Maryland terrapin population fighting development, predators and crab pots

Experts: 80-90 percent of habitats destroyed

Diamondback terrapins—the official reptile of Maryland—already have a lot stacked against them.

Development along the shorelines threatens the species’ nesting habitat, and predators such as raccoons attack and kill them. They’re sometimes struck and killed by motorists. A 2000 oil spill in the Patuxent River likely also had a long-term effect on the terrapin population there, scientists say.

Then there are the crab pots.

By law, recreational crabbers must install turtle excluder devices on their pots. The device is a rectangular frame made out of wire or plastic that prevents terrapins from getting into the pot and drowning, while still allowing crabs to enter it.

Crabbers can get fined for not having the devices on their pots. Fines range from $125, plus $10 for every crab pot, up to a maximum of $500. Last year, no one in Maryland was fined for non-compliance, though Maryland Department of Natural Resources police wrote two warnings.

Only a little more than a third of recreational crabbers actually use the devices, said Scott Smith, a wildlife diversity ecologist with DNR..

The agency surveyed recreational crabbers in 2012, and found only 36 percent use TEDs on their pots. That’s a little better than in 2009, when there was a 22 percent compliance rate, Smith said.

“It’s still really low,” he said.

Terrapin populations declined considerably over the last century due to commercial harvesting of the species, which was outlawed in 2007.

“We were in a crisis about 10 or 12 years ago,” said Ray Bosmans, president of the Mid-Atlantic Turtle and Tortoise Society. “I think the terrapin can make a comeback. I’m optimistic.” 


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Bosmans believes the biggest single threat to the terrapin population is development. Some of the shoreline improvements homeowners make, including riprap and bulkheads, can be detrimental to terrapins. A natural, living shoreline is better for all species, he said.

His comments were seconded by Paul Spadaro, longtime president of the Magothy River Association in Anne Arundel County. He estimates that 80 to 90 percent of the terrapins’ nesting habitats have been destroyed due to over-development. 

“If people think it’s the crab pots, they’re going down the wrong path,” he said. “That’s not the problem.”

He said terrapin sightings are uncommon.

“I’ve maybe seen one or two terrapins, if that,” Spadaro said.

Coming across a terrapin out in the Chesapeake Bay is also rare, said Blair Baltus, the president of the Baltimore County Watermen’s Association.

“I think I’ve gotten two since 1984,” Baltus said.

As a commercial crabber, he’s not required to have a TED on his pot.

“It’s much more of an issue out on the rivers,” he said.

Still, it’s hard to get a clear picture of where the species’ population stands statewide today, Smith said.

In some areas—such as the Patuxent River—it’s taken a nosedive.

Willem Roosenburg, a scientist with Ohio University’s Center for Ecology and Evolutionary Studies, has been studying Maryland’s population for 22 years. For the last 15 years, the number of adult female diamondback terrapins in the Patuxent River has declined about 75 percent, Roosenburg said.

But head east to Poplar Island on the Eastern Shore, and it’s a different story.

“The population is increasing at a very rapid rate,” Roosenburg said.

The main reason, he said, could be due to the island’s isolation. It’s not being developed as quickly as the Patuxent River watershed, and there are fewer raccoons, foxes and other predators roaming the island.

Roosenburg still encourages recreational crabbers to install TEDs on their pots.

“Without the use of these devices, the mortality rate of turtles can be very high,” he said.  

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