One study in 2004 estimated leatherbackturtles had only a 50 percent chance of avoiding being accidentally snared by a deep sea fishing line each year.
"There is the problem of plastic bags and balloons which have been ingested by leatherbackturtles off Cardigan Bay when mistaken for jelly fish, " said Ms Bell.
At the Gamba protected-area complex, on the coast of Gabon, patrolling rangers make daily logs of deposits of flotsam from the industrial world that has arrived on their remote Atlantic beaches at the same time as they record the comings and goings of the local leatherbackturtles.