A stratified random sampling design was employed to sample fish and benthic communities with a remotely operated vehicle (ROV) in the sanctuary at depths greater than 150'. A sample frame consisting of mutually-exclusive 200m X 200m grid cells was produced and overlaid on the existing benthic habitat map to exhaustively cover all habitats. Each grid cell was considered a sample unit and units were divided into eight strata. Strata were defined using benthic habitat, and location (East or West Bank). Benthic habitats include: coralline algal reef, deep reef, algal nodule, and soft bottom. Data were collected within 100m2 transects. Transects radiated from the centroid of each sample unit at a random bearing.
Once in the field, the boat captain navigated to previously selected sites and the ROV was launched. The ROV has GPS positioning so it can be deployed on a site and navigate to other sites without having to be brought back aboard the vessel. Once deployed, high resolution video cameras are continuously running. Once the station has been reached, the ROV slows to approximately 1 knot and attempts to run along a predetermined heading. If currents are too strong,the transect is run into the current to maintain stability. If the current is too strong the transect is aborted . The video is fed into the vessel and scientists take notes about fish and benthic communities as the ROV conducts the transect. Every 30 seconds the ROV slows and hovers approximately 3 m off the bottom. A digital still photograph is taken of the bottom, then the transect continues.
Fish and benthic analysis are conducted back in the lab upon the completion of the cruise.
Data were collected on the following:
1) Logistic information - date, time of survey, site code, transect bearing, depth.
2) Abundance & size - Fish were identified to the lowest possible taxon possible and the number of individuals per species is tallied in 5cm size class increments up to 35cm using visual estimation of fork length. If an individual is greater than 35cm, then an estimate of the actual fork length is recorded.