McDonald et al.: Spatial and seasonal abundance of Cynoscion arenorius and C. nothus off the coast of Texas 
29 
Sand seatrout 
(inshore) 
260 - 
130 - 
260 “ 
1 30 — 
260 
1 30 — 
260 
130 - 
260 
130 - 
260 ' 
130 “ 
260 ' 
1 30 — 
260 - 
130 “ 
260 ' 
130 - 
260 - 
130 - 
260 ' 
130 ' 
260 ' 
130 - 
Sand seatrout 
(offshore) 
-nllFlnllnr. 
January 
February 
March 
April 
May 
June 
July 
August 
September 
October 
^UinnnnrUTnjlllJllk-., 
November 
December 
1000- 
500 - 
1000 - 
500 
1000 ' 
500 “ 
1000-' 
500 
1000-' 
500 - 
1000' 
500 - 
1000 - 
500 - 
1000“ 
500 - 
1000 “' 
500 - 
1000-- 
500 - 
1000 -' 
500 - 
1000“ 
500 - 
° s ° 7 °o 7 s 0 % % % Ss 0 *0 0 
Silver seatrout 
(offshore) 
niS,S 
January 
February 
March 
April 
May 
June 
July 
August 
September 
October 
November 
December 
, -i-. 
o So 7o 0 7 S 0 ?0 0 ?S 0 3 0 0 3s 0 '>O cl 
Size class (mm, TL) 
Figure 3 
Monthly length-frequency histograms (averaged over twenty years of trawl data 
(1987-2006)) for combined major bays (inshore) in the Gulf of Mexico for sand 
seatrout (Cynoscion arenarius), combined gulf sampling areas (offshore) for sand 
seatrout, and for combined offshore sampling areas for silver seatrout ( C . nothus), 
by 10-mm total length (TL) size classes. 
abundance, although overall abundance remained higher 
offshore (Fig. 2A). The length-frequency histograms 
further illustrated differences in abundance among loca- 
tions (Fig. 3). Sand seatrout collected inshore appeared 
to decrease in abundance after August, whereas off- 
shore sand seatrout began to decrease in abundance 
after spring, specifically after July. Additionally, clear 
bimodal peaks in abundance were evident for May in 
both inshore and offshore areas, reflecting the bimodal 
spring and late-summer+fall spawning times of sand 
seatrout (Shlossman and Chittenden, 1981). 
Sand seatrout were significantly higher (P<0.0001) 
in abundance in major bays with passes (mean ±SE) 
(5.9 ±0.8) than in bays without direct passes (1.4 ±0.4) 
(Table 2). There was also significant seasonal differ- 
ence (P=0.0003) inshore; abundance was higher in the 
summer (4.9 ±1.3) than in spring (3.2 ±0.9) and fall 
(2.8 ±0.8). The interactive effects of pass presence and 
season were not significant (P=0.1255) (Fig. 2B). How- 
ever, sand seatrout differed significantly in abundance 
among bays with passes (P<0.0001) (Table 2), and all 
bays were significantly greater in abundance than the 
