502 



Fishery Bulletin 92(3). 1994 



for all indices: 80.0% (F), 67.7% (N), 85.0% (W), and 

 88.6% (Wl). Crustaceans composed 24.0% (F), 32.3% 

 (N), 15.0% (W), and 11.4% (Wl). 



Bluefish measuring 37-64 mm FL were captured 

 from Sagadahoc Bay on 10 and 22 August 1990. The 

 predominant prey items recorded from these small 

 juveniles were crustaceans (mysids and copepods). 

 The frequency of occurrence of mysids and copepods 

 in stomachs containing food (F) was 10.3% and 96.6%, 

 respectively. Crustaceans were also the predominant 

 prey items in terms of their wet or dry weight, ex- 

 pressed as a percentage of the total wet weight (W) 

 or dry weight (Wl). Crustaceans composed 82.2% of 

 the total wet weight (W) and 80.0% of the total dry 

 weight ( Wl ). Fish remains were a minor constituent 

 of the stomach contents of these small bluefish; they 

 occurred in 6.9% of stomachs containing food (F). Fish 

 also composed 17.7% of the total wet weight (W) and 

 21.0% of the total dry weight (Wl). No information 

 was available regarding the numbers of individuals 

 observed (N) expressed as a percent of the total num- 

 ber of prey items recorded because copepod remains 

 were so numerous that it was impractical to count them. 



The diet of juvenile bluefish collected from the 

 Marsh River in 1990 and 1991 and from Merepoint 

 Bay in 1991 is consistent with observations by Breder 

 (1922), Grant (1962), data for bluefish >10 cm re- 

 ported by Smale and Kok (1983), and the 1981 re- 

 sults recorded in Friedland et al. ( 1988). All studies 



showed that the major portion of the diet (by weight 

 or volume) of juvenile bluefish >8 cm in length con- 

 sisted offish. Although results presented by Lassiter 

 (1962) and Naughton and Saloman (1984) are also 

 consistent with this observation, Lassiter ( 1962 ) did 

 not report bluefish lengths and some of the bluefish 

 in Naughton and Saloman's (1984) data were older 

 than age 1 (e.g. 39.9 cm). 



Our findings regarding the diet of juvenile blue- 

 fish collected from Sagadahoc Bay (1990) were con- 

 sistent with results presented by Kendall and Naplin 

 (1981) and Smale and Kok (1983) for bluefish <100 

 mm. Smale and Kok (1983) reported that juvenile 

 bluefish <100 mm feed predominantly on small crus- 

 taceans, and Kendall and Naplin (1981) stated that 

 most of the diet of juvenile bluefish (.r=4.33 mm) 

 consisted of copepods, copepodites, cladocera, and fish 

 eggs. A transition to pisciverous feeding by juvenile 

 bluefish at a size range between 60 and 100 mm has 

 been reported (Nichols, 1913; Greeley, 1939; Oben, 

 1957; Clark, 1973; Smale and Kok, 1983). The tran- 

 sition to fish as prey had not yet occurred in bluefish 

 measuring 37-64 mm from Sagadahoc Bay (Table 3). 



On a per cent weight basis, the dominant prey spe- 

 cies of juvenile bluefish (81-200 mm FL) collected 

 from the Marsh River and Merepoint Bay included 

 the mud shrimp Crangon septemspinosa, juvenile 

 alewives, Alosa pseudoharengus , unidentified clu- 

 peids, Atlantic silversides, Menidia menidia, mum- 



