On a foggy January morning, weeks after the end of crab season, a survey team with high-tech sonar gear was scanning the bottom of the Bay. They were trying to capture images of fishing phantoms.

There were no telltale buoys marking underwater crab pots anywhere in sight around Thomas Point at the mouth of Maryland’s South River. But, as Steve Giordano examined his shipboard computer monitor, it appeared likely that crab fishing had not entirely stopped.

“Those are definitely pots,” said Giordano, fisheries program manager at the National Oceanic and Atmospheric Administration’s Chesapeake Bay Office, pointing to nearly a dozen black squares being “seen” on the bottom by a sidescan sonar hanging over the edge of the boat.

“Look at all those,” he said. “There is not a single buoy around us.”

What Giordano had just seen were so-called “ghost pots”—abandoned fishing gear that litters the Bay bottom. They are a concern because ghost pots can lead to “ghost fishing” in which the abandoned gear continues to catch crabs, fish, turtles and other creatures until they fall apart—something that might take years.

The Bay Program’s 1997 Chesapeake Bay Blue Crab Fishery Management Plan identified ghost fishing as a potentially wasteful practice, yet the scope of the problem has never been examined Baywide.

Giordano’s interest was spurred last year as he and a survey crew were using new sonar gear to map bottom habitats in parts of Bay tributaries. “We could see the crab pots really easily, and we began noting that there are quite a few out there,” he said.

Last fall, Kirk Havens, assistant director of the center for coastal resources management at the Virginia Institute of Marine Science, saw the same thing. He and colleagues surveyed a 50-acre area of Sarah’s Creek and found that of 53 pots, 21 appeared to be ghost pots. They pulled two of the pots up and found a whelk, four oyster toadfish, a white perch and the remains of six blue crabs.

A subsequent survey over 2,400 acres of the lower York River identified 288 potential ghost pots out of 590 total pots—nearly half of all pots observed. “Certainly it appears to be a real problem,” Havens said.

No one knows just how big a problem it is. Scientists believe there may be tens of thousands—or more—ghost pots haunting the Bay. They could be spiriting away an unknown number of crabs in addition to those caught by the estimated half- million crab pots that may be in the water during the peak of crabbing season.

Those pots become “ghosts” when the are discarded, lost in storms or when buoy lines marking the pots become tangled in boat propellers and are cut loose. Indeed, the high number of ghost pots seen in preliminary studies were located in areas of high recreational boat traffic.

“It’s not really the watermen’s fault, they don’t want to lose those $20 pots,” Havens said. “We even have images where you can see that the pot has been dragged across the bottom by obviously getting caught in somebody’s prop.”

In the Bay region, watermen surveyed in 1990 estimated that 10–30 percent of their pots were lost each year. But some think that number could be low.

In the Gulf of Mexico, fishery managers estimate that 250,000 ghost blue crab pots are added to Gulf waters each year—or 25 percent of those used annually by commercial fishermen.

The potential impact is not trivial. A study in Louisiana estimated that ghost pots could kill 4 million to 10 million blue crabs annually in state waters, as well as many recreational species such as spotted seatrout, red drum and black drum.

In a recent experiment in Canada, where ghost fishing was simulated with traps targeting dungeness crabs, researches estimated that ghost fishing accounted for 7 percent of the total catch.

A panel of outside experts that conducted the peer review for a recently completed stock assessment on the Bay’s blue crabs said that ghost fishing was potentially an important source of crab source of mortality in the Bay. “It is strongly recommended that the extent of ghost fishing be assessed with regard to the potential losses, and how, if they are significant, they can be ameliorated,” the panel wrote.

Tom Miller, a fisheries scientist with the University of Maryland’s Center for Environmental Science who led the stock assessment effort, said the crabs killed by ghost fishing would not likely change the assessment’s conclusion that the crabs are not currently overfished. Crabs lost to ghost fishing, he said, are likely accounted for by estimates of natural—nonfishing—mortality used to estimate the population.

But, he said, the picture would change if the number of ghost pots were increasing, either because more were being lost, or they were lasting longer. “If ghost fishing becomes a major issue, the problem that brings about is that it might suggest that the natural mortality rate is changing over time, and that is where the concern would come,” Miller said.

By using sidescan sonar to examine parts of the Bay and its tidal tributaries, Giordano and Havens hope to come up with a better picture of how many abandoned pots are in the Bay. Further studies will try to determine how long abandoned pots will continue their ghost fishing—and what they are catching.

Those estimates can be hard to make, though. Just because crab pots are seen by the sonar does not necessarily mean they are in a condition that can trap anything. Last year, Giordano’s crew pulled a few ghost pots from the water. “A couple of them just fell apart when we picked them up,” he said. “But we had a couple of others that came up whole, and they were full of crab carcasses, and of all things, pumpkinseed—sunfish.”

