Blue Crab Winter
Dredge Survey Shows Stable Adult Abundance
ANNAPOLIS — The Maryland
Department of Natural Resources (DNR) Fisheries Service and the Virginia
Institute of Marine Science (VIMS) today presented the results of the 2007
blue crab winter dredge survey, which indicates the total number of crabs
estimated to be overwintering in the Chesapeake Bay in 2007 remained
stable, similar to the number observed in 2006.
The abundance of female crabs that will spawn during 2007 remained
unchanged from 2006. Female spawning abundance has remained steady since
2003, but is below historic levels. The abundance of young of the year
crabs (less than two inches across the carapace) declined significantly in
2007, and is among the lowest levels observed in the survey. It is
important to note that fluctuations from year to year in the juvenile blue
crab index are unpredictable and not uncommon. As in 2006, total abundance
remained below the 17-year survey average.
“Once water temperatures warm, early season blue crab harvests should be
similar to last year, but lower numbers of young crabs could present some
problems later in the season,” said Howard King, Director of the Maryland
DNR Fisheries Service. “We also remain concerned that the low abundance of
young crabs could put the stock in greater risk, especially if we do not
see a rebound in the next one or two years. For the time being the
regulations in place will hold, and we will remain vigilant in monitoring
our populations and fishing pressure.”
Overall, the survey indicates that the blue crab population remains steady
at a low level of abundance. Based on the historical relationship between
dredge estimates and subsequent harvests, DNR and VIMS expect that the
2007 harvest for the Chesapeake Bay will be comparable to the 2006
harvest, which preliminary estimates place at 51.8 million pounds.
The Bay-wide blue crab winter dredge survey is a cooperative effort
between DNR and VIMS, and is the primary survey used to assess the
condition of the Chesapeake Bay blue crab population. Since 1990, the
survey has employed crab dredges to sample blue crabs at 1,500 sites
throughout the Chesapeake Bay from December through March. By sampling
during winter when blue crabs are buried in the mud and stationary,
scientists can develop, with good precision, estimates of the number of
crabs present in the Bay. Estimates of abundance are developed separately
for young of the year crabs, mature female crabs and adult male crabs.
Together these groups of crabs will support the 2007 fishery and produce
the next generation of crabs.
The winter dredge survey is the primary survey used to assess the
condition of the Chesapeake Bay blue crab population. During 2007, the
National Oceanic & Atmospheric Administration (NOAA) Chesapeake Bay Stock
Assessment Committee (CBSAC) will analyze the winter dredge survey as well
as supporting data from three additional surveys - the Maryland trawl,
Virginia trawl and Calvert Cliffs pot study. Based on the results of the
CBSAC analysis, the NOAA Chesapeake Bay Office will issue a 2007 Blue Crab
Advisory Report in the fall of 2007.
