218 
Fishery Bulletin 119(4) 
Materials and methods 
Study area 
The experiment was conducted in August 2014 and in 
July and August 2015 at the Florida Middle Grounds, on 
the West Florida Shelf in the northeastern Gulf of Mexico 
(GOM) between Cape San Blas and Tampa Bay, Florida 
(Fig. 2). The Florida Middle Grounds consist of high-relief 
outcrops of carbonate rock (relief ~2—5 m) that host diverse 
assemblages of alcyonarian corals, sponges, and macroal- 
gae (Austin and Jones, 1974; Darcy and Gutherz, 1984; 
Rezak et al., 1985; Koenig et al., 2000). The Florida Middle 
Grounds are the center of a productive snapper-grouper 
fishery of the eastern GOM and also host a diverse assem- 
blage of pelagic and demersal fishes (Pierce and 
Mahmoudi, 2001). Water clarity in summer months ranges 
between 10 and 30 m, and the depth range on the bank is 
20-40 m (Koenig et al., 2000). Sampling depths ranged 
from 20 to 35 m, and sites were selected to maximize nat- 
ural light and clear water to ensure quality photography 
and accurate fish identifications and measurements. At 
the beginning of the experiment, low-relief (1-3 m) reef 
4% 4.400'W 
sites were selected to ensure safe deployment of the sam- 
pling gear. As our ability to accurately position sampling 
gear improved with time and safe vehicle transits could be 
ensured, we deployed them on increasingly complex high- 
relief habitat (>3 m). 
Platforms and deployment 
To evaluate the response to vehicles, we deployed an array 
of 3 stationary, autonomous camera platforms (Fig. 3) that 
remained on the seafloor between 7 and 10 h at multiple 
sites. The stationary platforms consisted of the Modular 
Optical Underwater Sampling System (MOUSS) (Amin 
et al., 2017) outfitted with the following components: ste- 
reo cameras, long-baseline (LBL) sonar beacons, and bat- 
teries (hereafter referred to as MOUSS platforms). The 
MOUSS platforms were fabricated with stainless steel 
and ballasted by the weight of batteries, pressure hous- 
ings, and lead weights. Optical data were collected with 
the stereo cameras, which were capable of measuring and 
positioning objects in 3 dimensions (Amin et al., 2017). 
Cameras were mounted on a base-bar with an 80-cm 
separation between cameras, at a 10° “toe-in” angle, and 
Gulf of Mexico 
™) Florida coastline 
bathymetry (10-200 m) 
Florida Middle Grounds depths (m) 
~ -52.3 
_ -42.8 
© -33.3 
Hi -23.8 
® UHSI stations 
84°7.200'W 
Figure 2 
Bathymetric map of the study area in the Florida Middle Grounds, on the West Florida Shelf in the Gulf of Mexico, 
where mobile survey vehicles and stationary camera systems were deployed to assess changes in abundance 
of reef fish taxa in response to the passage of vehicles in August 2014 and in July and August 2015. Sampling 
stations (gray circles) of the Untrawlable Habitat Strategic Initiative (UHSI) were focused on ridge habitats. 
