Blue Crabs

The Chesapeake Bay’s signature crustacean is the blue crab, Callinectes (“beautiful swimmer”) sapidus (“savory”). The blue crab is an aggressive, bottom-dwelling predator and one of the most recognizable species in the Bay. As both predator and prey, blue crabs are a keystone species in the Bay food web. Blue crabs are prey for fish, birds and even other blue crabs. Predatory fish like striped bass rely on juvenile blue crabs as part of their diet, and blue crab larvae are part of the planktonic community, fed on by filter feeders like oysters, menhaden, bay anchovies and juveniles of other fish species. Blue crabs are among the chief consumers of bottom-dwelling organisms, called “benthos.” They feed on thin-shelled bivalves, other crustaceans, fish, marine worms, plants, detritus and nearly anything else they can find.

Blue crabs make up the most productive commercial and recreational fisheries in the Bay. It is estimated that more than one-third of the nation’s blue crab catch comes from the Bay. Blue crabs—harvested as hard shell crabs, peeler crabs (just prior to molting) and soft shell crabs (immediately after molting)—have the highest value of any Chesapeake commercial fishery, bringing in more than $50 million per year. They also support a major recreational fishery in the Bay. Since the early 1990s, there has been a dramatic decrease in Bay-wide blue crab landings. Commercial crabbers have also increased their fishing effort, but are catching fewer crabs per amount of effort than in years past. These occurrences likely relate to recruitment overfishing, when large removals of adults from the stock result in fewer juveniles being produced.

Scientists use the annual Bay-wide winter dredge survey as their main tool to estimate how many blue crabs are living in the Bay. According to the results of the 2014 survey, 297 million blue crabs are estimated to be living in the Bay. Blue crabs are currently managed as a single species, using minimum catch size and seasonal limits on harvests to meet target levels of fishing pressure. The annual winter dredge survey determines if the blue crab stock’s target levels have been exceeded. Under this strategy, fishing pressure is set to levels that should allow for increased abundance of crabs over time.

Reduced acreage of underwater bay grasses has been linked to the decline of blue crabs. Bay grass beds provide important habitat for blue crabs by protecting juveniles, molting adults and feeding adults from predators. In addition to habitat loss, debate has grown over the effect of increased predation on the blue crab stock. Predatory fish like striped bass and Atlantic croaker—whose populations are currently very high—may rely on juvenile blue crabs as part of their diet, affecting the abundance of blue crab recruits (age 0 crabs). Proper management of the crab harvest, as well as water quality improvements and underwater bay grass restoration efforts, will help restore the Bay’s blue crab population and maintain this valuable resource into the future.