To keep rays from eating scallops in certain areas, the scientists put a protective ring of poles around the scallops. rays are wider than most sea creatures and wont usually swim between poles that are spaced closely together. (the rays could turn sideways and fit through, but they dont usually do this.) other animals, however, swim easily through the gaps between poles. in 2002 and 2003, at the beginning of the fall season, researchers found populations of bay scallops that were healthy and dense. but after rays migrated through, the scallops nearly disappeared in areas that were not surrounded by poles. within protected areas, only half of the scallops were gone. its not even certain that the missing ones got eaten, peterson says, since they might just have swum away. the study suggests that efforts to replace declining populations of shellfish, such as scallops and oysters, might require extra levels of protection against predators.