Buckel et al.: Foraging habits of Pomatomus saltatnx 



767 



200 300 400 500 600 700 800 



Bluefish fork length (mm) 



Figure 2 



Prey total length ( mantle length for squid ) versus adult 

 bluefish fork length in (A) 1994 iprey TL=0.199 ' blue- 

 fish FL-14.413, r2=0.15. P<0.001) and (B) 1995 iprey 

 TL=0.205 X bluefish FL-9.047. r2=0.28, P<0.0001). 

 "Other" prey include searobin, red hake, silver hake, 

 unidentified gadid, scup, windowpane, haddock. North- 

 ern puffer, conger eel, cusk eel, sand lance, striped an- 

 chovy, spot, weakfish, Atlantic mackerel, fourbeard 

 rockling, and ocean pout. 



however, the prey length to predator length ratios of 

 summer-spawned bluefish in 1995 are values at 

 which bluefish have relatively lower capture success 

 (Fig. 3). 



In 1994, there were four stations that had n>15 

 bay anchovy measurements for both spring and sum- 

 mer-spawned bluefish (/i = 16-20 bay anchovy mea- 

 surements for summer- and /! =22-39 for spring- 

 spawned). Both spring- and summer-spawned YOY 

 bluefish showed significant selection for relatively 

 small bay anchovies (spring-spawned a=0.57 vs. 0.25, 

 ^=2.99, df=38, P=0.005; summer-spawned a=0.65 vs. 



0.50 ~[ 



0.45 - 



0.40 



0.35 



0.30 



0.25 



0.20 



015 



0.10 H 



0.05 



Spring-spawned 

 Summer-spawned 



1.0 

 08 

 h 0.6 

 0.4 

 0.2 



'P^^r I — r- 



1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 



0.1 02 3 0.4 0.5 0.6 07 08 



Bay anchovy FL: bluefish FL ratio 



Figure 3 



Bay anchovy FL to bluefish FL ratios for both sphng-and sum- 

 mer-spawned bluefish in (Al 1994 and (B) 1995. Regression 

 line for capture success versus prey length to predator length 

 ratio from Scharfet al. (1998b). 



0.33, ^=2.61, df=27, P=0.011) and avoidance of rela- 

 tively larger anchovies in 1994 (spring-spawned 

 a=0.02 vs. 0.25, ^=3.83, df=38, P<0.001: summer- 

 spawned a=0.07 vs. 0.33, ;'=2.86, df=27, P=0.006) 

 (Table 7). Intermediate-size bay anchovy were taken 

 in proportion to their abundance in 1994 (^-test; 

 P>0.05 for all or's). In the 1995 analysis, three sta- 

 tions had n>15 individual bay anchovy lengths 

 (« = 17-32); an analysis of size-selective feeding of 

 summer-spawned fish in 1995 was not possible ow- 

 ing to small sample size. Spring-spawned bluefish 

 in 1995 showed no significant size selectivity (^test; 

 P>0.05 for all or's); however, the trend of increasing 

 selectivity with decreasing prey sizes was present 

 (Table 7). 



