Thousands of diamondback terrapins drown each year in the Chesapeake Bay when they're caught in the crab pots that waterfront residents set in their creeks and marshes.
An Ohio University herpetologist wants to stop the unintentional losses.
Willem Roosenburg says he has a new kind of pot that would allow trapped turtles to breathe until they can be freed, while catching just as many crabs.
But his pot is 6 feet tall, and that makes it illegal in Maryland.
Crab pots are "probably the single factor that is most severely affecting terrapin populations throughout their range" from New England to Texas, he said.
"It's a considerable problem."
One abandoned pot Roosenburg pulled from the Patuxent River in 1990 contained 49 dead terrapins, and the fragmented remains of more.
In addition to being the University of Maryland's mascot, the terrapin is a scavenger and predator that plays an important role in the bay's ecosystem, he said.
And "though I'm not fond of saying it, there's also a commercial value to these animals."
They are still hunted to supply the key ingredient for venerable delicacies -- terrapin stew and soup.
The diamondback terrapin can grow to 9 inches in length. It is the only North American turtle that thrives in brackish water. It shares that habitat with the blue crab, and both are attracted to the bait used in crab pots.
And that's the heart of the problem.
First patented in 1928, crab pots are wire cubes, 2 feet on each side. The pots rest on the bottom. Crabs and turtles enter in search of the bait but can't get out again. The crabs breathe with gills and remain alive in the pot.
But turtles have lungs, and they need to surface for air.
In cold weather, a turtle caught in a pot may survive 24 hours, Roosenburg said. But in warm water it will drown in 45 minutes or less. "Ghost pots" abandoned or neglected will keep on killing.
Crab pots were banned in Maryland from 1941 to 1943 when studies found high terrapin mortality. Researchers then branded them "a distinctly destructive implement" in shallow water.
In 1943, the state relaxed the ban and allowed commercial crabbers to use pots, but only in the deeper, open reaches of the bay where terrapins rarely venture. The ban on all crab pots near shore remained.
In 1975, however, the Department of Natural Resources issued an emergency regulation allowing property owners to set pots in water adjoining their land for recreational crabbing. Residents today are allowed up to two pots.
Rick Morin, a biologist with the DNR's Fisheries Service, said those limits are sometimes ignored, and recreational pots aren't checked often enough to save the turtles.
"The waterman checks his traps every day. Property owners don't need to, because they're not doing it for a living. That's where the problem comes in," he said.
Terrapins fare worse in states that, unlike Maryland, allow commercial crab pots in shallow water, Roosenburg said.
Roosenburg, who grew up in Calvert County, estimates that more than 2,000 terrapins are killed annually in recreational crab pots on the bay shores.
His study, published this month in the journal Conservation Biology, suggests his new pots would save nearly all of them and catch just as many crabs.
That would help offset the losses due to habitat destruction and predation by raccoons, foxes, otters and dogs.
But state regulations say crab pots can't be taller than 2 feet, so they won't obstruct navigation in shallow waters.
Four years ago, DNR proposed requiring an airspace in recreational crab pots. But "it met considerable opposition," Roosenburg said.
At public meetings, waterfront property owners complained the tall pots would be too cumbersome. Roosenburg dismisses that argument. With a two-pot limit, the added difficulty would be minimal, he said.
Many property owners also said they never catch turtles in their pots. Roosenburg said that's possible where crab pots have already killed off the terrapins.
"If the new pots are used, we would expect to see an increase in terrapin populations, if suitable habitat remains," he said.
The new design would add $20 to the $16 cost of a standard pot.
Morin said a regulatory change making the tall pots permissible, but not mandatory, might help. But he said nothing like that is under consideration.
Roosenburg concedes that there is no scientific evidence that the terrapins are in decline in the Chesapeake or its tributaries.
But "in other parts of their range they certainly are," he said. And everywhere, crab pot mortality is the biggest threat. "There's a fairly large national concern."
Maryland has no handle on how the Chesapeake's terrapins are faring. "There are no estimates," said Morin. "It's a nice symbol of the bay." But because the terrapin has little commercial or
recreational value, money for studies is scarce. "It's one of those species that falls between the cracks."