Photo by Ken Bivens, WSN

NC's blue crab numbers have been dropping for years, and the possible reasons why are many

The state's blue crab fishery has been declining for years, and no one knows if or when that will turn around as pressures on coastal habitats increase

They are an iconic sight and calling card for the North Carolina coast, popular with children to try and catch and adults to eat.

But like the state's oysters and flounder fisheries, blue crabs in the Tar Heel State have seen better days.

Crab numbers harvested in recent years have fallen precipitously, and there's no smoking gun as to why − although there are probably plenty of factors at play.

Dr. Dan Rittschof has been at the Duke University Marine Lab for more than 40 years.

"I've watched it crash, and it hasn't come back," said the marine ecologist of North Carolina's blue crab fishery. "What the cause? I would offer there are a lot of causes."

Like the seafood industry as a whole, officials say there are likely a number of factors contributing to the decline, including overfishing and habitat loss. Tighter health and safety regulations, rising costs, and overseas competition that has contributed to a dramatic decline in the onshore fishing infrastructure, like crab houses to process fishermen's catch, not to mention a shortage of labor also has played a role.

But Rittschof said while there's a lot of debate as to how much of a role one particular factor might be, there's one cause that is almost universally accepted.

"Declining water quality is one of the few things everyone can agree on," he said, ticking off runoff from inland agricultural sources and rampant development along the coast that sends streams of polluted stormwater into sensitive waters as the primary culprits. "I don't think you can overstate the impact people pressure is having on the system."

Climate change also could be adding pressures to coastal ecosystems, and to the habitats crabs and other marine life rely on. A report on South Carolina's struggling blue crab fishery, published by the S.C. Department of Natural Resources earlier this year, found blue crab population declines could be due to the state's estuaries getting warmer and saltier.

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