APPENDIX F
Ecological Effects of Marine Debris*

GENERAL EFFECTS ON ECOSYSTEMS

Judgments concerning the broad impact of plastic debris on marine ecosystems are speculative at present. The bioaccumulation of plastics through food chains, for example, may be a problem, based on observations of secondary and tertiary ingestion of plastics by certain species: bald eagles preying on parakeet auklets with plastics in their stomachs (Day et al., 1985); Antarctic skuas preying on broad-billed prions in the South Atlantic (Bourne and Imbet, 1982); and shorteared owls in the Galapagos Islands preying on blue-footed boobies that had ingested fish containing plastic pellets (Anonymous, 1981).

There is little scientific information available on how debris may affect marine invertebrate species, plant life, or marine habitats in general, aside from observations that debris damages coral reefs, is ingested by squid (Araya, 1983; Machida, 1983), and may present a new habitat niche for encrusting marine species (Winston, 1982).

ENTANGLEMENT OF MARINE SPECIES

A major reason for the heightened concern over marine debris was the increasing number of reports that plastic was causing widespread mortality of marine species. Among the first species to be highlighted was the Northern fur seal. Studies indicated that each year as many as 50,000 of these seals were

*  

Summary prepared by the Committee on Shipborne Wastes as a supplement to Chapter 2.



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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea APPENDIX F Ecological Effects of Marine Debris* GENERAL EFFECTS ON ECOSYSTEMS Judgments concerning the broad impact of plastic debris on marine ecosystems are speculative at present. The bioaccumulation of plastics through food chains, for example, may be a problem, based on observations of secondary and tertiary ingestion of plastics by certain species: bald eagles preying on parakeet auklets with plastics in their stomachs (Day et al., 1985); Antarctic skuas preying on broad-billed prions in the South Atlantic (Bourne and Imbet, 1982); and shorteared owls in the Galapagos Islands preying on blue-footed boobies that had ingested fish containing plastic pellets (Anonymous, 1981). There is little scientific information available on how debris may affect marine invertebrate species, plant life, or marine habitats in general, aside from observations that debris damages coral reefs, is ingested by squid (Araya, 1983; Machida, 1983), and may present a new habitat niche for encrusting marine species (Winston, 1982). ENTANGLEMENT OF MARINE SPECIES A major reason for the heightened concern over marine debris was the increasing number of reports that plastic was causing widespread mortality of marine species. Among the first species to be highlighted was the Northern fur seal. Studies indicated that each year as many as 50,000 of these seals were *   Summary prepared by the Committee on Shipborne Wastes as a supplement to Chapter 2.

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea becoming entangled and dying in plastic debris, primarily fishing nets and strapping bands. Subsequent findings have shown that the increased use and subsequent disposal of plastics in the marine environment is causing widespread mortality among marine mammals, turtles, birds, and fish, either through entanglement or ingestion. However, most of this information is drawn from a few studies, and there has been no attempt to compile the data at one source, nor has there been any extensive effort to monitor trends. Entanglement in plastic debris poses a potentially serious threat to a number of marine species, at both the individual and population levels. (To date, the threat to populations has been documented only in the Northern fur seal.1) Marine mammals, sea turtles, seabirds, and fish have been found entangled in the loops and openings of fishing nets, strapping bands, and other plastic items. Once ensnared, an individual may be unable to swim or feed or may incur open wounds that become infected. There have been attempts to identify the circumstances that can lead to entanglement. In some cases, random encounters with debris are to blame. For example, an animal may not be able to see or otherwise detect plastic debris, especially fishing gear designed to be nearly transparent in water (Balazs, 1985). However, a number of biological factors appear to increase the risk of entanglement for certain species. Like natural ocean rubble such as sargassum weed and logs, floating plastics attract fish, crustaceans, and other species seeking shelter and concentrated food sources. Marine mammals, turtles, and birds also are attracted to floating debris, and they may become ensnared when attempting to feed. Predators, such as seals and sea birds, are at increased risk of becoming entangled in discarded fishing gear, which may have fish entrapped in netting. Finally, pinnipeds haul themselves out of the water to rest on natural debris, such as floating kelp mats and logs, while young seals are attracted to floating objects as playthings. If such debris includes plastics, entanglement can result. Due to their behavioral characteristics, seals and sea lions may be the most prone to entanglement. Individuals from at least 15 of the world's 32 species of seals have been observed ensnared in plastic debris; these include several species found in the United States, such as the northern fur seal (Fowler, 1985, 1988; Scordino, 1985), northern sea lion (Calkins, 1985), California sea lion, northern elephant seal, harbor seal (Stewart and Yochem, 1985, 1987), and the Hawaiian monk seal (Henderson, 1984, 1985), which is on the U.S. government's list of endangered species. 1   The Pribilof Islands of Alaska are home to a population of approximately 827,000 Northern fur seals, 71 percent of the estimated total world population of this species. Studies show that the Pribilof population is less than half that observed 40 years ago and is declining at an annual rate of 4 to 8 percent (Fowler and Merrell, 1986). Entanglement in plastic debris is thought to be contributing to the decline.

