May 30, 2014 — Fishery managers are moving forward with proposals to slash harvest pressure on female blue crabs by 10 percent after an annual survey found their numbers had dipped slightly below the level deemed “safe” by scientists.
But managers and watermen alike are frustrated that the iconic blue crab population — after showing signs of recovery — has slipped back to low levels seen prior to ramped-up management efforts imposed in 2008 that included an initial 33 percent reduction in fishing pressure on adult females. There is no single, clear explanation for the decline.
“I’m still somewhat at a loss for an explanation,” said Tom Miller, director of the University of Maryland Center for Environmental Science Chesapeake Biological Laboratory, and a scientist who has overseen the last three blue crab stock assessments.
“Single explanations are unlikely,” Miller added. “It is much more likely to be a multifaceted answer that involves several different mechanisms that are going on there.”
This annual blue crab winter dredge survey, in which scientists sample crabs buried in winter mud at 1,500 locations, showed that the number of adult female blue crabs fell to 69 million this winter, the lowest since 2002 and slightly below the 70 million threshold that scientists consider “safe.” Historically, the survey has provided an accurate snapshot of crab abundance and is the primary tool for assessing the health of the crab stock.
This year’s result would have once been defined as “overfishing” but scientists now describe the fishery as “depleted.” The reason is that in recent years fishing pressure on blue crabs has been in the range that should have protected the female population.
“The fishery now is managed in a way that we think should be sustainable,” Miller said. “So I don’t think the cause is fishery-related unless there is just massive unreported harvesting, and I don’t honestly think that is the case.”
The preliminary Baywide blue crab commercial harvest for last year was 37 million pounds, the lowest in two-and-a-half decades.
Nonetheless, managers say fishing is the one thing they can most immediately manage to reverse the blue crab population slide. So their immediate focus is for the three management agencies — the Virginia Marine Resources Commission, the Potomac River Fisheries Commission and the Maryland Department of Natural Resources — to enact regulations that would reduce harvest effort on females by an additional 10 percent. Managing harvest effort aims to maintain harvests at a certain level relative to the overall population, usually by regulating the numbers of days open to fishing and the amount and kind of gear used to fish.