Plastic waste is an important issue for marine conservation. Globally, a greater mass of human waste goes into the ocean than the mass of fish we take out and much of the waste is plastics. And, because plastics breakdown very slowly in the environment they can accumulate in the ocean forming garbage patches.
Many animals eat or are entangled by plastic debris, which effects animals from very large things like whales to microscopic crustaceans. Photographs of the plastic filled skeletons of albatross chicks on Midway Atoll have placed seabirds among the most recognised victims of plastic pollution. Jennifer Lavers has an interesting article on The Conversation about the problem of plastic pollution for the flesh-footed shearwater and the failure of the Australian Government to place the it on the threatened species list despite significant population declines.