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea Most information available on pinniped interactions with debris has been compiled by the National Marine Fisheries Service (NMFS). The effects of entanglement on an individual animal may vary. Most entangled Northern fur seals have been observed with debris around their necks and shoulders. This kind of entanglement, if constricting, may directly impair swimming or feeding. Entangling debris also increases drag during swimming. Consequently, an entangled seal must use more energy to swim than it normally would and therefore must consume more food to compensate; unfortunately, drag inhibits the high-speed swimming required for pursuit of prey and therefore may lead to starvation of the animal. In other cases, abrasion from entangling debris may cause wounds that are susceptible to infection. Entanglement of breeding animals also can adversely affect their young. In field studies on St. Paul Island, Alaska, nine of 17 female northern fur seals observed entangled in debris never returned to their pups after foraging at sea (Fowler, 1988). The other entangled seals took twice as long to return as did unencumbered female seals (Fowler, 1988). Sea turtles also appear to be prone to entanglement in plastic debris. In the first comprehensive assessment of this problem, carried out by the NMFS, Balazs (1985) complied a list of 60 cases of sea turtle entanglements worldwide involving green, loggerhead, hawksbill, olive ridley, and leatherback turtles. The debris involved most often was monofilament fishing line. Other cases involved (in order of decreasing frequency) rope, trawl nets, gillnets, and plastic sheets or bags. As is the case for pinnipeds, entangled sea turtles are unable to carry out basic biological. functions such as feeding, swimming, or surfacing to breath; constricting debris also may cause lesions or even necrosis of flippers. According to Bourne (1990); however, there appears to be no evidence that the entanglement of turtles in debris is affecting their numbers, in contrast to the significant effects of other threats such as drowning in shrimp trawls, overfishing, direct harvesting for meat and eggs, disturbance of breeding habitat, and ingestion of debris. While pinniped and sea turtle entanglement in plastic debris has been documented, accounts of the impact of plastics on birds are entirely anecdotal. There has been no attempt by any agency to collect extensive data on bird mortality due to entanglement in debris. In the past, the entanglement problem has been overshadowed by the magnitude of seabird mortality related to active fishing operations, principally in the high seas drift-net fisheries in the Pacific. For example, the Japanese salmon gillnet fishery, in which more than 2,575 kilometers (km) (1,600 miles) of drift gill net were set each night, reportedly drowned over 250,000 seabirds in U.S. waters each year during a two-month fishing season (King, 1984). An international moratorium was enacted recently on high seas drift-gillnet fishing. Seabirds also are attracted to lost or discarded nets and have been found entangled in large pieces of lost gillnets that continue to ghost fish at sea (Jones and Ferrero, 1985).

