Arthropods contributed from 7.7 to 46.3% of the diet 

 depending on the geographic area, but in all cases amphipods 

 were the most important category of crustaceans. Amphipod 

 tubes accounted for a fair percentage of this prey group in four 

 o; the five areas: Southern New England (20.3%), Georges 

 Bank (18.6%), Gulf of Maine (13.8%), Middle Atlantic (7.9%), 

 and Western Nova Scotia (0.7%). The Corophiidae and the 

 C unmai dae were the most important families of amphipod 

 prey in a., areas. In three areas, the Gammaridae were more im- 

 portant than the Corophiidae, 9.1% vs. 6.0%, 8.7% vs. 2.5%, 

 6.1% vs. 3.1% for Southern New England, the Middle Atlantic, 

 and Georges Bank, respectively. In the Gulf of Maine, cor- 

 ophiids (10.3%), especially Unciola (8.8%), were preyed on 

 more heavily than the Gammaridae (1.0%), and in Western 

 Nova Scotia the Lysianassidae (3.6%) were more important 

 than the Corophiidae (2.5%). 



Other major taxa were of secondary importance in the 

 yellowtail diet when compared with the annelids and arthro- 

 pods. In certain geographic areas, however, specific taxa con- 

 tributed significantly to the diet. For example, in the Gulf of 

 Maine, 21.0% of the stomach contents were identified as 

 echinoderms, and the sea cucumber, Stereoderma unisemita, 

 accounted for almost all (20.9%) of these remains. Stereoderma 

 unisemiia (0.1%) were also preyed on in Western Nova Scotia, 

 but in the remaining three areas, Middle Atlantic, Georges 

 Bank, and Southern New England, the sand dollar, Echina- 

 rachnius punua, was the most important echinoderm prey 

 (2.5, 1.8, 1.5%, respectively). Like echinoderms, Cnidaria were 

 important prey in one or two of the areas. On Georges Bank, 

 actinarians (5.2%) and the ceriantharians (5.1%) [Cerianthus 

 (3.4%)] were members of the two orders of coelenterate prey 

 identified. In Western Nova Scotia, the Actinaria (5.1%) again 

 accounted for a majority of the coelenterates eaten. Among the 

 "Other Groups" category, the Ascidiacea was the taxon that 

 made the largest contribution. In the Gulf of Maine, 

 Cnemidocarpa (6.5%) accounted for most of the prey in this 

 class, and in Southern New England Cnemidocarpa (0.1%) and 

 Mogula (1.2%) were identified among the ascidian remains 

 (3.4%). In the Middle Atlantic (1.5%) and on Georges Bank 

 (1.2%), ascidians were also preyed on, but none were identifi- 

 able below the class level. Pisces were of very little importance as 

 prey in any of the areas, although in the Middle Atlantic an 

 unidentified cottid (2.4%) and a shanny, Lumpenus maculatus 

 (0.1%), were found in the stomach contents. 



Winter Flounder. — When all five geographic areas are consi- 

 dered together (Table 8), the prey of winter flounder is generally 

 divided among three taxa: Annelida, Cnidaria, and Mollusca. 

 On a regional basis, however, the diet is quite variable, with dif- 

 ferent taxa being important in the different areas even when the 

 average fish length is similar. These differences may be a reflec- 

 tion of regional changes in feeding activity or at least prey avail- 

 ability and are therefore discussed below. 



Winter flounder collected in the Middle Atlantic preyed 

 heavily on Cnidaria (52.8%). Most of the cnidarians were identi- 

 fied to the order level as Actinaria (48.8%) or Ceriantharia (1 .0%), 

 although a small percentage were placed in the class Hydrozoa 

 (3.0%). In the other geographic areas, most of the cnidarians 

 were also identifiable at the order level. On Georges Bank, for 

 example, where 30.4% of the diet was coelenterates, the 

 cnidarian prey were identified as Actinaria (16.1%), Ceriantharia 

 (0.4%), or as unidentified Anthozoa (8.3%) or Hydrozoa (5.7%). 

