CHAPTER VI 



IMPACTS OF MARINE DEBRIS 



The tendency of marine mammals, sea birds, turtles, 

 fish, and invertebrates to become entangled in net fragments, 

 packing bands, and other synthetic materials lost and discarded 

 at sea has been recognized for many years. More recently, 

 problems caused by ingestion of plastic bags and other plastic 

 materials by marine animals and the fouling of beaches and 

 shorelines by all types of flotsam also have become increasingly 

 apparent. Plastic debris represents a worldwide pollution 

 problem that is particularly acute in certain ocean areas. 

 For example, in the North Pacific Ocean, debris-related injuries 

 and mortality may be contributing to declines in populations 

 of North Pacific fur seals, Hawaiian monk seals, northern sea 

 lions, harbor seals, and a number of other marine species. 



Since the early 1980s, the Marine Mammal Commission has 

 played a major role in focusing domestic and international 

 attention on ways to better assess and reduce the extent of 

 the problem for marine mammals and other species. The 

 Commission's past efforts have been discussed in its previous 

 Annual Reports. Activities undertaken by the Commission and 

 others during 1988 are discussed below. 



Background 



Since the early 1950s, plastics have become commonly 

 used for more and more purposes. The growing presence of 

 these and other synthetic materials has led to a corresponding 

 increase in the amount of plastic debris entering the marine 

 environment. Many of the products manufactured from such 

 materials degrade very slowly. Those that float remain 

 suspended at the sea surface for extended periods of time and 

 those that sink may remain on the sea floor for years or even 

 decades. As the amount of such debris increases, so too does 

 its threat to marine mammals, sea birds, turtles, fish, and 

 crustaceans. These organisms become entangled in loops and 

 openings of floating and submerged debris and they ingest 

 items, such as plastic bags and small plastic objects, because 

 these may resemble natural prey. Animals that become entangled 

 may drown, lose their ability to catch food or avoid predators, 

 or incur wounds and infections from the abrasion of attached 

 debris. Ingested plastics may block digestive tracts, damage 

 stomach linings, or reduce feeding drives. 



Until recently, the magnitude of these threats was masked 

 by the size of the ocean, the deceptively simple nature of 



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