An important new scientific assessment of the Chesapeake Bay’s blue crab stock has been released by the federal government, setting higher abundance thresholds and crab population targets that will dictate how the agency manages the fisheries in the years to come.
A new scientific assessment of the Chesapeake Bay Blue Crab population indicates significantly more work needs to be done to fully rebuild the stock to sustainable levels. According to the National Oceanic and Atmospheric Administration assessment, although the stock has increased substantially in response to three years of rebuilding efforts by Virginia, Maryland and the Potomac River Fisheries Commission, the stock was more depleted than originally believed and will take longer to rebuild than had been expected.
The assessment, which sets a new overfishing threshold as well as a new safe abundance level for female crabs, took three years to complete and represents the best available science on the stock’s reproductive capabilities, lifespan, gender and size distributions. The assessment underwent rigorous scientific scrutiny in a peer review by Dr. Julian Addison of France, Dr. Cathy Dichmont of Australia and Dr. Billy Ernst of Chile.
Until now, fishery managers used an interim target of 200 million total adult crabs in the bay as the threshold of a healthy stock and considered overfishing to occur if 53 percent of adult (age 1+) crabs were harvested in a year. Regulations were established to meet these benchmarks, which were based on 2005 bay-wide crab assessment data.
The new stock assessment sets a new healthy-species abundance level of 215 million female crabs, with overfishing occurring if 34 percent of the female crabs are harvested in a year. Put into context, this means that fishery managers have only come close to achieving this level of female abundance three times over the past 22 years, in 2010, 1993 and 1991.
These more stringent assessments of the stock’s health will allow fishery managers to set more precise female harvest limits in order to fully rebuild the stock. Virginia, Maryland and the PRFC remain committed to working together to rebuild the bay’s crab population to meet the new female population threshold and abundance target.
In September the Chesapeake Bay Stock Assessment Committee will meet to consider the new assessment, examine data from the past two years and provide management recommendations to Maryland, Virginia and the Potomac River Fisheries Commission.
The bay-wide crab harvest in 2010 was in the 90 million-pound range, confirming that a healthy harvesting industry can coexist with regulations designed to rebuild a self-sustaining, healthy blue crab population.
Through a historic collaboration in 2008, Maryland, Virginia and the Potomac River Fisheries Commission took strong, coordinated action to reduce harvest pressure on female crabs by 34 percent. At that time, scientists deemed conservation measures necessary as blue crab suffered near historic lows in spawning stock.
“Overall, crabs in the bay are doing well. Implementing recommendations developed in the stock assessment, like focusing fishing regulations on female crabs, will help even more,” said Dr. Tom Miller, University of Maryland Center for Environmental Science, lead author of the stock assessment.
The stock assessment can be viewed in its entirety at http://hjort.cbl.umces.edu/crabs/Assessment.html
source: Virginia Marine Resources Commission/Maryland Department of Natural Resources