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea Based on anecdotal reports, monofilament fishing line may be the item most often known to entangle birds. During the 1991 and 1992 International Coastal Cleanups coordinated by the Center for Marine Conservation (CMC), 56 of the 120 reported cases of bird entanglements involved fishing lines (Younger and Hodge, 1992; Hodge et al., 1993). It should be noted that these animals were reported on just a fraction of the U.S. coastline within a few hours. Hence, it would seem worthwhile to investigate just how serious a problem monofilament line poses to birds. In some cases, birds may become entangled in fishing lines when they attempt to eat bait from fishing hooks. An entangled bird trailing line either may be immobilized immediately or may become snagged on a tree or power line, unable to break free. Other items, such as plastic six-pack rings, get stuck around the necks of marine birds and waterfowl when they attempt to dive or feed through the rings. Ospreys, cormorants, and other birds actively collect pieces of nets and fishing line for nest material; this activity can lead to strangulation of both adults and their young (O'Hara and Iudicello, 1987; Podolsky and Kress, 1990). Little is known about the extent of entanglement among species of cetaceans. The lack of knowledge may be due to the fact that these animals are only found on occasions when they wash ashore, added to the expense of and sometimes lack of expertise for conducting necropsies. Information on the entanglement of fish in marine debris is largely anecdotal at present. During the 1992 International Coastal Cleanup, volunteers reported approximately 20 cases of entanglement of fish and crustaceans in debris in just three hours. The range of items found to ensnare fish is remarkable. The CMC maintains a photograph library of wildlife interactions with debris that includes pictures of a gar and bluefish in plastic six-pack rings, sharks in plastic straps and cables, a red drum in a plastic vegetable sack, and a bill fish with a plastic baby bottle cap on its bill. Finally, there have been sporadic accounts of debris on coastlines entangling terrestrial species, For example, foxes and rabbits have been observed entangled in nets and other plastic items (Fowler and Merrell, 1986; O'Hara and Younger, 1990). In one case, the skeletal remains of 15 reindeer were found in á Japanese gill net on a beach in Alaska (Beach et al., 1976). But again, this information is not compiled by any agency. INGESTION OF PLASTICS BY MARINE SPECIES Along with increasing reports of wildlife entanglement involving plastic debris, there has been growing documentation of a less obvious problem: the ingestion of plastics by marine species. There appears to be some understanding of the factors that may increase the likelihood of plastic ingestion by certain species. For example, winds and currents that tend to concentrate food sources such as fish and plankton also concentrate debris. For some species, floating

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea items actually may resemble authentic food items. Seabirds, for example, are thought to mistake small pieces and fragments of plastic for planktonic organisms, fish eggs, or even the eyes of squid or fish (Day et al., 1985). Plastics covered with fish eggs or encrusting organisms such as barnacles, algae, and bryozoa may even "smell" or "taste" like authentic food. It has been suggested that hungry animals are less likely than are satiated animals to discriminate between natural foods and look-alike debris and are more likely to eat the plastic items (Balazs, 1985). Perhaps the most highly publicized example of plastic ingestion has been the consumption of plastic bags or sheeting by sea turtles that are thought to mistake these items for jellyfish, squid, and other prey. In the only comprehensive review of this subject, Balazs (1985) reported five species of sea turtles known to ingest plastics: green, loggerhead, leatherback, hawksbill, and Kemp's ridley. Of the items ingested, plastic bags and sheets were most common (32 percent of 79 cases) followed by tar balls (20.8 percent) and plastic particles (18.9 percent). On San Jose Island, Texas, Amos (1993) reported that 20 to 30 percent of plastic containers that wash ashore exhibit bite marks from turtles. Plotkin and Amos (1990) reported ingestion of plastic and other man-made debris by 46 percent of 76 sea turtles stranded on Texas beaches in an 18-month period. Items found in turtle guts included plastic bags, foamed plastic "peanuts," balloons, strapping band fragments, polypropylene rope, as well as miscellaneous plastic pieces. In some cases, the stomach and gut were completely impacted with plastic. The angular shapes and the rigidity of some of the plastic pieces are not dissimilar to fragments of natural prey that must be excreted, such as crustacean carapaces and sea-pen stalks. Recent studies suggest that young turtles that congregate to feed in the open ocean at areas of convergence are particularly prone to ingesting plastics. The downwelling in these areas concentrates not only turtle food but also plastic debris. For all turtles species, with the exception of the leatherback (which is rarely seen in immature stages), reports of immature animals that have ingested debris are more common than are reports of adults (Balazs, 1985). Cart (1987) noted that plastic pellets found in the stomachs of dead juvenile sea turtles are similar in size and shape to sargassum weed, which concentrates in areas of convergence and provides both shelter and sources of food for turtles. The effect of plastics ingestion on sea turtle longevity and reproductive potential is unknown. It is thought that ingested plastics may cause mechanical blockage of the digestive tract, starvation, reduced absorption of nutrients, and ulceration. Buoyancy caused by plastics also could inhibit diving activities needed for pursuit of prey and escape from predators (Balazs, 1985). For several reasons—the prevalence of plastic ingestion among sea turtles, the significant lesions and mortality caused by ingested items, and the fact that all species of sea turtles are threatened with extinction—the effects of ingestion of debris on sea turtles is considered a research priority (Sileo, 1990).

