Summer dredging killed sea turtles

The Brunswick News

October 30, 2009

By Mary Landers

A harbor dredging operation carried out despite concerns from wildlife officials killed at least six loggerhead sea turtles in September - two in Savannah and four in Brunswick.

A possible seventh turtle was killed in Savannah, but recovered remains have not yet been confirmed as being a sea turtle.

The Army Corps of Engineers dredged the entrances to both the Savannah and Brunswick harbors for a total of 15 days using most of $6.8 million in federal stimulus funds meted out for the project. For both operations, the corps employed hopper dredges, whose suction arms vacuum up silt and send it through giant rotating blades.

The corps usually avoids such summertime dredging precisely for the protection of turtles, and precautions were taken to minimize turtle deaths in these cases. A shrimp trawler sailed ahead of the dredge to clear the path of turtles, and each dredge's drag head was equipped with a cow catcher-like device meant to deflect turtles. A paid observer on board regularly checked for turtle remains.

Those measures reduced the turtle death toll to the federal limit allowed for this particular dredging, a limit the corps successfully petitioned to increase mid-project. But they weren't perfect.

"Seven loggerheads in 15 days is not a stellar performance," said Mark Dodd, a sea turtle researcher and biologist with the Georgia Department of Natural Resources.

Dodd also is concerned the data used to justify the demonstration project was faulty.

"The data suggested there were no takes in the summer, but they didn't have projects in the summer," he said. "They had beach renourishment, not dredging in the channel."

'Shocking' deaths

Before the operation began, the DNR was able to get corps officials to back off a plan to dredge from June through August, the height of the loggerhead nesting season. That lessened the chance of killing adult females, the most valuable turtles in terms of the threatened species' overall health. Genetic analysis failed to match any of the killed turtles with turtles known to have nested on Georgia beaches.

But September may be when turtles are most abundant in the area, because that's when migrating turtles are coming through, Dodd said.

The corps discontinued summertime dredging after about 40 sea turtles were killed in the summer of 1991. Maintenance dredging shifted to winter when turtles are less abundant.

Loggerheads currently are listed as threatened on the endangered species list, though a review is under way to see if the northern population, which nests from Georgia through the Carolinas, should be uplisted to endangered.

Dave Allison, senior campaign director for the non-profit conservation group Oceana, which has pushed for the uplisting, called the dredging project a "perverse" use of stimulus funds.

"The killing of sea turtles and putting them at further risk of extinction just to pump money through the system is at the very least unfortunate," he said. "I can understand the desire to keep dredge operators employed and keep money going through the stimulus. But there simply is no real justification for this kind of carnage."

Allison finds it "shocking" that the National Oceanic and Atmospheric Administration approved the loss of seven turtles for this project.

"If seven sea turtles were taken in two weeks in a number of fisheries in this country, we would be looking at closing the entire fishery," he said. "That rate of take is really unacceptable."

More research

Corps officials want a larger window for dredging because there are few hopper dredges available, making them difficult to schedule, said Linda Morrison, chief of the operations division for the Savannah district of the corps.

Pending further research, summertime dredging may go forward next year, Morrison said. The corps is funding some satellite tags to help determine where loggerheads travel and when.

"Maybe another month would be better," she said.

Turtles seem attracted to the cool mud of newly dredged trenches and so are especially vulnerable when the hopper dredge doubles back to smooth out its work, said Steve Calver, sea turtle coordinator for the Savannah district of the corps.

Future summertime dredging may instead use a drag beam - basically a large iron bar - to level out the bed. DNR and corps officials, however, are concerned the drag beam could smash turtles, so it may require a turtle deflecting device.

"If it'll help minimize turtle deaths, we're all for it," Calver said. "We really don't have an option not to dredge. There are too many jobs at stake. We have to figure out the best way to do it from a cost standpoint and an environmental standpoint."