214 
Fishery Bulletin 117(3) 
the surveys conducted on day 1 because handling often 
leads to an escape response or other aberrant behavior, 
which might have caused them to leave the area (senior 
author, personal observ.). After the trap had been deployed 
for 24 h, the dive survey described above was repeated 
to determine if the density of lobsters around the trap 
had changed. This experiment was repeated on 5 differ¬ 
ent occasions. A Wilcoxon matched-pairs signed rank test 
(n= 5) was used to compare the density of lobsters present 
before and after the trap had soaked for 24 h. 
Influence of lobsters in a trap on the entry 
of additional lobsters 
American lobsters in a ventless trap may deter the entry of 
additional lobsters and thus reduce the rate of entry, lead¬ 
ing to a plateau in catch (trap saturation). We conducted 
experiments with soak times of 24 h and 48 h to test this 
hypothesis and we both added lobsters to a trap (pre¬ 
stocked) and removed lobsters that were captured after 
24 h from a trap, before redeploying it for another 24 h. 
Pre-stocking experiment with 24-h soak Between 1 August 
2013 and 2 October 2013, 6 different ventless traps were 
pre-stocked with all of the lobsters that were caught from 
6 other ventless traps that had been deployed for 24 h. The 
number of lobsters used for pre-stocking was a function 
of the number of lobsters initially captured; lobsters were 
transferred directly from one ventless trap to another. 
The average number of lobsters used to pre-stock traps 
was 28.6 (SD 4.2; range: 21-33). Importantly, these lob¬ 
sters had a size-frequency distribution that was typical 
for lobsters captured by ventless traps in this location. 
The lobsters used for pre-stocking were also marked, with 
a coded rubber band placed on the carpus of each of their 
claws (i.e., “knuckles”), so that they could be differentiated 
from any subsequently captured lobsters. We confirmed 
that the tags remained on lobsters for at least 1 week in a 
separate study conducted at the University of New Hamp¬ 
shire (UNH) Coastal Marine Laboratory (New Castle, New 
Hampshire). Pre-stocked ventless traps were provided 
with fresh bait and deployed in locations at least 0.5 km 
away from where the traps used to capture the lobsters for 
pre-stocking were fished, but in the same general fishing 
area. The pre-stocked ventless traps were then deployed 
for 24 h and catch was compared to the catch in the vent¬ 
less traps that were initially used to capture the lobsters 
used for pre-stocking. The Mann-Whitney U test was used 
for this comparison, as well as for subsequent analyses 
when catch was compared between 2 groups of traps. 
Trap emptying experiment with 48-h soak In this study, 
which was conducted between 1 August 2013 and 9 Octo¬ 
ber 2013, ventless traps (n=9) were deployed for 24 h and 
then hauled. All captured lobsters were removed, but the 
used bait in each trap was retained. The lobsters were 
then released >0.5 km from where they were captured 
to minimize the chance of subsequent recapture. These 
traps, emptied of lobsters, were redeployed with the same 
1-day-old bait for an additional 24-h soak. The catch from 
the initial 24-h deployment with fresh bait was com¬ 
pared with catch during the second 24-h soak of the same 
trap with the 1-day-old bait. The net catch for the entire 
soak time of 48 h, or the sum of the animals captured on 
day 1, plus those captured on the day 2, was also com¬ 
pared with catch from control ventless traps (n=27) that 
were deployed continuously for 48 h during the same time 
period, within the same study area. 
Loss of bait attractiveness 
Studies testing the hypothesis that bait loses at least some 
of its attractiveness over a soak were also conducted with 
traps deployed for both 24 h and 48 h. 
Bait experiment 1: 24-h-old versus fresh bait Traps {n= 33) 
were deployed for 24 h and then the used bait was removed 
and placed into different ventless traps. These traps were 
then then redeployed with the 1-day-old bait in a differ¬ 
ent location, >0.5 km away, but in the same general study 
area. Catch in the original traps, fished with fresh bait for 
24 h, was compared with catch in the traps fished with 
1-day-old bait for 24 h. 
Bait experiment 2: 48-h soak with rebait Ventless traps 
(n= 27) were deployed for 24 h and hauled, the used bait 
was removed, and then the traps were rebaited with the 
same amount of fresh bait. Lobsters in each trap were 
counted but not removed from the trap, and the traps 
were redeployed and fished for another 24 h. In a supple¬ 
mentary experiment using a ventless trap equipped with 
a LTV system (n= 7), the fresh bait was added by scuba 
divers after a soak of 24 h so that video recordings would 
not be interrupted by hauling of the trap and any lobsters 
retained by the trap up to this point would not be star¬ 
tled, potentially influencing their behavior. After an addi¬ 
tional 24-h soak with the new bait (48-h total soak time), 
the trap was hauled and the captured lobsters quantified. 
The catch for the traps that received fresh bait (/?.=27) was 
compared to the catch in control ventless traps (n=34) that 
were continuously deployed with the same bait for 48 h, in 
the same general area and during the same time period. 
We also used data from the 7 trials with the LTV sys¬ 
tem, described above, to quantify the number of lobsters 
that entered and escaped from traps during experiments 
in which scuba divers added fresh bait. In addition, the 
videos obtained allowed us to determine the total number 
of lobsters in the trap each hour (i.e., accumulated catch), 
so that the time course of saturation could be plotted. 
Bait experiment 3: leaching of amino acids This experiment 
was conducted to determine the relative rate at which 
amino acids leached out of bait over 24 h. Salted Atlan¬ 
tic herring (4 samples, each with a wet weight of 150 g) 
were put in individual bait bags, which were then placed 
into 1-L beakers containing clean artificial seawater with 
a practical salinity of 32 (Crystal Sea Marinemix, Marine 
Enterprises International, LLC, Baltimore, MD) and gently 
