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any stomach content data. Sources of potential bias or 

 variation in the data include age/size, sex, maturity stage, 

 and various sampling factors (i.e., time of day, season, year, 

 area, and bottom depth and temperature). Accordingly, di- 

 etary listings should be considered only as broad summa- 

 ries. Some items listed as stomach contents are parasites 

 (e.g., trematodes, cestodes, and nematodes), some of which 

 may have been ingested by the predator when it ate other 

 parasitized organisms. Similarly, some items identified in 

 the stomachs may have originated from the stomachs of 

 fish prey and were not directly consumed by a particular 

 predator. 



Life history and distribution data for many economi- 

 cally important species (e.g., Atlantic cod, haddock, silver 

 hake, and Atlantic herring) may be found in Grosslein and 

 Azarovitz (1982). Details of stomach content sampling pro- 

 cedures and data processing methods utilized by the NEFSC 

 are given in Langton et al. (1980). All common and scien- 

 tific names of fishes and invertebrates (both predator and 

 prey), whenever possible, are according to Robins et al. 

 ( 1 99 1 ) for fishes except pleuronectids, Cooper and Chapleau 

 (1998) for pleuronectid fishes, Turgeon et al. (1988) for 

 mollusks except loliginids, Turgeon et al. ( 1 998) for loliginid 

 mollusks, Williams et al. (1989) for decapod crustaceans. 

 Cairns et al. (1991) for cnidarians and ctenophores, and 

 either Gosner ( 1 97 1 ) or Barnes ( 1 987) for other invertebrates. 



RESULTS AND OBSERVATIONS 



Detailed diet data for each predator species are given in 

 tabular form in Appendices A and B. In the appendix tables, 

 diet composition is expressed as the percentage by weight 

 that each stomach content group makes up of the total stom- 

 ach contents for each predator species (except in a few 

 cases, which are noted in the tables, where percentage by 

 volume or occurrence is given because a different measure- 

 ment method was utilized during the particular study from 

 which those data were taken). Percentage subtotals for 

 phyla and other major taxonomic groups are shown in brack- 

 ets; subtotals for minor groups within major groups are in 

 parentheses. The number sampled, number empty, mean 

 stomach content by weight or volume, and mean predator 

 length are provided at the bottom of each table. 



The stomach contents of 31,567 individual predators, 

 representing 178 species offish and 2 common species of 

 squid were examined. The total number of each species 

 examined and the percentage empty are listed in the earlier- 

 presented taxonomic index. The area(s) in which samples 

 were collected and the type(s) of data which are presented 

 for each species are given in the earlier-presented alpha- 

 betic index. All stomachs of 10 species collected were empty; 

 they are listed at the end of the taxonomic index. 



OVERALL PREY 



A summary of the stomach content data for the 1 70 

 species with food in their stomachs is provided in Table 1 . 

 (Also refer to Appendices A and B for a detailed listing of 

 prey.) The functional prey groups (i.e., fish, squid, poly- 

 chaete, decapod crustacean, other crustacean, and all other) 

 noted immediately below and listed in Table 1 collectively 

 made up at least 50% by weight (or volume) of the stomach 

 contents of the predators indicated. 



Fish and/or squid made up the majority of the stomach 

 contents of 59 species. Identified fish prey, for the most 

 part, were northern sand lance, silver hake, other hakes, 

 herrings, mackerels, butterfish, anchovies, scup, flatfishes, 

 and sculpins. Squid prey were primarily longfin inshore 

 and northern shortfin squids. Polychaetes (mostly spionids, 

 nereids, and nephtyids) were important constituents of the 

 diet of seven species. Decapod shrimp (mainly Pandalus 

 spp., Dichelopandalus leptocerus, and Crangon 

 septemspinosa) and crabs (principally Cancer spp., Pagurus 

 spp., and Ovalipes spp.) were the principal food of ! 7 preda- 

 tors. Crustaceans other than decapods made up a substan- 

 tial portion of the stomach contents of 32 species, and in- 

 cluded prey such as copepods, amphipods, mysids, and 

 euphausiids. Note, however, that some of the unidentified 

 crustacean matter included here may have been decapod 

 remains). The "all other" group (/. e. , stomach contents other 

 than the groups noted above) is primarily made up of some 

 combination of bivalve mollusks, gastropods, echinoderms, 

 cnidarians, urochordates, sand, or unidentified material. This 

 group made up most of the stomach contents of 37 species. 

 Eighteen predator species were diverse feeders and didn't 

 feed predominantly on any one of the above functional 

 prey groups. 



PREY ACCORDING TO PREDATOR LENGTH 



Different diet compositions for fish in different length 

 ranges are observed for 60 species (Appendix B). Gener- 

 ally, fish 20 cm long tended to eat some combination of 

 organisms such as chaetognaths, copepods, amphipods, 

 mysids, polychaetes, and small decapod shrimp. Fish >20 

 cm long (e.g., little skate, Atlantic cod, silver hake, pollock, 

 and white hake) consumed mostly fish, squid, decapod 

 shrimp, and/or crabs. 



Exceptions to this pattern are seen in three groups of 

 predators. The first group are those species which fed 

 intensively on fish and/or squid for most of their life. Preda- 

 tors in this group included, in part, northern shortfin and 

 longfin inshore squids, most of the sharks (e.g., dusky shark, 

 sharpnbse shark, and spiny dogfish), goosefish, and blue- 

 fish. 