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea The ingestion of plastic debris by seabirds also has received attention in recent years. The first documented report of plastic ingestion by a seabird, a Layson albatross, was in the 1960s (Kenyon and Kridler, 1969). Today, at least 80 of the world's 280 seabird species are known to ingest plastic debris (Harrison, 1983). This tendency appears to be closely related to bird feeding habits, with diving birds having the highest incidence of plastic ingestion. Most bird species also exhibit preferences for certain types of plastic based on debris color, shape, or size. For example, the parakeet auklet, which feeds primarily on planktonic crustaceans, was found to ingest large amounts of light-brown plastic particles that are similar in size and shape to its crustacean prey. Some birds also feed plastics to their young. In one study, all of the 300 Layson albatross chicks examined on Midway Islands of Hawaii (located more than 1,600 km [1,000 miles] northwest of the nearest populated Hawaiian islands) had ingested plastic debris, including plastic fragments, toys, bottle caps, balloons, condoms, and cigarette lighters (Sileo et al., 1990). Although many birds naturally digest and regurgitate hard, nonfood items such as: fish bones and bottom substrate, some researchers believe that large quantities of ingested plastics may cause intestinal blockage or a false feeling of satiation or may reduce absorption of nutrients, thus robbing the animal of needed nutrition (Day et al., 1985). Suffocation, ulceration, or intestinal injury could be caused by jagged edges on plastics or grinding of these items against intestinal walls. Long-term effects Of plastics ingestion may include physical deterioration due to malnutrition, decreased reproductive performance, and the inability to maintain energy requirements (Day et al., 1985). Limited data are available concerning ingestion of plastic debris by marine mammals, although information from marine parks and zoos suggests that debris ingestion has the potential to be a direct cause of mortality (Walker and Coe, 1990). Several species of wild cetaceans have been found to ingest plastics, primarily in the form of bags and sheeting (Martin and Clarke, 1986; Barros et al., 1990; Walker and Coe, 1990). Because most of this information was obtained through studies of dead animals that had stranded, the actual cause of death is uncertain. In Texas, however, a stranded pygmy sperm whale, which was taken into captivity, died later from the effects of plastic garbage bags, a bread wrapper, and a corn chip bag ingested while in the wild (O'Hara et al., 1987). Analyses of the stomach contents of sperm whales at an Icelandic whaling station from 1977 to 1981 revealed plastic drinking cups and children's toys as well as large pieces of fishing nets. Because sperm whales readily ingest and subsequently regurgitate the hard parts of prey, principally fish bones and cephalopod beaks, small pieces of plastic are thought to pose no significant problem. But in one case, an ingested fishing net weighing 139 pounds was considered to be large enough to cause eventual starvation of the sperm whale. Other marine mammals that have died as a result of ingestion of debris include a northern elephant seal and a Steller sea lion (Mate, 1985). Walker and

