Continued human population growth and the associated development of coasts lead to dramatic effects on marine coastal ecosystems altering food resources and habitats for several species and resulting in novel species interactions. The Bay of the Seine, located in the eastern part of the English Channel, is one of the most anthropized sea in the world. Here, we report an observation of the European herring gulls (Larus argentatus) feeding on the nonindigenous species (NIS) Rangia cuneata in the Bay of the Seine. Observations of otter prints (Lutra lutra) and excrements were also found near the bivalves, suggesting that this species also feed on the NIS bivalve. Our study suggests that the spread of NIS in coastal marine ecosystem is expected to drive changes in the foraging behavior of top predators.