RVC Methodology

Reef fish visual census (RVC) data are collected using a stationary point sampling technique which utilizes standard visual sampling methods. This year we will try to complete censuses at 75 stratified random sites from the north and west side of the island (red dots on map). At each point two divers record all fish species observed in five minutes within an imaginary cylinder extending from the surface to the bottom within a radius of 7.5 meters (24.6 feet) from the observer. After recording species for five minutes, divers next record quantitative data for these species; estimated number of individuals and the minimum, maximum, and mean estimated length. New species to the sample, which include the rare or cryptic species, observed after the initial 5 minutes are also recorded, along with estimates of length for selected species, to expand the species list composition. An underwater digital camera is used to record unknown species, as well as document fish assemblages.
Dave McClellan