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.
According to data from the Winter Dredge Survey, an estimated 371 million blue crabs lived in the Bay in 2018. While this marks an 18 percent decrease from the previous year and a 33 percent decrease from the year before that, experts called the population healthy, resilient and sustainable. The decrease observed between 2017 and 2018 has been attributed to a drop in the number of adult blue crabs, as the number of juvenile crabs in the Bay rose 34 percent during this time.
In the Chesapeake Bay Watershed Agreement, the Chesapeake Bay Program set a population target and an overfishing threshold for adult female blue crabs. In 2018, an estimated 147 million adult female blue crabs lived in the Bay, compared with 254 million in 2017. This number is above the 70 million overfishing threshold but below the 215 million target. This summer, experts will determine whether the blue crab stock is depleted and whether overfishing is occurring.
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.