BUSINESS, ENVIRONMENT, MARINE
August 2, 2012
Crabbing in Chesapeake Bay
by Tom Horton
A major national and state effort to restore Chesapeake Bay to the health it enjoyed as recently as the 1970s is in its fourth decade now, with most of North America’s greatest estuary and its tidal rivers still receiving grades of “C” and worse in yearly assessments.
But a recent and noteworthy bright spot in this, one that promises to keep getting better, is the blue crab, the Chesapeake’s largest commercial fishery. Thousands of watermen work throughout Maryland and Virginia to supply as much as a third of the nation’s blue crabs each year.
The dramatic rebound confirmed in 2010 from a crab fishery close to collapse less than a decade ago is a testament to science-based management, also to sacrifice by commercial crabbers.
Few fisheries anywhere are more complex than pursuit in the Chesapeake of Callinectes sapidus, the “Beautiful Swimmer” memorialized in William Warner’s Pulitzer prize-winning book of the same name. Nor is any creature more thoroughly embedded in the Chesapeake’s ecology.
The blue crab ranges from Atlantic salinities at bay’s mouth to freshwater dozens of miles up tidal rivers. It eats with gusto everything from worms and oysters and small fish, to human drowning victims and other bluecrabs; and it is in turn vital food for bay life as diverse as striped bass, seaducks, herons, raccoons and crab-feasting Rotarians.
It is caught hard and soft, and while mating and molting and migrating, also deep and shallow and across the bay’s nearly 200 miles from above Baltimore to Norfolk; taken by pots, scrapes, traps, nets and on baited trotlines and handlines.
Moving freely and regularly among Maryland, Virginia and a separate management zone in the Potomac River, the blue crab has long presented the supreme management challenge.
A dramatic turning point came in the spring of 2008 as the Chesapeake’s governors, Virginia’s Tim Kaine, and Maryland’s Martin O’Malley, announced they would work together to rebuild crab populations from the lowest levels in history, close to collapse some scientists felt.
The news stories keyed on the governors’ immediately slashing catches of females a draconian 34 per cent in each state’s waters, a hit big enough to qualify bay watermen for millions in federal disaster assistance for only the second time in history.
But the real news was that such an historic bi-state commitment could never have happened until more than a decade of focused science gave managers the confidence that they finally had the tools to effectively restore crab populations.
In 1999 a 29-member Bi-State Blue Crab Advisory Committee, representing scientists, environmentalists and all parts of the seafood industry, began working to set the first-ever thresholds for how many crabs must be left at the end of the harvest to sustain a healthy population.
Strange as it may seem, despite the blue crab’s importance in Chesapeake commerce and culture for more than a century, no one had ever had more than a rough estimate of how many crabs inhabited the place—around three quarters of a billion in healthier times, it would turn out.
Key to this management effort, and growing in credibility with each year, was a random-sample winter dredge survey begun in 1989. Conducted throughout Maryland and Virginia waters by scientists with watermen running the boats, the survey was designed to provide the kind of data, independent from commercial landings, that scientists need to understand populations of marine life.
“His fellow watermen initially scoffed at what he was doing,” said Roger Morris, one of the survey captains. “They’d say, ‘Why are you dredging for crabs (which bury in the bay’s bottom in winter) in places we all know you never find many?’”
But scientific sampling and catching crabs for a living are two different games, explains Glen Davis, survey manager for Maryland’s Department of Natural Resources. It’s on the margins of crab habitat, not in the heart of it, where expansions and contractions of the population are best detected; and by counting even tiny, thumbnail-sized juvenile crabs as well as adults several inches across, the survey also gives a picture of the age structure of crabs that harvest data cannot.
By 2006 there was enough confidence in the winter survey’s predictive capability for its adoption as the primary tool in setting target levels for blue crabs in the bay.
And in the spring of 2010, the survey confirmed what the two governors could only have dreamed when they stuck their political necks out two years earlier: the population had soared 60 percent to its highest levels in more than a decade—about 660 million crabs of all sizes crawling on the Chesapeake bottom.
The luck of the weather undoubtedly played a role in such a huge turnaround. In the shallow Chesapeake (average depth 22 feet), a cold winter can elevate crab mortality; and all crabs are hatched where ebb tides carry them into the Atlantic, depending on something as capricious as the prevailing winds to blow the larvae back inshore.
But there was no doubt the dramatic uptick in blue crabs also proved that the conservation measures taken by watermen worked. Also give the blue crab its due—short-lived, about three years, and extremely fecund, with females able to release millions of eggs—it can bounce back fast.
On a scale of 10, he’d put the bay’s blue crab recovery at “around an eight,” says Peyton Robertson, director of NOAA’s Chesapeake Bay office.
There’s more work to be done, he says, in rebuilding a healthier age structure in the population—the most recent survey shows a very healthy number of crabs overall, some 750 million, but nearly three quarters are juveniles, with a slight downturn in spawning age females.
There’s also the unresolved matter of what to do about thousands of latent crabbing licenses, which could come out of the woodwork as crabs increase.
Now that the crab itself is being fished on a sustainable basis, attention has been turning to the state of the crabbers—how can they operate more efficiently and profitably?
Maryland watermen are in the 16th month of developing with the state an innovative program where the DNR would establish overall harvest goals each year, but watermen could largely control how and when they caught crabs.
“The idea is to maximize quality and crabbers’ incomes, rather than flooding the market for low prices and catching when quality is poor,” says Bill Goldsborough, senior fisheries scientist for the Chesapeake Bay Foundation.
The watermen’s first pilot project is to guarantee more reliable catch reporting, so the state can allow watermen to fish to the maximum of the year’s quota. Right now seasons may be cut off needlessly early, in effect leaving crabs and profits “on the table,” says Larry Simns, longtime head of the Maryland Watermen’s Association. Virginia has recently expressed interest in what Maryland is doing, Simns says.
“It’s what we’ve worked so long for...a deliberate, science-based management that has slowly evolved to where the old politics of fishing has much less influence,” says Ann Swanson, director of the legislative Chesapeake Bay Commission.
Swanson and the commission almost singlehandedly kept the focus on developing management science during the early 2000s, when state governments decided it was too controversial.
A final element of sustainability,
Tom Horton is a writer and outdoorsman living in Salisbury, MD.
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