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Fishery Bulletin 97(1), 1999 



weight followed by animal remains (30.1'^) and in- 

 fauna, primarily polychaetes (13.6%) (Langton and 

 Bowman, 1980). Decapod crustaceans were not as im- 

 portant as these other groups to juvenile fish in the 

 present study. Decapods appeared in number for the 

 first time in 2- to 7-year-old fish. This can be explained 

 by the preference for larger prey by older, larger fish. 



In a Norwegian Qord, E. cimbrius between 70 and 

 300 mm TL preyed primarily on crustaceans, poly- 

 chaetes, fish, bivalves and rarely on copepods 

 (Mattson, 1981). In adult rocklings, high percentages 

 of infauna, particularly polychaetes, have been re- 

 ported from the North Sea (Moller-Buchner et al., 

 1984) and Passamaquoddy Bay, where the frequency 

 was found to be correlated with an increase in fish 

 size (Keats and Steel, 1990). The high frequency of 

 infaunal organisms, predominantly bivalves, in the 

 diet of 2- to 7-year-old fish in the present study ex- 

 hibits a similar trend. This finding may be correlated 

 with adults having a sedentary existence and remain- 

 ing in close contact with the substrate (Bigelow and 

 Schroeder, 1953; Cohen et al., 1990). This lifestyle, 

 compounded with the fact that this species has well- 

 developed stout barbels equipped with taste buds 

 (Nagabhushanam, 1965), would enable larger fish 

 to feed more effectively on epifauna and infauna. 



E. cimbrius is best characterized as a euryphagous 

 bottom-rover or "grazer." (Moyle and Cech, 1988). The 

 size of the prey appears to be directly correlated with 

 the size of the predator as seen in the change in diet 

 from 1-year-old fish to those 2 to 7 years of age. 



Parasitism 



The parasite fauna of £. cimbrius consisted of three 

 taxa and four species: Nematoda ( 1 ), Cestoda ( 1 ), and 



Trematoda (2). The prevalence (P^ ) and abundance 

 (A) of a nematode from the subfamily Raphidas- 

 caridinae (probably Hysterothylacium) and a 

 trypanorhynch cestode, G. erinaceus, appear to in- 

 crease with fish age. The P% and A of both digenetic 

 trematodes were low in all age classes. 



The few helminths found were in low abundance. 

 This is uncommon because other gadids are known to 

 have abundant and diverse parasite faunas (Margolis 

 and Arthur, 1979). The very low parasite diversity of 

 E. cimbrius supports evidence of limited movements 

 and benthic feeding preferences in its habitat. 



All nematode specimens of the subfamily Raph- 

 idascaridinae were second- or third-stage and third- 

 or fourth-stage larvae (Measures^. The presence of 

 parasites in the same stage of development are in- 

 dicative of a "grazer" (Dogiel, 1966) and provides 

 additional support to characterize E. cimbrius as 

 such. A similar trend is seen in G. morhua, where its 

 mode of life, generalist feeding habits, and associa- 

 tion with the bottom facilitate the infestation by 

 Raphidascaridinae spp. (Dogiel et al., 1970). 



The increase in prevalence of Grillotia erinaceus 

 from 9.1% at 2 years to 25.0% at 3 years appears to 

 be correlated with the an increase of arthropods in 

 the diet. In the life cycle of G. erinaceus, the 

 plerocercus larvae can be acquired by an intermedi- 

 ate teleost host through consumption of arthropods, 

 mainly copepods, which have previously ingested the 

 tapeworm eggs (Sakanari and Moser, 1985). It is not 

 possible to draw any firm conclusions on this rela- 

 tionship because food habit data in this study did 



' Measures, L. 1995. Maurice Lamontagne Institute, Fisher- 

 ies and Oceans, Mont-Joli (Quebec), Canada G5H 3Z4. Per- 

 sonal comniun. 



