Following mating in the late summer and early fall female blue crabs begin a southern journey to the mouth of the Chesapeake Bay where higher salinity levels are ideal for their larvae. Some crabs will travel 200 km or more to reach their destination. They migrate by walking on the bottom, swimming in a water column or a combination of the two. In November or December, the female crabs seek out a place at the bottom of the Bay.

At the same time, in all parts of the Chesapeake Bay watershed, male crabs search for deep waters in rivers and the main stem of the Bay where temperatures are more stable, water will not freeze and there is enough salinity to survive. In winter, both male and female mature crabs’ metabolisms slow due to the colder temperatures as they stay buried in mud for a period of rest.

The inactivity lasts throughout the season and it is not until spring as the waters begin to warm, that the crabs will gradually become active and return once again to the shallow rivers, creeks and tidal wetlands.

While crabs may be inactive during the winter months, Maryland Department of Natural Resources fisheries biologists get to work, with the help of Virginia, on the Annual Bay-wide Blue Crab Winter Dredge Survey to assess how many blue crabs live in all parts of the Chesapeake Bay. Last year, the survey results showed that 120 million adult or reproductive-age blue crabs live in the Bay, well below the conservation target of 200 million. Scientists use this information to determine what regulations should be enacted to ensure that blue crabs will exist for many years to come.

- Tom O’Connell
 Director
Fisheries Service
Maryland Department of Natural Resources