Don’t Call It A Comeback (Yet): Blue Crab Recovery Is A Delicate Process
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LANHAM, Md. (CBSDC/AP) — The number of blue crabs in the Chesapeake Bay has dropped steeply from last year, according to an annual survey released in April.
Drudge samples from more than 1,000 sites across the bay found the total number fell from 765 million to 300 million. The number of juveniles fell from 581 million to 111 million.
The 2012 boom in the population — last year’s survey noted the highest reproduction rate in 24 years — wasn’t necessarily a sign of things to come, according to the Smithsonian’s Environmental Research Center on the Chesapeake. The slow population increase over the past few years may have been just a blip in two decades of almost nonstop decline.
The recovery of the iconic Maryland export is a fragile one, which isn’t helped by overfishing, natural predators and cannibalism. Scientists say the biggest threat to juvenile crabs comes from hungry adults. And in true Catch-22 fashion, when the adult population is high, the mortality rate of babies increases.
Smithsonian scientists are hoping they can start to better understand the crab’s life cycle, which could lead to more sustainable population growth. And that wouldn’t just be good for the Chesapeake’s local economy, it would be good for the entire ecosystem.
“Everything is connected so, if we lost the crabs, we would probably lose a lot of other species that are related, in the food web, to the crabs,” says Smithsonian researcher Paige Roberts.
Smithsonian marine Ecologist Tuck Hines has been tracking crabs within the bay for three decades. His team’s tactics include tagging adult crabs and enlisting watermen to report where they’re caught, releasing hatchery-bred juveniles implanted with microwire tags, and testing the ‘chemical fingerprints’ of crab shells to determine where in the Bay they came from.
This helps them determine where the crabs feed, where they molt and the details of their migration process.
While fishing regulations and understanding the day-to-day life of a crab may help the population, other things are largely out of the control of scientists and watermen.
This year Maryland and Virginia both reported a large influx of red drum fish, which are highly predatory on crabs. Virginia anglers last year caught and released 2.5 million red drum. That’s 40 times the 61,330 reported in 2011 and nearly 90 times the 28,580 reported in 2010, according to federal records. Maryland’s 2012 red drum harvest is estimated to be nearly 300,000 fish, compared to fewer than 3,000 in 2010 and 2011.
Bay grasses that provide protection for crabs have been significantly reduced in recent years, as well.
Some urge those worried about the crab population to keep things in perspective.
Jack Travelstead, commissioner of the Virginia Marine Resources Commission, released a statement after the 2013 drudge survey was published.
“It is important to keep these results in perspective: Five years ago this fishery was declared a federal disaster,” he wrote. “That is no longer the case. Overfishing is no longer occurring, a good fisheries management framework is in place, the stock is health and spawning-age females are doing well. If not for the disappointingly small reproductive year class, we would have much to celebrate.”
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