490 
Fishery Bulletin 95(3), 1997 
a> 
O 
c 
03 
■O 
_Q 
03 
16 
£ 
03 
03 
■D 
C 
03 
CD 
160 
120 
80 
40 
10 15 
Temperature 
160 
120 
.2 80 
40 
20 
120 
80 
40 
D A M .. . V ^ 
0 45 90 135 180 225 270 315 360 
Wind direction 
160 
120 
80 
40 
2 4 6 8 10 12 14 
Wind speed (m/sec) 
i l 
: I 
i I 
160 
120 
80 
40 
0.2 0.4 06 0.8 
Current speed (m/sec) 
160 
120 
80 
40 
1 2 3 4 5 6 7 8 9 10 11 12 1st 
Hours since sunset 
FULL Lsl NEW 
Moon phase 
Environmental factors 
Figure 9 
Abundance of B. tyrannus collected during 138 sampling nights versus nine environmental factors. Wind direction 
is direction wind is coming from. Vertical axis is abundance (number larvae per 100 m 3 ). 
sion analysis and the principal-component analysis 
suggested that unknown factors on a scale larger 
than the locally measured environmental conditions 
are probably more important in causing peaks in 
abundance of the immigrating larvae. Originating 
from wide-spread spawning sites during the fall-win- 
ter period, larvae of different spawning cohorts ar- 
rive near the inlet from many possible transport 
routes. The most likely factor is onshore displace- 
ment of warm Gulf Stream filaments containing 
patches of larvae (Stegmann and Yoder, 1996). Once 
under the influence of tidal exchange at the inlet, 
patches of larvae merge as they ingress the estuary. 
Variables including temperature, salinity, turbu- 
lence, turbidity, odors, and currents differentially 
affect survival or active transport behavior into the 
estuary (Boehlert and Mundy, 1988). Larval behav- 
ior may have contributed to the fact that some spe- 
cies were more abundant in catches made later in 
the night (e.g. L. rhomboides, L. xanthurus, M. 
cephalus, and P. dentatus), acting to disperse larvae 
into the water column from the edges and bottom, 
thus making them more vulnerable to the sampling 
gear. 
