380 
Fishery Bulletin 117(4) 
Table 3 
Results of the paired t-tests and randomization tests used to compare catch per unit of effort (CPUE), weight divided by tow time, 
between the control gear and 5 experimental (Exp.) gears tested in 2015 in Pamlico Sound, North Carolina. Some of the gears had 
trawl efficiency devices (TEDs) with reduced bar spacing, and bycatch reduction devices (BRDs) included a composite panel, the 
Ricky BRD, and a federal fisheye. Mean values of CPUE are reported in kilograms. n=number of tows. 
Gear 
Taxonomic 
group 
n 
Control 
Exp. 
t-test 
Control 
Exp. 
Randomization 
Mean 
Mean 
Change 
(%) 
P-value 
rt 
Mean 
Mean 
Change 
(%) 
P-value 
Composite panel 
Finfish 
44 
178.1 
132.1 
-25.83 
<0.001 
60 
177.3 
128.4 
-27.60 
<0.001 
Shrimp 
44 
64.3 
63.9 
-0.65 
0.754 
60 
67.3 
65.2 
-3.13 
0.776 
Reduced-bar TED 
Finfish 
16 
107.3 
70.0 
-16.18 
0.029 
19 
112.8 
89.8 
-20.40 
0.217 
Shrimp 
16 
49.6 
46.0 
-7.35 
0.078 
19 
48.2 
45.5 
-5.63 
0.739 
Reduced-bar TED + square mesh panel + 
Finfish 
40 
104.8 
78.2 
-25.34 
<0.001 
51 
102.3 
74.1 
-27.50 
0.007 
4.76-cm codend 
Shrimp 
40 
65.7 
64.4 
-1.94 
0.309 
51 
67.3 
65.2 
-3.04 
0.775 
Ricky BRD 
Finfish 
10 
110.6 
103.3 
-6.61 
0.503 
15 
100.0 
95.5 
-4.55 
0.793 
Shrimp 
10 
35.3 
31.8 
-9.87 
0.449 
15 
35.4 
33.3 
-6.06 
0.728 
Double federal fisheyes + 4.76-cm codend 
Finfish 
25 
90.0 
53.3 
-40.81 
<0.001 
32 
88.3 
52.9 
-40.10 
<0.001 
Shrimp 
25 
61.3 
61.9 
1.00 
0.778 
32 
60.6 
61.9 
2.16 
0.862 
Table 4 
Results of the paired t-tests and randomization tests used to compare catch per unit of effort (CPUE), weight divided by tow time, 
between the control gear and 4 experimental (Exp.) gears tested in 2016 in Pamlico Sound, North Carolina. One of the gears had a trawl 
efficiency device (TED) with reduced bar spacing, and bycatch reduction devices included the Virgil Potter and federal fisheye. Mean 
values of CPUE are reported in kilograms. Values for invertebrates are for all non-commercial shrimp invertebrates. n=number of tows. 
Gear 
Taxonomic 
group 
n 
Control 
Exp. 
t-test 
n 
Control 
Exp. 
Randomization 
Mean 
Mean 
Change 
(%) 
P-value 
Mean 
Mean 
Change 
(%) 
P-value 
Virgil Potter 
Finfish 
30 
146.3 
106.9 
-26.92 
<0.001 
33 
149.4 
106.9 
-28.50 
0.005 
Shrimp 
30 
62.6 
68.8 
9.92 
0.050 
33 
61.8 
67.0 
8.51 
0.696 
Invertebrates 
10 
3.3 
2.7 
-18.79 
0.384 
33 
1.0 
0.8 
-18.80 
0.681 
Elasmobranchs 
7 
5.3 
5.9 
11.11 
0.589 
33 
1.1 
1.2 
11.10 
0.912 
Double federal fisheye + 
Finfish 
6 
201.5 
86.3 
-57.19 
0.001 
23 
164.5 
75.6 
-54.00 
<0.001 
4.45-cm codend 
Shrimp 
6 
23.0 
20.2 
-12.11 
0.215 
23 
28.1 
23.6 
-16.20 
0.280 
Invertebrates 
6 
7.2 
6.1 
-15.67 
0.081 
23 
5.4 
5.1 
-4.85 
0.833 
Elasmobranchs 
6 
1.8 
2.6 
45.79 
0.509 
23 
2.1 
2.5 
18.80 
0.573 
Reduced-bar TED + double fed- 
Finfish 
30 
115.4 
63.6 
-44.91 
<0.001 
30 
115.4 
63.6 
-44.90 
0.007 
eral fisheye + 4.45-cm codend 
Shrimp 
30 
27.0 
25.7 
-4.85 
0.435 
30 
27.0 
25.7 
-4.85 
0.706 
Invertebrates 
30 
2.1 
1.8 
-13.26 
0.418 
30 
2.1 
1.8 
-13.30 
0.601 
Elasmobranchs 
27 
1.8 
1.4 
-18.62 
0.404 
30 
1.6 
1.3 
-18.60 
0.568 
Virgil Potter + 4.45-cm codend 
Finfish 
22 
189.1 
107.4 
-43.20 
<0.001 
25 
172 
96.1 
-44.30 
0.001 
Shrimp 
22 
33.2 
31.3 
-5.46 
0.055 
25 
31.3 
29.5 
-5.78 
0.691 
double state fisheyes, and a 4.13-cm codend was tested 
in autumn; however, the observed catches were relatively 
small. 
Test comparison 
A comparison of the results from the paired t-tests and 
randomization tests (relative to the results of each other 
and to the raw data as collected) is provided in Tables 3-5. 
In general, both tests produced similar results. A paired 
t-test detected a significant decrease in finfish CPUE for 
the reduced-bar TED (tested in 2015) and the reduced-bar 
TED with a 4.13-cm codend (tested in 2017), whereas the 
results of the randomization tests indicate no significant 
difference in finfish bycatch between these gears (Tables 3 
and 5). Additionally, a paired t-test detected a significant 
increase in shrimp catch for the Virgil Potter gear (tested 
in 2016), but in a randomization test, no significant change 
