Merritt et al.: BotCam: a baited camera system for nonextractive monitoring of bottomfish species 
57 
(Randall, 2007). Most of these species are long-lived, 
slow-growing, and are assumed to have a low annual 
natural mortality rate and limited reproductive capacity 
(Haight et al., 1993a). These characteristics make these 
bottomfish stocks especially susceptible to overfishing 
and habitat destruction (Ralston et al. 1 ). 
The Hawaiian bottomfish fishing is primarily con- 
ducted by jigging hooks and lines on motorized reels. 
All of the deep 7 species eat a variety of fish and in- 
vertebrate species opportunistically. For example, E. 
coruscans are known to feed on species within the water 
column near the bottom, whereas E. carbunculus targets 
species on the bottom. All target species are caught 
by using both fish, such as mackerel ( Decapterus spp.) 
and invertebrates (such as squid) as bait. Fishing ves- 
sels that anchor will often use a palu bag containing a 
mixture of baits. 
Although the entire range of depths used by the 
Hawai'i deepwater bottomfish assemblage has not been 
determined, the Western Pacific Regional Fishery Man- 
agement Council (WPRFMC) has defined the deepwater 
bottomfish essential fish habitat as all depths between 
100 and 400 m, and adult habitat areas of particular 
concern as slopes and escarpments between 40 and 280 
m depth (WPRFMC, 1998). Low light levels at these 
depths complicate the use of cameras. However, sur- 
veys with submersibles and remotely operated vehicles 
(ROVs) indicate that ambient lighting is preferable to 
artificial area lights or strobes because the artificial 
lights may repel or attract target species (Ralston et 
al., 1986; Ryer et al., 2009). 
To address the need for a nonextractive, fishery-in- 
dependent method for monitoring Hawaiian bottomfish 
stocks, a baited stereo-video camera system (BotCam) 
has been developed by the National Oceanic and Atmo- 
spheric Administration’s Pacific Islands Fisheries Sci- 
ence Center (PIFSC) in collaboration with the Hawai'i 
Undersea Research Laboratory. BotCam is designed to 
survey the distribution, relative abundance, and size 
composition of bottomfish, and associated biological and 
physical characteristics of their habitat. 
A pilot study was designed to test BotCam as a tool 
in making stock assessments. The main purpose of the 
study was to determine whether, from an operational 
perspective, BotCam can consistently and reliably col- 
lect the same types of data collected by other baited ste- 
reo-video camera systems, as reported in the literature, 
on the commercially important Hawaiian bottomfishes. 
More specifically, we asked if the system could obtain 
a metric of relative abundance, accurate information on 
habitat associations, and a length-frequency distribu- 
tion for fish of a given fishery. 
1 Ralston, S., S. Cox, M. Labelle, and C. Mees. 2004. Western 
Pacific Regional Fishery Management Council bottomfish 
stock assessment workshop final panel report; January 13-16, 
20 p. [Available from Western Pacific Fishery Manage- 
ment Council, 11643 Bishop Street, Suite 1400, Honolulu, 
HI 96813.] 
Materials and methods 
Baited stereo-video camera system 
BotCam was designed as a fully autonomous baited 
stereo-video camera system (Merritt, 2005). Most of 
the components are housed in an aluminum frame (1.2 
m wide x 0.5 m deep x 0.45 m tall) designed to protect 
the cameras and maintain fixed camera positions to 
one another for accurate length measurements (Fig. 1). 
The system consists of two ultralow-light video cameras 
(Monochrome Navigator, Remote Ocean Systems, San 
Diego, CA), the video capture electronics and system con- 
troller (Viperfish Deep, Deep Development Corporation, 
Sumas, WA), a temperature and pressure recorder (SBE 
39TP, Seabird Electronics Inc., Bellvue, WA), a custom- 
built battery pack and relay used to trigger a delayed 
bait release-system (BWR, Sexton Photographies LLC, 
Salem, OR), and syntactic foam blocks for positive buoy- 
ancy (Flotation Technologies, Biddeford, ME). The frame 
also allows for the attachment of oceanographic instru- 
ments such as current meters, temperature and depth 
recorders, and hydrophones. The system is moored to the 
bottom by anchor weights attached to an anchor line and 
is designed to float above the bottom and to record video 
by pointing horizontally down-current with a nominal 
downward angle of 15°. This orientation improves the 
view of the benthic habitat without sacrificing the field 
of view. Each camera provides an 80° diagonal field of 
view in water. Because of the depth of targeted deploy- 
ments, motions of the floating system are not affected 
by surface waves and the platform moves only by means 
of the currents, which are generally driven by tides, 
and are therefore stable on the order of several min- 
utes. BotCam does often rotate and change the field of 
view relative to the substratum over the duration of a 
deployment. This floating design was chosen to address 
a couple of concerns. First, the target species are known 
to school in the water column several meters above the 
bottom. Second, the habitat of these target species is 
found on extremely steep and rocky slopes and setting 
a system directly on the bottom would be problematic 
for both the deployment and recovery of the system. An 
extension arm attached to the frame can carry both a 
stereo-video synchronizing (SVS) device and a bait can- 
ister or bag in view of the cameras (Fig. 1). The SVS, a 
grid of lights that flash in rapid succession, was custom 
made by Sexton Photographies LLC (similar to a system 
used by Harvey and Shortis (1996)) and allows two 
video streams to be synchronized by time for accurate 
stereo-video measurements. The lights flash at 30 Hz for 
1 second every minute and no reaction to the lights has 
been observed by any of the target species. The first of 
two baiting modes involves simply attaching a bait bag 
or trap feeder to the extension arm. The second method 
involves the use of a 1.7-L Niskin bottle to hold bait 
sealed inside; at a predetermined time the bottle opens, 
exposing the bait. 
An acoustic release (AR701, Ixsea, Boston, MA) was 
placed between the bottom of the frame and a set of two 
