The annual winter dredge survey, which is used to estimate blue crab numbers in the Bay, suggests that the crab population still shows no sign of rebounding from the low level of abundance that has marked most of the last decade.
The total number of crabs estimated to be overwintering in the Chesapeake Bay in 2007 was similar to the abundance observed in 2006, but abundance in 2007 remained below the 17-year survey average.
The abundance of young-of-the-year crabs—those less than 2 inches across the carapace—declined significantly in 2007, and is among the lowest levels observed since the survey began in 1990.
The abundance of female crabs that will potentially spawn during 2007 remained unchanged from 2006. Female spawning abundance has remained steady since 2003, but is also below historical levels.
The Baywide survey, a cooperative effort between the Virginia Institute of Marine Science and the Maryland Department of Natural Resources Fisheries Service, uses crab dredges to sample blue crabs at 1,500 sites throughout the Chesapeake from December through March each year.
Based on the historical relationship between dredge estimates and subsequent harvests, VIMS and the DNR expect that the 2007 Bay harvest will be comparable to the 2006 harvest, which preliminary estimates put at 51.8 million pounds. Scientists added that the low abundance of juvenile crabs may lead to decreased harvests during the 2007 fall crabbing season.
By sampling during the winter, when blue crabs are buried in the mud and stationary, scientists can estimate with good precision 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.
A more complete report on the blue crab stock, which combines the winter dredge survey with other survey information from around the Bay, will be released by the Chesapeake Bay Stock Assessment Committee in late spring or early summer.