McDonald et al : Spatial and seasonal abundance of Cynoscion arenarius and C nothus off the coast of Texas 
25 
Table 1 
Sampling locations, location abbreviations, pass presence at locations (yes or no), and number of trawls (monthly and overall) 
conducted to sample sand seatrout (Cynoscion arenarius) and silver seatrout (C. nothus) in inshore and offshore waters off Texas. 
Geographic locations of the inshore and offshore trawling surveys are indicated in Figure 1. Offshore sampling sites (gulf sta- 
tions) extended 16.7 km from the state boundary of Texas. 
Location 
Abbreviation 
for location 
Pass presence 
Sample size 
(no. of trawls /month) 
Sample size 
(no. of trawls, overall 
Inshore sites 
Sabine Lake 
SL 
Yes 
10 
2760 
Galveston Bay 
GB 
Yes 
20 
4800 
East Matagorda Bay 
EMB 
No 
10 
2370 
Matagorda Bay 
MB 
Yes 
20 
4800 
San Antonio Bay 
SAB 
No 
20 
4800 
Aransas Bay 
AB 
Yes 
20 
4800 
Corpus Christi Bay 
CCB 
Yes 
20 
4800 
Upper Laguna Madre 
ULM 
No 
10 
2400 
Lower Laguna Madre 
LLM 
Yes 
10 
2400 
Offshore sites 
Gulf station A 
Gulf A 
Yes 
16 
3840 
Gulf station B 
Gulf B 
Yes 
16 
3814 
Gulf station C 
Gulf C 
Yes 
16 
3822 
Gulf station D 
Gulf'D 
Yes 
16 
3792 
Gulf station E 
Gulf E 
Yes 
16 
3829 
Sand seatrout use functioning offshore passes to fa- 
cilitate egg and larval transport from spawning areas 
(the immediate offshore) to nurseries (estuaries within 
bays) (Simmons and Hoese, 1959). However, the sea- 
sonal change in distribution of sand seatrout between 
these two locales has not been thoroughly examined. 
Furthermore, the differences in abundance of sand 
seatrout inhabiting bays with direct passes to the GOM 
and sand seatrout inhabiting bays with limited access 
to these passes have not been determined. 
The purpose of this study was to expand current in- 
formation regarding the distribution of sand and silver 
seatrout in the western GOM. To this end, two major 
objectives were identified 1) to compare the spatial and 
seasonal abundance of sand seatrout and silver seatrout 
within the immediate GOM, within the boundaries of 
Texas, and relate any distributional differences be- 
tween the two species to specific hydrological variables 
(i.e., temperature, salinity, depth) and 2) to investigate 
the spatial and seasonal abundance of sand seatrout 
between the immediate offshore and the inshore areas 
(the bays) where there were direct passes to the gulf. 
Materials and methods 
Collections 
We analyzed twenty years (1987-2006) of standardized 
offshore and inshore trawling data from Texas. The 
Coastal Fisheries Division of the Texas Parks and Wild- 
life Department (CF-TPWD) conducts annual monitoring 
of five gulf areas, as well as nine inshore bay systems 
(bays) within Texas waters (Table 1, Fig. 1). All of the 
major bay systems in Texas are protected from the GOM 
by geographical features such as islands or peninsulas. 
As such, bays were designated as all waters contained 
within the area between the Texas terrestrial shoreline 
and the associated barrier island or peninsula. Some of 
these bays have access to the GOM by means of a large 
navigable pass or cut directly through the geographical 
barrier, whereas other bays have limited access because 
of their distance from the gulf or to the navigational 
barrier presented by islands (Table 1). Gulf areas were 
those areas immediately offshore (outside the geographi- 
cal barriers) and each was situated around major passes 
and extended 16.7 km from shore. Sampling by trawling 
was divided between the first half of the month (days 
1-15) and the second half of the month (days 16- end of 
month) throughout all years. Sampling locations for gulf 
areas and bays were chosen randomly from a matrix of 
1.85-km square grids. Grids were not sampled more than 
once a month. All samples were taken during daylight 
hours when both species are susceptible to trawling 
(Shlossman and Chittenden, 1981; DeVries and Chit- 
tenden, 1982). 
Trawling was conducted with a 5.7-m otter trawl with 
38-mm nylon multifilament mesh, for both locations 
(gulf areas and major bays). Trawls were towed at the 
bottom parallel to the fathom curve at a speed of 4.83 
km/hr for ten minutes. Abundance was determined 
for all trawls as individuals collected per hour (ind. 
