NOAA Pacific Islands Fisheries Science Center, Ecosystem Science Division Coral Reef Ecosystem Program, Rapid Ecological Assessments of Fish Belt Transect Surveys (BLT) at Coral Reef Sites across the Pacific Ocean from 2000 to 2009

Belt transects (BLT) are a non-invasive underwater-survey method that enumerates the diverse components of diurnally active shallow-water reef fish assemblages. At each Rapid Ecological Assessment survey site, BLT fish surveys are conducted along 3 consecutively-placed, 25m transect lines to quantify relatively small-bodied and abundant fishes. A pair of scuba diver-observers conducts parallel swims along the transect lines, recording size-class specific counts of all fishes encountered, to species-level where possible, within visually estimated but defined belt widths: 4 m wide for fishes > 20 cm TL (100 m2 area) on the initial swim-out, and 2 m wide for fishes < 20 cm TL (50 m2 area) on the subsequent swim back. Transect lines are typically set at depths of 10-15 m. Reef ledges and holes are visually searched. Stations are completed on all sides of the island/atoll, weather and sea conditions permitting. Raw survey data includes species level abundance estimates.