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea Coe (1990) also point out that, at least in the case of some species of cetaceans, debris that sinks continues to pose a threat to wildlife; the sperm whale, Baird's beaked whale, and the grey whale, all species of odontocete cetaceans that spend some time feeding on the bottom, are known to ingest non-buoyant debris. The value of using existing procedures to compile and maintain a database on wildlife interactions with debris is demonstrated by a recent report on plastic ingestion by the West Indian manatee, an endangered species. In the southeastern United States, dead manatees routinely are salvaged to determine cause of death and collect biological information. In Florida, personnel from the U.S. Fish and Wildlife Service and the University of Miami have performed systematic necropsies on dead manatees. Using this information, Beck and Barros (1991) found that of 439 manatees necropsied between 1978 and 1986, 63 (14.4 percent) had ingested debris. Pieces of monofilament fishing line were the most common debris items ingested (49 manatees). Other items included string, twine, rope, fish hooks or wire, paper, cellophane, synthetic sponges, rubber bands, plastic bags, and stockings. Finally, Hoss and Settle (1990) compiled a list based on existing literature and their own work of at least 20 fish species reported to ingest plastics. This list included reports of larva, juvenile, and adults from benthic to pelagic habitats. Adults had ingested a wide variety of items, including rope, plastic pellets, packaging, sheeting, cups, cigar holders, a bottle, and colored fragments. Bart (1990) reported plastics in 12 percent of the yellow fin tuna and 3 percent of the blue fin tuna caught off the coast of Virginia. Higher percentages of plastics found in these and other pelagic species have been attributed to more frequent association of these fish with areas where debris concentrates, such as in drift lines. GHOST FISHING A major problem that ultimately could affect marine ecosystems, as well as create a major economic concern, is ghost fishing—the capability of lost or discarded fishing gear to continue to catch finfish and shellfish species indefinitely. Unfortunately, this is a difficult problem to study and there are few quantitative data on the subject. Because individuals fishing in the United States are not required to report lost fishing gear, there is no way to determine and monitor the total amount of lost fishing gear and its potential impacts on U.S. fishery resources. However, the potential for impact on fishery resources and economics can be demonstrated for one segment of the fishing industry—the inshore lobster fishery of Maine. For this fishery, it has been estimated that 25 percent of all traps are lost each year, and that each lost trap can continue to catch up to 1.2 kilograms (2.5 pounds [lbs.]) of lobster (Smolowitz, 1978). While this may not seem significant, the cumulative effect could be; of the 1,787,795 lobster pots used in Maine's inshore fishery in 1987, nearly 450,000 traps were lost. Accordingly, those lost

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea traps had the potential to catch more than 499 metric tons (MT) (1.1. million lbs.) of lobster valued at approximately $2.7 million dollars (1987 landings for this fishery were 10.160 MT [22.4 million lbs.] valued at $54.5 million [Natural Resources Consultants, 1990]). Gillnets have also been found to have a significant potential to ghost fish. According to one estimate, lost gillnets can fish at a 15 percent effectiveness rate for up to eight years (Natural Resources Consultants, 1990). These lost nets not only pose a threat to marine wildlife in general but also can deplete species, including striped bass populations in the north Atlantic and south Atlantic, red drum in the Gulf of Mexico, and salmon and lake trout in the Great Lakes. At present, the effects of ghost fishing related to U.S. commercial fisheries cannot be addressed due to the inadequacy of available information. There are no data on the number of gear units deployed in various fisheries, the number lost, or the capability of various types of gear to ghost fish (Natural Resources Consultants, 1990). The cumulative effects of lost gear also need to be considered. In addition, the effects of the increasing use of plastic or plastic-coated wire traps need to be examined, as these trends could prolong the capability of traps to ghost fish. DATA ON ECOLOGICAL EFFECTS Limited data are available on the ecological impacts of marine debris, and the information that has been collected is uneven and incomplete. The broad impact of plastics on ecosystems is unknown. Pinniped and sea turtle entanglement in plastic debris have been documented, but accounts of the impact of plastics on birds, fish, marine mammals, and terrestrial species are largely anecdotal. Furthermore, most available data on wildlife entanglements with debris is drawn from a few studies, and there has been no attempt to compile the data at one source, nor has there been any extensive effort to monitor trends. Some data has been compiled by the NMFS, which collects information on entanglements involving certain species. In fact, the only way in which information on wildlife interactions with debris is formally exchanged among researchers and agencies, and in some manner compiled, is through the workshops and resultant proceedings coordinated by the NMFS. It is clear that research on the ecological effects of marine debris would be facilitated by a centralized system for keeping track of relevant data on all species. The value of systematically compiling and maintaining a database on debris interactions with wildlife is demonstrated by the West Indian manatee program. REFERENCES Amos, A.F. 1993. Solid waste pollution of Texas beaches: a Post-MARPOL Annex V study, Vol 1: Narrative. OCS Study MMS 93-43013. Available from the public information unit of the U.S.

