30 
Fishery Bulletin 107(1 ) 
A B c D E 
Gulf areas 
Figure 4 
Differences in annual mean abundance (individu- 
als collected/hr, mean ±standard error), averaged 
over twenty years of trawl data (1987-2006), of sand 
seatrout ( Cynoscion arenarius) and silver seatrout 
(C. nothus) collected offshore within sampling areas 
of the Gulf of Mexico (A-E). 
Lower Laguna Madre (Fig. 10). There was a signifi- 
cant seasonal difference (P<0.0001) among bays with 
passes; abundance was greater in summer (7.6 ±1.5) 
than in spring (5.3 ±1.0) and fall (4.1 ±0.8). No sig- 
nificant interactive effects were reported for bays with 
direct passes and seasons (P=0.3337), and this result 
was due to parallel seasonal patterns among the bays. 
Abundance of sand seatrout was highest for inshore 
areas from Corpus Christi Bay north, for all seasons 
(Fig. 11). 
Discussion 
Distribution between species offshore 
Evidence from this study established a significantly 
lower concentration of sand seatrout than that of silver 
seatrout within 16.7 km of the immediate GOM, within 
the boundaries of Texas. Miller (1965) and Chittenden 
and McEachran (1976) also recorded a lower abundance 
of sand seatrout than silver seatrout, but they did not 
investigate the cause. The lower abundance of sand seat- 
rout than silver seatrout is most likely due to differences 
in their life histories and environmental preferences. 
Sand seatrout use both the offshore and inshore bays 
in contrast to silver seatrout which use the offshore 
throughout their lives (Shlossman and Chittenden, 1981; 
DeVries and Chittenden, 1982). Sand seatrout primar- 
ily use these estuaries during early life stages, most 
probably because of the relatively sensitive tolerances 
of juveniles to salinity. In contrast, silver seatrout have 
a much higher salinity tolerance and are more likely to 
be abundant off the coast of Texas where salinities are 
160 ■ 
140 • 
120 • 
100 ■ 
80 ■ 
60 
40 ■ 
20 ■ 
0 
160 ■ 
140 
120 
100 
80 
60 
40 ■ 
20 
0 ■ 
160 
140 
120 ■ 
100 
80 
60 
40 
20 
0 
160 
140 
120 
100 
80 
60 
40 
20 
0 
Sand seatrout 
Silver seatrout 
Fall 
ii_i 
Winter 
I Li 
Jl 
Spring 
Summer 
in ill kn 
I i i r 
A B C D E 
Gulf areas 
Figure 5 
Differences in seasonal mean abundance (in- 
dividuals collected/hr, mean ±standard error), 
averaged over twenty years of trawl data (1987- 
2006), for sand seatrout ( Cynoscion arenarius) 
(black bars) and silver seatrout (C. nothus ) 
(gray bars) in sampling areas of the Gulf of 
Mexico (A-E). 
higher than off the coasts of Louisiana or Mississippi, 
where salinities are reduced by the productive Missis- 
sippi and Atchafalaya rivers (Dinnel and Wiseman, 
1986). 
The offshore abundance of sand seatrout was lower 
than that of silver seatrout for every season other than 
summer. In the summer season, offshore silver seatrout 
