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 life 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 

 may be particularly acute in certain ocean areas. For example, 

 in the North Pacific Ocean, debris-related injuries and mor- 

 tality may be contributing to declines in populations of 

 North Pacific fur seals, Hawaiian monk seals, Steller 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 Commis- 

 sion's past efforts have been discussed in its previous Annual 

 Reports. This chapter provides an overview of the problem 

 and related activities undertaken by the Commission and others 

 during 1987. 



Background 



Since the early 1950s, the use of plastics and other 

 synthetic materials has developed at a rapid pace. As these 

 materials have been used for more and more purposes, there has 

 been a corresponding increase in the amount of plastic debris 

 entering the marine environment. Many of these products 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 they 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 the 



109 



