Plastic waste has reached all the world's oceans. This plastic pollution harms an estimated 100,000 sea turtles and marine mammals and 1,000,000 sea creatures each year. Larger plastics (called "macroplastics") such as plastic shopping bags can clog the digestive tracts of larger animals when consumed by them and can cause starvation through restricting the movement of food, or by filling the stomach and tricking the animal into thinking it is full. Microplastics on the other hand harm smaller marine life. For example, pelagic plastic pieces in the center of our ocean’s gyres outnumber live marine plankton, and are passed up the food chain to reach all marine life. A 1994 study of the seabed using trawl nets in the North-Western Mediterranean around the coasts of Spain, France, and Italy reported mean concentrations of debris of 1,935 items per square kilometre. Plastic debris accounted for 77%, of which 93% was plastic bags.