 In Western Nova Scotia, the anthozoan prey were again 



broken down into Ceriantharia (9.3%) and Actinaria (3.1%), 

 while in Southern New England the Ceriantharia (9.9%) was the 

 only representative of this class. 



Annelids were a major prey in all of the geographic areas, 

 accounting for 15 to 60% of the diet in any one area. In the 

 Middle Atlantic, 44.1% of the diet was annelids and most of 

 these were identified only at the phylum level (36.2%). In the 

 other regions, the greater proportion of the annelids could 

 usually be identified from the partially digested remains 

 although a percentage were always only recognizable at the 

 phylum level: Gulf of Maine (23.3%), Southern New England 

 (7.7%), and Georges Bank (5.7%). Three groups of annelids 

 were identified in the stomachs of winter flounder from the 

 Middle Atlantic. The Goniadidae accounted for 3.7% of the 

 diet, and the two polychaetes identified at a generic level were 

 Lumbrineris (2.1%) and Nereis (2.1%). Lumbrineris (1.1%) 

 was also identified in flounder stomachs from Southern New 

 England, and Nereis made up 2.3% of the diet of the fish from 

 the Gulf of Maine, although small quantities of these genera of poly- 

 chaetes were also found in the stomachs from all otha areas . Represen- 

 tatives of the Goniadidae were found in the winter flounder sto- 

 machs from Southern New England, Ophioglycera giganlea 

 (8.2%), and in the Gulf of Maine, Goniada (8.4%) [Goniada 

 norvegica (4.6%)]. In Southern New England, several other taxa 

 of polychaetes were important prey: unidentified SabeUidae 

 (5.6%) and OpheUidae (3.3%), Ninoe (3.2%), Nephthys incisa 

 (2.9%), and Nicolea venustula (1 .7%). A variety of polychaetes 

 were identified in the winter flounder stomachs from Georges 

 Bank, but only one, Ampharete, made up at least 1.0% of the 

 diet. In the Gulf of Maine, the TerebeUidae (10.2%), especisilly 

 Thelepus cincinnatus (3.4%), were important prey, together 

 with Polydora ciliata (1.8%), Eteone (1.4%), and polychaete 

 tubes (8.4%). The TerebeUidae (37.6%), particularly Thelepus 

 cincinnatus (32.2%), were again important prey in Western 

 Nova Scotia, as were Nicomache lumbricalis (3.9%), Pherusa 

 (2.2%), Chone infundibuliformis (1.1%), and polychaete tubes 

 (2.0%). 



None of the other taxonomic groups were important in all the 

 geographic areas, although in any particular area molluscs, 

 echinoderms, or arthropods were an important prey category. 

 On Georges Bank, for example, bivalve molluscs accounted for 

 20.4% of the diet, but, unfortunately, 19.4% of these could 

 only be identified at the class level. Bivalves were important in 

 three other areas also (Table 8), but most of them were not iden- 

 tifiable below class. In Southern New England, echinoderms 

 were of secondary importance, and this was primarily due to 

 predation on the sea cucumber, Stereoderma unisemita (5.4%). 

 Arthropods accounted for no more than 13% of the diet in any 

 area, and in Southern New England, where they were preyed on 

 most heavily, the rock crab. Cancer irroratus (7.8%) and the 

 caprellid, Aeginina longicornis (1.3%), were the two important 

 prey species. Arthropods were generally not very important in 

 the other areas, except in Western Nova Scotia, where amphi- 

 pods (7.6%) were preyed on and in particular the caprelUd, A. 

 longicornis (2.4%), and the gammarid, Leptocheirus pinguis 

 (1.8%). 



DISCUSSION 



Food 



Gulf Stream flounder. — The authors know of no published 

 reports on the food of the Gulf Stream flounder, Citharichthys 



11 



