44 



Fishery Bulletin 97(1), 1999 



25 



I male 

 n female 

 I undetermined ! 



95 115 135 155 175 



 Dliul I 



95 215 235 255 275 295 315 



Total length (mm) 



Figure 4 



Length-frequency distribution of males, females, and undetermined sexes collected during the 

 GM 93-20 survey between 2 August and 13 August 1993 plotted in groups of 5. (/i=727). 



28.7% and was replaced by bivalves (56.3%) in fish 

 ranging from 2 to 7 years old (Table 5). Polychaetes 

 (2.0%) and decapods (3.7%) were found only in the 

 stomachs of older fish. Cumaceans made up a small 

 percentage of the diet in both size ranges. 



Bivalves (80.0%) and copepods (80.0%) were the 

 most frequent items encountered in 1-year-olds, with 

 cumaceans (40.0% ) third in importance (Table 5). The 

 frequency of bivalves (71.0%) in the diet of older fish 

 was similar to that of 1-year-olds. Decapods and poly- 

 chaetes were consumed in higher frequency in larger 

 fish. Copepods were eaten in large numbers in both 

 size categories but were taken less frequently by 

 larger fish ( 12.9%). 



Parasitism 



Four parasite species were identified for the first time 

 for this host. The nematodes were identified as all 

 second- or third-stage and third- or fourth-stage lar- 

 vae of the family Raphidascarinidae, probably 

 Hysterothylacium sp. These identifications were 

 based on the presence of a boring tooth, globular ven- 

 triculus, ventricular appendage, intestinal caecum, 

 and excretory pore near the nerve ring. Raphi- 

 dascarinidae sp., located mainly in the body cavity, 

 were found to have the highest prevalence (23.0%) 

 of all parasites surveyed (Table 6). 



Encysted plerocerci larvae were identified as 

 Grillotia erinaceus Van Beneden, 1858 and were 

 found in the body cavity, stomach, and intestine of 

 20.9% of the fish examined. 



The two species of digenetic trematodes, found in 

 the stomachs of £. cir7ibrius collected during the GM 

 94-12 survey, were identified as Genolinea laticauda 

 Manter, 1925 and Gonocerca phycidis Manter, 1925. 

 Body length dimensions of two specimens of G. 



