Colura and Bumguardner: Effect of the salt-box catch-bycatch separation procedure, as used by the Texas shrimp industry 
405 
Table 7 
Spearman correlation coefficients (r ) and probability (P) that the coefficient values were greater than 0, of variables that dem- 
onstrated relationships with mortality rate (M), initial percent survival, and final percent survival for bycatch (all species) and 
Atlantic croaker. Samples were collected from the catch of Texas bay shrimpers and separated with or without a salt-box. A space 
indicates the probability that the variables r s value was greater then 0 was >0.05. 
Variable 
M 
Initial survival 
Final 
survival 
r s 
P 
P 
r s 
P 
Bycatch 
separation time 
0.638 
<0.001 
-0.586 
0.001 
-0.749 
<0.001 
trawling time 
0.650 
<0.001 
-0.414 
0.023 
-0.665 
<0.001 
bay temperature 
-0.459 
0.011 
bay anchovy 
0.477 
0.008 
Atlantic croaker 
0.526 
0.003 
-0.391 
0.033 
gulf menhaden 
0.445 
0.014 
-0.461 
0.010 
sand seatrout 
0.458 
0.011 
-0.564 
0.001 
pinfish 
-0.434 
0.017 
bighead searobin 
-0.368 
0.046 
gafftopsail catfish 
-0.398 
0.029 
bay whiff 
0.379 
0.039 
Atlantic cutlassfish 
-0.373 
0.042 
salt-box 
0.488 
0.006 
Atlantic croaker 
separation time 
0.637 
0.008 
0.459 
0.016 
least puffer 
0.994 
<0.001 
hardhead catfish 
-0.592 
0.001 
blue crab 
-0.463 
0.015 
brown shrimp 
-0.566 
0.002 
harvestfish 
0.401 
0.038 
0.400 
0.038 
Atlantic brief squid 
-0.833 
0.039 
salt-box 
-0.629 
0.004 
Table 8 
Independent variables that entered stepwise multiple regression models describing bycatch (all species), initial percent survival, 
final percent survival, and mortality rate (M), and Atlantic croaker M resulting from Texas bay shrimpers separating them from 
shrimp with or without the aid of a salt-box. Included are y-intercepts±SE, coefficients±SE of the selected independent variables, 
partial r 2 of each variable in parenthesis, and model r 2 . A space indicates the variable did not enter the model. 
Dependent 
variable 
Independent variable 
y-intercept 
Separation time 
Trawl time 
Bay temperature 
Salt-box 
Model R 2 
Bycatch 
initial survival 
217.4 ±65.3 
-120.5 ±21.8 (0.52) 
0.52 
final survival 
60.0 ±6.9 
-20.2 ±4.1 (0.48) 
-15.5 ±5.8 (0.11) 
0.59 
M 
2.3 ±1.2 
5.1 ±0.4 (0.79) 
-0.3 ±0.1 (0.03) 
-0.1 ±0.04 (0.03) 
0.85 
Atlantic croaker 
final survival 
51.2 ±10.1 
61.9 ±27.0 (0.11) 
-31.22 ±10.0(0.38) 
0.49 
any bycatch species. The initial survival (r s =0.459) and M 
(r s =0.637) of Atlantic croaker were related to catch separa- 
tion time. Atlantic croaker final survival (r s =-0.629) was 
negatively correlated to use of a salt-box. 
Stepwise multiple regression identified four variables, 
which explained most of the variation associated with the 
three measurements (Table 8). Catch separation time (total 
time that bycatch was on the vessel), trawling time, and 