Crab pots are large square traps covered with a wire mesh which are designed with several openings to allow crabs to enter, but not easily exit. Crab pots also typically have two small exit holes, called cull rings, which allow small crabs to escape.

The pots will fall apart over time, but no one know how long they will last in the Bay. Studies from other areas typically peg the life of a crab pot at two years, with newer, or heavy duty designs lasting even longer. Modern traps, for instance, are often designed with sacrificial zinc anodes which are designed to rust away, sparing the rest of the trap from the corrosive effects of salt water.

So part of the project calls for placing crab pots in the water to see how long it takes for them to deteriorate or be rendered useless by barnacles or other fouling organisms.

The researchers also want to determine how effectively abandoned pots catch crabs and other creatures compared with pots actively being fished. To lure crabs, fishermen bait pots with fish or crab parts. It is likely that abandoned pots are not as effective at luring crabs.

Nonetheless, even when the bait is gone, the pots can continue to catch some crabs, fish and other species which appear to be attracted to the foreign object. Unbaited traps also attract molting crabs, which seek hiding places when they shed their shells and are vulnerable to predation.

“It is structure, and structure has been shown to attract organisms,” Havens said. He has seen white perch, crabs and muskrats in unbaited traps—and that was during winter months. The impact could increase in spring and summer when biological activity picks up, he said.

A 1981 study in Maryland’s Sinepaxent Bay using 40 unbaited crab pots, caught 1,033 crabs, of which 33 percent were unable to escape and died. That study found that fewer crabs were caught in the winter months, but mortality was higher, possibly because the crabs are not able to bury themselves in sediment as temperatures drop.

Trapped fish and other creatures can make the ghost pot even more lethal because they—in effect—self-bait the trap. Their presence can attract crabs and other predators, which in turn are captured.

Ghost pots may be particularly deadly. Unlike pots actively being fished that are routinely checked so nontarget species can be released, being captured by a ghost pot could be a death sentence.

Scientists are especially concerned about their potential impact on diamondback terrapins. There’s concern about the status of the reptile, and they can be caught in pots in shallow areas near marshes.

“Given the sort of tenuous status of the diamondback terrapin, I think that is also an important issue to consider,” said Rom Lipcius, a crab researcher at VIMS. “It’s an issue with active crab pots,.”

If the studies confirm that ghost fishing is a problem, several actions can reduce its impact.

The sidescan sonar mapping precisely locates crab pots, making it possible to hire someone—possibly watermen—to collect pots in areas that have been surveyed. “If we have this base data, then we have the option of going in to remove the pots if we wish,” Giordano said.

Because the surveys are time consuming—the boats go back and forth across areas in straight lines at 50 meter intervals, and at about 4 knots per hour—it’s not practical to survey the whole Bay. But areas of concern, such as those with lots of crab pots and lots of recreational boating, could be targeted.

Other efforts could help prevent lost pots. Those could include educational initiatives aimed at ensuring that knots on buoys are tied correctly and emphasizing the importance of using buoys that are easily seen when marking pots. “Some of them are black, dark green or brown,” Giordano said. “They’re not really conducive to being seen.”

It’s also possible to use pots that have trap doors hinged with degradable materials, allowing the door to fall off if the pot is lost.

In the Pacific Northwest, a project supported by NOAA and local governments, teams of divers and scientists with research vessels retrieve derelict fishing gear such as crab pots and fishing nets from the water. A no-fault bill passed by Washington removes fishermen who report lost gear from liability and helps to focus recovery efforts. In some cases, the lost gear, including crab pots, can be recovered and returned.

“There is no one getting blamed, there is no fine,” said Holly Bamford, director of NOAA’s Marine Debris Program, which is also funding the Chesapeake Bay research. “It is everyone working together to remove these for the best interests of the northwest sound as well as the dungeness crab.”

Rough estimates indicated that derelict gear was accounting for 5–10 percent of the total annual catch of dungeness crabs in the Puget Sound area. “Once you make people aware of that, and how it potentially has an impact, that is like money in their pocket,” Bamford said.

Other states have special, off-season removal programs that encourage fishermen to look for and retrieve lost gear.

For the Chesapeake, where blue crabs face difficult problems such as loss of habitat, poor water quality and high fishing pressure, ghost fishing is a problem that may be an issue that is more manageable in the short-term, said Bamford, who is also a member of the Bay Program’s Scientific and Technical Advisory Committee.

“Here is something that, if it is an impact, we can help alleviate some of the stress on the blue crab,” she said. “It is a benefit to everybody to remove these crab pots, from the fishermen to the Bay community to the blue crabs themselves.”