adult population was above the target.

These figures indicate that emergency crab management measures put into place in 2008 are helping the Bay’s blue crabs recover, according to the Maryland Department of Natural Resources (DNR) and the Virginia Marine Resources Commission (VMRC).

“We continue to realize the benefits of the very tough decisions we made three years ago – decisions that are bringing us closer to our ultimate goal: a self-sustaining fishery that will support our industry and recreational fisheries over the long term,” said Maryland Gov. Martin O’Malley.

“The stock’s improved status from just a few short years ago is neither a random event nor a reflection of improved environmental conditions,” said Dr. Rom Lipcius, who directs the Virginia component of the dredge survey for the Virginia Institute of Marine Science (VIMS).

The unusually high crab abundance allowed watermen to harvest more than 89 million pounds of crabs, the largest amount since 1993. In addition, recreational crabbing license sales increased by 8 percent in 2010. However, the combined commercial and recreational blue crab harvest did not exceed the target of 46 percent. This shows that a healthy crab industry can coexist with stronger regulations, according to VMRC.

Despite these positive figures, overall crab abundance declined due to this past winter’s deep freeze that killed as many as 31 percent of Maryland’s adult crabs, compared to about 11 percent in 2010. Crab reproduction – which is heavily influenced by environmental conditions – was also lower in 2011.

“It was a harsh winter and crab mortality was higher than normal. In fact, it was the worst we’ve seen since 1996,” said VMRC Commissioner Steven G. Bowman. “Thankfully, we acted when we did in 2008 to begin rebuilding the crab population, or the crab census results we see today would be grim indeed.”

“The evidence indicates we’ve succeeded in rebuilding the stock to a degree that it can withstand a perfect storm of rapid temperature drop as crabs move into their overwintering grounds in the lower end of the Chesapeake Bay, followed by a prolonged bout of cold weather,” said VMRC Fisheries Chief Jack Travelstead.

Abundance estimates for young of the year, mature female and adult male crabs are developed separately. Together, these groups of crabs will support the 2011 fishery and produce the next generation of crabs.

The annual Blue Crab Winter Dredge Survey is the primary assessment of the Bay’s blue crab population. Since 1990, Maryland DNR and VIMS have sampled for blue crabs at 1,500 sites throughout the Chesapeake from December to March. By sampling during winter – when blue crabs “hibernate” by burying themselves in the mud – scientists can develop the most accurate estimate of the Bay’s blu crab population.

For more information about the blue crab survey results, view this presentation from Maryland DNR.