For most of the last two decades, the total number of blue crabs in the Chesapeake Bay has lingered below the long-term average. Because blue crabs are so important to the region's ecosystem and economy, both Maryland and Virginia monitor the blue crab population through an annual Winter Dredge Survey. The crabs that are collected at each of the survey's 1,500 sampling sites are measured, weighed, sexed and aged, and the data is used to estimate the number of young crabs entering the population, the number of female crabs old enough to spawn and the total number of harvestable crabs in the Bay.
In the Chesapeake Bay Watershed Agreement, the Chesapeake Bay Program set a population target and an overfishing threshold for adult female blue crabs. In 2019, an estimated 191 million adult female blue crabs lived in the Bay, compared with 147 million in 2018. This number is above the 70 million overfishing threshold but below the 215 million target.
Blue crabs are vulnerable to pollution, habitat loss and harvest pressure. Water quality improvements, underwater grass restoration and proper harvest management will be critical to maintaining this valuable resource.