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Fishery Bulletin 11 6(2) 
Figure 2 
A single frame of video recorded with a lobster-trap video system 
attached to a standard lobster trap deployed off New Hampshire 
(Wallis Sands) in 2011. Note that the cover of the trap has been 
replaced with a plexiglass cover so that the features of the trap 
(kitchen, parlor, entrance heads, escape vent) and the American 
lobsters (Homarus americanus) inside the trap can be observed 
more readily. Unlike the ventless trap used in this study, the stan¬ 
dard trap contained an escape vent. 
the mean [SE] 1.27), and values ranged from 25 to 160 
mm. Lobsters caught during the 6 trials in ventless 
traps had a mean CL of 60.2 mm (SE 1.14) and, of 
these lobsters, less than 1% were at or above the lower 
legal-size limit for the American lobster inshore fishery 
(83 mm CL). None exceeded the upper legal-size limit 
for the fishery (127 mm CL). 
The 6 trials included in this study were conducted 
at a mean lobster density of 0.1 individuals/m 2 (SE 
0.02; n=8), which was consistent between trials and 
relatively high for this area and season (June to Sep¬ 
tember; Clark et al., 2015). The mean water tempera¬ 
ture across the trials was 16.1°C (SE 1.2). 
Trap video system 
The video system used in this study, lobster-trap video 
system (LTV), was modified from the original system 
developed by Jury et al. (2001). A fisheye bullet camera 
with a charge-coupled device chipset, 0.5 lux low light 
sensitivity, and 2.2-mm wide-view lens (Model PC221- 
HR, Sony Corp., Tokyo, Japan) was sealed inside an 
underwater flashlight case and mounted on the top of a 
PVC frame (Fig. 1A), 122 cm above the trap. The camera 
was connected by a waterproof cable to a water-tight 
acrylic case containing a mini digital video recorder 
(DVR) with a resolution of 640x480 lines (Model UV- 
K206, Unique Vision Technology Co., Ltd., Shenzhen, 
China) and encasing several 12V batteries (Fig. IB). 
The DVR was programmed to capture videos at a rate 
of 5 frames/s and was turned on at dawn and off at 
dusk with a digital timer to save power. Only footage 
collected during the daylight hours of day 1 and day 2 
was included in the analyses. No data were obtained 
at night because rate of trap entry does not generally 
differ between day and night at this location (Jury et 
al., 2001), and the addition of lights could have influ¬ 
enced American lobster behaviors. Digital recordings 
were stored on a Secure Digital High Capacity memory 
card (16 GB) and transferred to a computer for analyses 
after each trial. The replacement of the trap lid with 
transparent plexiglass made it possible for viewers of 
video recordings to more readily observe lobsters inside 
of the kitchen and parlor areas of traps (Fig. 2). Digital 
videos were obtained for a duration of 6.7 h (SE 1.1) on 
day 1 and 9.0 h (SE 1.6) on day 2 (Table 1). 
The dimensions of each standard and ventless trap 
are provided in Clark et al. (2015). Briefly, the wire 
