161 
National Marine 
Spencer F. Baird f ' V 
Fisheries Service 
Fishery Bulletin 
First U S. Commissioner YV 
NOAA 
a* established in 1881 
of Fisheries and founder 
of Fishery Bulletin HW 
Underwater video surveillance of American lobsters 
[Homarus americanus) to understand saturation 
levels in lobster traps 
Department of Biological Sciences and 
School of Marine Sciences and Ocean Engineering 
University of New Hampshire 
46 College Road 
Durham, New Hampshire 03824 
Program in Fisheries and Aquatic Sciences 
School of Forest Resources and Conservation 
University of Florida 
7922 NW 71 s ' Street 
Gainesville, Florida 32653 
Present address for contact author: The Elizabeth Moore International Center for Coral Reef 
Research & Restoration 
Mote Marine Laboratory 
24244 Overseas Highway 
Summerland Key, Florida 33042 
Department of Biology 
Saint Joseph's College 
278 Whites Bridge Road 
Standish, Maine 04084 
Maine Coastal Ecology Center 
Wells National Estuarine Research Reserve 
342 Laudholm Farm Road 
Wells, Maine 04090 
Abstract— Estimates of abundance 
of the American lobster ( Homa¬ 
rus americanus ) are often based on 
catch data and are, therefore, poten¬ 
tially influenced by trap saturation 
(a plateau in catch levels over time). 
Although aspects of trap saturation 
in standard lobster traps have been 
investigated, less is known about 
the process of saturation in vent¬ 
less traps that are currently used 
for stock assessments. Our goal was 
to investigate the possible mecha¬ 
nisms leading to trap saturation 
in ventless and standard lobster 
traps, by using in situ time-lapse 
video surveillance. The dynamics of 
saturation in standard traps were 
difficult to assess in this study be¬ 
cause entry and escape rates were 
similar throughout each trial, under 
the conditions tested; therefore, few 
lobsters accumulated in the stan¬ 
dard traps. In contrast, few lobsters 
escaped from ventless traps used 
under the same conditions. Lobsters 
consistently accumulated in ventless 
traps during the first day of fishing, 
and then the catch plateaued on the 
second day as fewer lobsters entered 
those traps. On the second day of 
soaking, catch apparently reached 
a dynamic equilibrium in which the 
rate of entry declined to the point 
where it was equal to the rate of 
escape. 
Manuscript submitted 22 May 2017. 
Manuscript accepted 19 January 2018. 
Fish. Bull. 116:161-170 (2018). 
Online publication date: 13 February 2018. 
doi: 10.7755/FB.116.2.5 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Abigail S. Clark (contact author ) 1,2 
Steven H. Jury 3 
Jason S. Goldstein 1,4 
Thomas G. Langley 1 
Winsor H. Watson III 1 
Email address for contact author: aclark@mote.org 
Effective monitoring is important 
for successful management of fish 
and shellfish populations, especially 
given the impacts of overfishing and 
a changing ocean climate (Brand- 
er, 2010). Catch per unit of effort 
(CPUE) is currently the most widely 
used indicator of abundance for the 
American lobster (Homarus ameri¬ 
canus), which is the focus of one of 
the most valuable fisheries in the 
United States and Canada. Further¬ 
more, CPUE is an important metric 
for stock assessments. However, ow¬ 
ing to concerns that catch in traps 
may not provide an accurate index 
of actual populations under certain 
conditions (Watson and Jury, 2013), 
several U.S. states (Maine, New 
Hampshire, Rhode Island, and Mas¬ 
sachusetts) now conduct annual sur¬ 
veys with ventless traps to better es¬ 
timate relative abundances of Ameri¬ 
can lobsters (MDMR 1 ; MADMF 2 ). 
Determining indicators and ref¬ 
erence points for American lobster 
abundance, particularly those of pre¬ 
recruits, remains an ongoing chal¬ 
lenge (Caddy, 2004; Steneck, 2006). 
Jury et al. (2001) showed that ap¬ 
proximately 94% of American lob¬ 
sters that entered standard traps 
ultimately escaped and, of those that 
escaped, 28% exited through the es- 
1 MDMR (Maine Department of Marine 
Resources). 2011. Maine Department 
of Marine Resources 2011-2012 research 
plan, 27 p. [Available from website, ac¬ 
cessed January 2017.] 
2 MADMF (Massachusetts Division of 
Marine Fisheries). 2014. Massachu¬ 
setts Division of Marine Fisheries 2014 
annual report. [Available from website, 
accessed January 2017.] 
