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by weight of several predators). The other two groups, 

 mysids and stomatopods, were important prey in only four 

 of the seven areas sampled (Table 6 and Appendix B). 

 Mysids were important as a food source in the Middle At- 

 lantic, Southern New England, inshore north of Cape 

 Hatteras, and on Georges Bank. Stomatopods were major 

 prey of several predators in the Middle Atlantic, Southern 

 New England, inshore north of Cape Hatteras, and south of 

 Cape Hatteras. 



In the Middle Atlantic, crustaceans other than deca- 

 pods made up >50% of the diet of alewife, haddock (only 

 one fish was examined), and northern sand lance. Southern 

 New England fishes which fed intensively on one or more 

 of the nondecapod crustacean groups noted earlier in this 

 section are alewife, yellowtail flounder, Atlantic mackerel, 

 northern sand lance, and ocean pout. Predators identified 

 for Georges Bank were alewife, Atlantic mackerel, black sea 

 bass, Acadian redfish, and northern sand lance. In the Gulf 

 of Maine, seven predators fed for the most part only on 

 nondecapod crustaceans: Atlantic herring, alewife, Atlan- 

 tic mackerel, summer flounder, Acadian redfish, northern 

 sand lance, and longfin inshore squid). Within the Scotian 

 Shelf area, the stomachs of Atlantic herring, alewife, Atlan- 

 tic mackerel, Acadian redfish, and ocean pout all contained 

 >90% by weight of crustaceans other than decapods. Pre- 

 dation on these crustaceans inshore north of Cape Hatteras 

 was most important to species such as alewife, Atlantic 

 mackerel, northern sand lance, fawn cusk-eel, and window- 

 pane. None of the species examined from waters south of 

 Cape Hatteras had stomachs containing >50% nondecapod 

 crustaceans. 



Hatteras fed primarily on any prey category considered here 

 (i.e., winter flounder eating cnidarians, ocean pout consum- 

 ing echinoderms, and butterfish preying on tunicates, re- 

 spectively). 



OBSERVATIONS 



Scientists at the NEFSC's Woods Hole Laboratory have 

 conducted broadscale dietary studies of fishes sampled 

 during bottom trawl surveys since 1963. Dietary data pre- 

 sented here, which are largely based on samples from the 

 1 977-80 portion of the survey series, corroborate earlier re- 

 ports that relatively few species account for a substantial 

 portion of the food of Northwest Atlantic continental shelf 

 fishes and squids [Edwards and Bowman (1979), Bowman 

 and Michaels (1984), Bowman et al. (1984), Maurer and 

 Bowman (1985)]. The abundances of some species identi- 

 fied as critical prey are known to fluctuate among seasons 

 and years based on indices generated by these surveys. 

 During 1977-80 (i.e., this study's period, in part), when the 

 survey indices rose for northern sand lance, we simulta- 

 neously found sand lance to be a major prey item. 



This report summarizes much dietary information into 

 various predator/prey groups, but that information does 

 not take into account predator/prey population sizes, or 

 spatial/temporal aspects, of predation (i.e., overlap of preda- 

 tor and prey populations). Before the impact of predation 

 on a population can be determined, these factors must be 

 considered. 



A complete list of all stomach contents for all predator 

 species in this report can be obtained from the Food Chain 

 Dynamics Investigation at the NEFSC. 



Other Prey 



Major stomach content categories such as echinoderms, 

 gastropods, bivalve mollusks, chaetognaths, cnidarians, 

 nemerteans (i.e., rhynchocoels), tunicates, animal remains, 

 and sand made up the majority (either individually or in 

 some combination) of what is found in the stomachs of 32 

 predators (Table 7). Of these categories, only those which 

 individually made up >50% of the stomach contents by 

 weight of a predator within a particular area are noted in the 

 remainder of this section (excluding animal remains and 

 sand). 



None of these prey categories totaled >50% of the stom- 

 ach contents of any predator in the Middle Atlantic or 

 Southern New England. On Georges Bank, Atlantic herring 

 fed intensively on chaetognaths, American plaice ate (for 

 the most part) only echinoderms (92.3%), and Atlantic wolf- 

 fish consumed bivalve mollusks. In the Gulf of Maine, echi- 

 noderms were an important food of haddock and ocean 

 pout. Only one predator each within the Scotian Shelf, 

 inshore area north of Cape Hatteras, and area south of Cape 



ACKNOWLEDGMENTS 



Personnel of the NEFSC's Food Chain Dynamics In- 

 vestigation contributing to the compilation of this report, 

 listed alphabetically, were: John Hauser, Brian Hayden, 

 Richard Langton, Lisa Lierheimer, Donald Mack, Ronald 

 Mack, Scott McNamara, Thomas Morris, Jacqueline Murray, 

 James Myette, Stephen Spina, Andrea Swiecicki, and Lynn 

 Whiteley. Eleanore Beale, Elke Bergholz-Nelson, Edward 

 Brown-Ledger, Caroline Karp, Lisa Urry, and numerous sum- 

 mer students and survey technicians helped to collect and 

 analyze stomach contents. Members of the NEFSC's Apex 

 Predators Ecology Investigation deserving special thanks 

 for processing stomach contents and providing data sum- 

 maries are John Casey, Nancy Kohler, and Robert Medved. 

 Jon Gibson, Michael Fogarty, and Russell Brown provided 

 useful suggestions on the organization and content of the 

 manuscript. 



