After four nights of camera operations in the Harris Point Reserve (one
night was lost due to camera malfunctioning), we have collected
Approximately twenty-five hours of video. Each night, we use the maps
Generated by sidescan sonar to select track lines that cover features
requiring video verification for interpretation. We have been very
successful at using the maps to aid operations - and can predict an
upcoming feature using the maps. In this way, we are able to prevent
catastrophes like running the camera into a rock wall (we have the
sidescan maps shown on a computer monitor, with the ship's current
position plotted on the map; as we approach a significant feature such
as a rock wall, we can bring the camera off the bottom thereby avoiding
a potential collision.) Our ability to accurately predict upcoming
features has given us confidence in our interpretation of the sidescan
maps.
In addition to "ground truthing" sidescan imagery, we are also
characterizing the habitat in the Harris Point Reserve. During
operations, a team of three scientists huddle around the video monitor
aboard McARTHUR II. One scientist calls out what she is seeing while a
second records all observations. We are documenting habitat type (rock
wall, boulder, cobble, sand, mud, etc.) relief (high, medium, low, flat)
and noting fish (rockfish, flatfish, combfish, etc) and invertebrates
(crabs, seastars, sea cucumbers, urchins, etc). These data will give us
information about the types of organisms found in the different habitats
of the Harris Point Reserve.
We are very pleased with the video operations thus far - we have had four
nights of excellent data collection with few problems. However, camera
operations are a very slow way to survey an area: in 25 hours of
operation we estimate we have covered just 0.0055 square kilometers, as
compared to the 64 square kilometers we have mapped using sidescan.
Clearly, mapping the Harris Point Reserve using a camera sled would be a
time consuming operation. However in conjunction with sidescan sonar,
it can be a very useful tool for understanding this area.

 

Sarah Fangman
Research Coordinator
Channel Islands National Marine Sanctuary