Buckel and Conover: Movements, feeding, and daily ration of Pomatomus saltatrix 
669 
lections in 1992 (571 spring- and 64 summer- 
spawned) and four in 1993 (633 spring-spawned fish). 
The sample size of bluefish from the 11-12 Septem- 
ber 1993 beach-seine collection was too small (n= 23) 
for all analyses except diet. 
In the forward stepwise multiple-regression analy- 
sis, illumination of the surface waters was the only 
factor that explained a significant amount of the 
variation in spring-spawned bluefish CPUE for both 
1992 (P= 0.006) and 1993 (P<0.001). The influence of 
illumination on CPUE of spring-spawned bluefish 
was positive in both 1992 and 1993 (Fig. 2, A and B): 
more bluefish were captured by day than by night 
but daytime CPUE was more variable. The CPUE 
pattern was also seen with summer-spawned blue- 
fish (Fig. 2A). 
The number of prey captured in the 60- and 30-m 
seine hauls at each time point ranged from 1 to 1,910 
in 1993. On three out of the four dates examined, 
the relation between numbers of prey and bluefish 
(from identical seine hauls) was positive; however, 
none of these correlations were significant. 
Diel collections — gill net and surface trawl 
A total of 154 bluefish were captured in gill-net sets 
on three diel collections in 1993. Mean CPUE was 
highest during sunset and midnight collections and 
lowest during afternoon and sunrise sets (Fig. 20. A 
total of 94 bluefish were captured during surface 
trawl collections on 15-16 July 1993. Bluefish sur- 
face trawl CPUE was highest during the day (1500) 
and lowest at sunset ( 2 lOOKFig. 2D). 
Diel collections — "movement collection" 
Gill nets and beach seines captured 29 and 47 blue- 
fish on 11-12 August 1993, respectively. Gill-net 
CPUE was low during midday, increased through the 
evening to a peak at midnight (Fig. 2E), and then 
declined to zero by morning. Beach-seine CPUE was 
high during the day and low at night: the drop and 
increase in CPUE corresponded with sunset and sun- 
rise, respectively. 
Feeding period 
Time of collection had a highly significant (Kruskal- 
Wallis ANOVA, P<0.001) effect on the gut-fullness 
values of spring-spawned bluefish in 1992 and 1993 
(Figs. 3, A-F, and 4, A-E). Mean gut-fullness pat- 
terns from seine-collected bluefish in 1992 increased 
throughout the afternoon, peaked in late afternoon 
or evening, decreased throughout the night, and in- 
creased during the morning hours (Fig. 3A). 
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Figure 2 
Catch-per-unit-of-effort (CPUE) of bluefish, 
Pomatomus saltatrix, versus time of capture dur- 
ing 1992 and 1993 diel collections. (A) Mean 1992 
beach-seine CPUE (circles; ± SE) of spring- 
spawned bluefish averaged over all dates of col- 
lection ( 16-17 July, 28-29 July, 13-14 August, 26- 
27 August, and 19-20 September) and summer- 
spawned bluefish CPUE (squares) on 19-20 Septem- 
ber. (B) Mean 1993 beach-seine CPUE (± SE) of 
spring-spawned bluefish averaged over all dates of 
collection ( 7-8 July, 20-21 July, 4—5 August, and 18- 
19 August). (C) Mean 1993 gill-net CPUE averaged 
over all dates of collection (20-21 July, 4—5 August, 
and 18— 19 August). (D) Surface trawl CPUE on 15- 
16 July 1993. (E) CPUE of spring-spawned bluefish 
during the beach-seine (circles, solid line) and gill- 
net (squares, broken line) “movement collection” on 
11-12 August 1993. The time periods from sunset to 
sunrise are indicated by dark horizontal bars. 