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Clean Ships Clean Ports Clean Oceans: Controlling Garbage and Plastic Wastes at Sea Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, La. July. Anonymous. 1981. Galapagos tainted by plastic pollution. Geo 3:137. Araya, H. 1983. Fishery biology and stock assessment of Ommastrephes bartrami in the North Pacific Ocean. Mem. of the National Museum in Victoria (Australia) 44:269-283. Balazs, G.H. 1985. Impacts of ocean debris on marine turtles: entanglement and ingestion. Pp. 387-429 in Proceedings of the Workshop on the Fate and Impact of Maine Debris, 27-29 November 1984, Honolulu, Hawaii (Vol. I), R.S. Shomura and H.O. Yoshida, eds. NOAA-TM-NMFS-SWFC-54. Available from the Maine Entanglement Research Program of the National Maine Fisheries Service (National Oceanic and Atmospheric Administration), Seattle, Wash. Barr, C. 1990. Preliminary evaluation of feeding of blue fin tuna (Thunnus thynnus) and yellowfin tuna (Thunnus alabacares) off the coast of Virginia . Gloucester Point, Va.: Virginia Institute of Maine Science. Barros, N.B., D.K. Odell, and G.W. Patton. 1990. Ingestion of plastic debris by stranded marine mammals in Florida. P. 746 in Proceedings of the Second International Conference on Marine Debris, 2-7 April 1989, Honolulu, Hawaii (Vol. I), R.S. Shomura and M.L. Godfrey, eds. NMFS NOAA-TM-NMFS-SWFSC-154. Available from the Maine Entanglement Research Program of the National Maine Fisheries Service (National Oceanic and Atmospheric Administration), Seattle, Wash. Beach, R.J., T.C. Newby, R.O. Larsen, M. Penderson and J. Juris. 1976. Entanglement of an Aleutian reindeer in a Japanese fish net. Murrelet 57(3):66. Beck, C.A. and N. B. Barros. 1991. The impact of debris on the Florida manatee. Maine Pollution Bulletin 22(10):508-510. October. Bourne, W.R.P. (chair). 1990. Report of the working group on entanglement of marine life. Pp. 1207-1215 in Proceedings of the Second International Conference on Maine Debris, 2-7 April 1989, Honolulu, Hawaii (Vol. II), R.S. Shomura and M.L. Godfrey, eds. NOAA-TM-NMFS-SWFSC-154. Available from the Marine Entanglement Research Program of the National Marine Fisheries Service (National Oceanic and Atmospheric Administration), Seattle, Wash. Bourne, W.R.P. and M.J. Imber. 1982. Plastic pellets collected by a prion on Cough Island, central South Atlantic Ocean . Maine Pollution Bulletin 13(1):20-21. Calkins,.D.G. 1985. Steller sea lion entanglement in marine debris. Pp. 308-314 in Proceedings of the Workshop on the Fate and Impact of Maine Debris, 27-29 November 1984, Honolulu, Hawaii, R.S. Shomura and H.O. Yoshida, eds. NOAA-TM-NMFS-SWFC-54. Available from the Maine Entanglement Research Program of the National Maine Fisheries Service (National Oceanic and Atmospheric Administration), Seattle, Wash. Carr, A. 1987. Impact of nondegradable marine debris on the ecology and survival outlook of sea turtles. Maine Pollution Bulletin 18(6B):352-356. Day, R.H., D.S. Wehle, and F.C. Coleman. 1985. Ingestion of plastic pollutants by marine birds. Pp. 344-386 in Proceedings of the Workshop on the Fate and Impact of Marine Debris, 27-29 November 1984, Honolulu, Hawaii, R.S. Shomura and H.O. Yoshida, eds. NMFS NOAA-TM-NMFS-SWFC-54. Available from the Maine Entanglement Research Program of the National Marine Fisheries Service (National Oceanic and Atmospheric Administration), Seattle, Wash. Fowler, C.W. 1985. An evaluation of the role of entanglement in the population dynamics of Northern fur seals. Pp. 291-307 in Proceedings of the Workshop on the Fate and Impact of Maine Debris, 27-29 November 1984, Honolulu, Hawaii, R.S. Shomura and H.O. Yoshida, eds. NOAA-TM-NMFS-SWFC-54. Available from the Maine Entanglement Research Program of the National Maine Fisheries Service (National Oceanic and Atmospheric Administration), Seattle, Wash. December. Fowler, C.W. 1988. A review of seal and sea lion entanglement in marine fishing debris. Pp. 16-63 in Proceedings of the North Pacific Rim Fishermen's Conference on Maine Debris, October 13-

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