What is the
Winter Crab Dredge Survey?
The winter crab dredge survey is the only bay-wide independent effort to estimate the number of blue crabs living in the Chesapeake. The survey produces information essential to species management, such as an estimate of the number of crabs over-wintering in the bay and the number of young crabs entering the population each year. Also calculated is the estimated number of females that could spawn within the year, which is an important indicator of future spawning potential. Finally, estimating the total number of crabs living in the bay allows us to calculate the percentage of the crab population that is removed by harvest each year.
A pilot version of the winter dredge survey was first conducted in 1988 with the cooperation of the University of Maryland Chesapeake Biological Lab (CBL). In 1989 the Virginia Institute of Marine Science (VIMS) joined the survey, and the two states continue to sample each winter from December through March.
Since 1994, the survey has been conducted according to a stratified random design through which the bay is divided into three regions or strata: Lower Bay (the mouth of the Chesapeake to Windmill Point, VA), Middle Bay (Windmill Point, VA to Cove Point, MD) and the Upper Bay/Tributaries (Cove Point to Pooles Island and all of the Bay’s tributaries). Each year, a total of 1,500 sites in waters deeper than 5 feet are randomly selected. The number of sites assigned in each region is proportional to its area.
For a complete description survey results visit http://www.dnr.state.md.us/fisheries/crab/winter_dredge.html
- Lynn Fegley, Project Manager