28 
Fishery Bulletin 107(1 ) 
Figure 2 
Differences in seasonal mean abundances (indi- 
viduals collected/hr, mean ±standard error), 
averaged over twenty years of trawl data (1987- 
2006), for (A) a comparison of sand seatrout 
( Cynoscion arenarius) collected off the coast of 
Texas (offshore) and silver seatrout (C. nothus ) 
collected offshore, and (B) a comparison of sand 
seatrout collected inshore (combined major bays) 
and offshore (combined Gulf of Mexico sampling 
areas), and (C) a comparison of sand seatrout 
collected inshore between bays with direct passes 
to the gulf and sand seatrout collected in bays 
without direct access to the gulf. 
did not warrant further investigation for the primary 
objectives of this study. When comparing species across 
gulf areas, we found significant differences in species 
abundance across seasons. Sand seatrout appear to be in 
their highest abundance along the upper coast, whereas 
silver seatrout are found primarily in the middle coast, 
especially in gulf areas C and D (Figs. 1 and 5). 
Water depths between our offshore sampling areas 
increased from north to south. Water depths (range, 
mean depth ±standard deviation f SD] ) among gulf ar- 
eas were as follows: gulf area A (1.2-12.8, 7.6 ±2.8), 
gulf area B (0.9-18.0, 10.5 ±3.4), gulf area C (1.2-26.5, 
14.9 ±4.8), gulf area D (0.4-23.8, 15.2 ±4.7), and gulf 
area E (2.4—30.0, 18.6 ±5.2). Within gulf areas, silver 
seatrout were more abundant at deeper water depths, 
and this trend was particularly strong during the fall 
season in gulf areas A, C, and D (P<0.05) and dur- 
ing the winter season in gulf areas of A-D (PcO.Ol). 
In contrast, sand seatrout abundance was inversely 
related to water depth within these gulf areas (Fig. 6). 
However, sand seatrout abundance was inversely related 
to water depth among gulf areas (r=-0.61, P<0.0001) 
(Fig. 7), whereas silver seatrout abundance was not 
significantly correlated with depth among offshore areas 
(r=0.06, P=0.49). Water temperature correlation coef- 
ficients exhibited no correlation with the presence of 
sand seatrout, whereas the presence of silver seatrout 
appear to have a strong positive relationship with water 
temperature specifically for the winter season in gulf 
areas (A-D) (P<0.01) (Fig. 8C). 
Salinity between our offshore sampling areas in- 
creased from north to south. Salinity among gulf areas 
were (range, mean salinity ±SD); gulf area A (3.2-40.0, 
26.4 ±4.8), gulf area B (9.0-42.0, 29.1 ±4.6), gulf area 
C (2.4-43.0, 31.4 ±3.5), gulf area D (2.4-44.0, 32.4 
±3.4), and gulf area E (23.0-42.6, 33.6 ±2.6). Although 
there were no significant differences in abundance be- 
tween these species at different salinities locally (Fig. 
8B), salinity did appear to play a role in the broad-scale 
geographic distribution of the two species, particularly 
that of sand seatrout. Sand seatrout displayed a strong 
inverse relationship with salinity among gulf areas, 
across years (r=-0.56, P<0.0001) (Fig. 9), whereas silver 
seatrout displayed no relationship with salinity among 
gulf areas, across years (r=-0.02, P=0.8003). 
Distribution of sand seatrout inshore 
Sand seatrout were much less common inshore than 
in offshore catches. Sand seatrout abundance inshore 
(mean ±standard error of ind. collected/hr) (4.6 ±0.6) 
was significantly lower (P<0.0001) than abundance off- 
shore (15.2 ±3.3). There was also a significantly higher 
abundance (P=0.0062) of sand seatrout collected in 
both summer (10.5 ±2.4) and spring (11.6 ±4.7) seasons 
than during the fall season (7.6 ±1.9). The interactive 
effects of location and season did not reveal a signifi- 
cant effect on sand seatrout abundance (P= 0.1 192 ); this 
result was due to trends in inshore abundance among 
seasons being generally predictive of trends in offshore 
