Taylor el al Habitat use by summer spawned Pomatomus saltatnx on the inner continental shelf off southern New Jersey 



597 



bluefish in length-frequency 

 histograms. Summer-spawned 

 bluefish were defined as <100 

 mm SL in August, <125 mm SL 

 from early to mid-September, 

 <150 mm SL from mid-to-late 

 September, <175 mm SL from 

 October to November. Bluefish 

 at body sizes larger then these 

 groupings were designated as 

 spring-spawned individuals. 



Results 



Bluefish density and mean size 

 on the Inner continental shelf 



A total of 1071 bluefish were col- 

 lected from surface waters off 

 the southern coast of New Jersey 

 during the survey. Throughout 

 the August-October sampling 

 period, bluefish were found in 

 71'7f ofthetows(99outof 140), 

 during which the mean den- 

 sity was 3.7 bluefish/1000 m^ 

 (range = 0-57.9 bluefish/1000 

 m^). Bluefish density differed 

 significantly by transect and 

 sampling date (multivariate 

 repeated-measures ANOVA; 

 transect: F=9.39, df=3,12. 

 P<0.005; date: F=16.09, df=9,88, 

 P<0.0001). However, the tran- 

 sect-sampling date interac- 

 tion effect was significant and 

 precluded direct conclusions 

 about the main effects (mul- 

 tivariate repeated-measures 

 ANOVA; transect X date: F= 

 1.95, df=27,88, P<0.05) (Fig. 2). 

 The interaction effect was 

 attributed to significantly 

 higher densities of bluefish at 

 transect II on days 226 and 268 

 (in comparison to transects I, 

 IV, and transect I on these days, 

 respectively ( Ryan's Q multiple 

 comparison test). Bluefish den- 

 sities were also significantly 

 greater at transect III on days 

 226 and 244 than at transect I 

 for both dates (Ryan's Q mul- 

 tiple comparison test). 



In the stepwise multiple 

 regression, Secchi depth ex- 

 plained the most variability 

 in bluefish density with an 

 r^ of 0.078 (stepwise multiple 



8/11/98 

 day 223 



N 



8/12/98 

 day 224 



8/1 4/98 



^ /7 O day 226 



- bo°o 



 O o 



eft ° 



O X 



o 



8/1 8/98 

 O day 230 



O 



O '^ 



8/20/98 

 day 232 



,, 9/25/98 



^ O^ o 



o 



o 



T 



Figure 2 



Spatial distribution of the density (no. offish/1000 m-^) of bluefish (Pomatomus sallatrix) 

 collected with a Methot trawl between 11 August and 9 October 1998 off the southern 

 coast of New Jersey. Stations were located at approximately .39 27'N, 74 ll'W. 



