nektonic feeders include the majority of the Maine coast's summer migrants: 

 bluefin tuna, the hakes (red, white, and silver), spiny dogfish, bluefish, 

 Atlantic mackerel, and striped bass. The dominant demersal feeding fishes 

 include most of the groundfish (e.g., cod, hakes, skates, and flounders), the 

 sculpins, the ubiquitous American eel, the anadromous sturgeons, and the 

 sticklebacks. Major food items are pelagic crustaceans, echinoderms, bottom 

 fish, fish eggs, benthic diatoms, molluscs, and polychaete worms. See chapter 

 11, "Fishes," for a complete description of this group of animals. 



Birds . Waterbirds, including seabirds, shorebirds, wading birds, and 

 waterfowl, use the marine system (including terrestrial islands) for breeding, 

 feeding (among all habitat classes), moulting, migrating, and wintering. 

 Twenty percent of waterbirds are permanent residents. In addition, several 

 raptors, including the resident endangered bald eagle utilize the marine 

 system. Waterbirds are described in detail in chapter 14, "Waterbirds," 

 chapter 15, "Waterfowl," and the bald eagle and other raptors in chapter 16, 

 "Terrestrial Birds." Most species are high level consumers, preying on 

 zooplankton, benthic invertebrates, squid, finfish, and invertebrates and 

 vertebrates of the strand line. Marine waters are the primary breeding and 

 feeding areas for petrels, terns, and alcids. Many pelagic seabirds (i.e., 

 shearwaters, kittiwakes, fulmars, murres , and gannets) are indigenous to 

 marine waters and rarely are found in estuaries. 



The highest densities of waterbirds occur in late summer after the young have 



fledged and during the fall migration (which begins in early July) . Waterfowl 



are most abundant during the fall and spring migrations; shorebirds during the 



fall migration; wading birds during the breeding season and fall migration; 



and seabirds during the summer and fall migration. Peak numbers of shorebirds 

 and seabirds correspond with peak periods of invertebrate productivity. Bald 



eagles occur throughout the year. Peak seasonal abundance is during the 

 spring and summer. 



The role that waterbirds play in energy flow, nutrient cycling, and community 

 structure in the marine system in Maine is unknown. Studies in Oregon on 

 seabird population energy requirements indicated that some 22% of the fish 

 production of the area was utilized by seabirds (Wiens and Scott 1975). In 

 Scotland, Furness (1978) estimates that the total energy requirements of 

 seabirds in a very large colony represents 29% of the mean estimate of the 

 total annual fish production within a 28-mile (45-km) radius of the colony. 

 This implies that seabirds, predatory demersal fish, and industrial fisheries 

 are in direct competition for the energy flow from pelagic fish, so that any 

 increase in the energy flow to one of these would result in a reduced energy 

 availability to the others (Furness 1978). Both studies involved much larger 

 breeding seabird populations than those of coastal Maine. Evans' analysis 

 (1973) of energy flow through the avifauna of the North Sea; based on 

 estimated summer and winter biomass totals of shorebirds, marine waterfowl, 

 and seabirds; concluded that a minimum of 0.01% of the primary production was 

 metabolized by the birds, representing a minimum of 107o of the energy input to 

 the top carnivores (birds and predatory fish). 



4-35 



10-80 



