166 
Fishery Bulletin 116(2) 
Table 2 
Mean number of American lobsters entering, escaping, and surrounding each trap per hour during 6 trials in which 
ventless and standard traps were deployed for periods of 2 d off New Hampshire (Wallis Sands) during 2010-2012. 
The means and standard deviations (SD) were calculated by using data from the first 3 h of each day. 
Number of entries Number of escapes Number of lobsters 
(SD) (SD) surrounding traps (SD) 
Trial 
Trap type 
Day 1 
Day 2 
Day 1 
Day 2 
Day 1 
Day 2 
1 
Standard 
4.7 (2.1) 
0 
4.0 (2.0) 
0 
3.4 (1.9) 
3.1 (0.2) 
2 
Standard 
3.7 (2.9) 
4.0 (1.0) 
4.0 (3.6) 
3.3 (2.1) 
2.5 (0.8) 
1.6 (0.1) 
3 
Standard 
2.0 (1.7) 
2.0 
1.3 (1.5) 
1.7 (0.6) 
1.4 (0.7) 
1.5 (0.8) 
4 
Ventless 
2.7 (0.6) 
0.3 (0.6) 
1.0 (1.7) 
0 
2.2 (0.6) 
0.3 (0.1) 
5 
Ventless 
5.7 (3.1) 
1.3 (1.2) 
1.0 (1.7) 
0.7 (0.6) 
3.5 (0.1) 
0.6 (0.4) 
6 
Ventless 
5.7 (0.6) 
0 
0 
0 
3.8 (1.7) 
0.2 (0.1) 
n 
o 
a> 
n 
E 
3 
C 
16 
,o 
60 -I 
50 - 
40 - 
30 - 
20 ■ 
10 ■ 
Ventless 
a Surrounding 
a Entries 
■ Escapes 
l 
60 
50 ■ 
M 
40 • 
II 
H 
30 • 
20 ■ 
10 ■ 
0 ■ 
Standard 
Day 1 Day 2 
Figure 4 
Number of American lobsters (Homarus americanus) observed 
surrounding, entering, and escaping ventless traps (n= 3) and 
standard traps (n= 3) over the first 3-h period of video footage 
recorded on day 1 and day 2 of deployments off New Hamp¬ 
shire (Wallis Sands) during 2010-2012. 
To determine whether American lobsters inside the 
trap inhibited the entry of approaching lobsters, half¬ 
entries, defined as any instance in which a lobster 
made contact with the mesh funnel of the kitchen en¬ 
trance but did not fully enter the kitchen (Jury et al., 
2001), were quantified. Our working hypothesis was 
that if the lobsters inside the trap inhibited other lob¬ 
sters from entering the trap on day 2, the number 
of half-entries should be higher on day 2 than on 
day 1. Because we expected more lobsters to have 
accumulated inside the ventless traps by day 2, 
we also expected more agonistic interactions be¬ 
tween entering lobsters and the lobsters already 
in the trap and, therefore, more half-entries to¬ 
ward the end of each trial. After calculating the 
total number of half-entries, we used the Mann- 
Whitney £7 test to determine whether differences 
existed over time and between trap types. 
Results 
Movements in, and around, standard and ventless 
traps 
A similar number of American lobsters en¬ 
tered ventless traps and standard traps on day 
1 (Figs. 3 and 4, Table 2; Mann-Whitney £7=7, 
P>0.05). There was also no significant difference 
in the number of lobsters surrounding each trap 
(Mann-Whitney £7=7, P>0.05). However, signifi¬ 
cantly more lobsters escaped from standard traps 
than from ventless traps (Mann-Whitney £7=0, 
P<0.05). On day 2, a similar number of lobsters 
entered (Mann-Whitney [7=2.5, P>G.05) and es¬ 
caped (Mann-Whitney £7=2, P> 0.05) each respec¬ 
tive trap type. For example, on day 2, 5 lobsters 
entered ventless traps and 2 escaped. Even so, 
there were fewer lobsters surrounding ventless 
traps than standard traps (Mann-Whitney £7=0, 
P< 0.05). 
Fewer lobsters entered ventless traps on day 2 than 
on day 1 (Figs. 3 and 4, Table 2; Mann-Whitney £7=9, 
P<0.05). Although there was no difference in the num¬ 
ber of lobsters escaping from ventless traps on day 
1 versus day 2 (Mann-Whitney £7=7, P>0.05), signifi¬ 
cantly fewer lobsters surrounded the ventless traps 
on day 2 than on day 1 (Mann-Whitney £7=9, P<0.05). 
