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Pacific Reef Assessment and Monitoring Program: Rapid Ecological Assessments of Fish Belt Transect Surveys (BLT) at Coral Reef Sites across the Pacific Ocean from 2000 to 2009

Published by Pacific Islands Fisheries Science Center | National Oceanic and Atmospheric Administration, Department of Commerce | Catalog Last Checked: May 10, 2026 at 05:53 AM | Dataset Last Updated: January 01, 2017 at 12:00 AM
Belt transects (BLT) is one of the non-invasive underwater-survey methods to enumerate the diverse components of diurnally active shallow-water reef fish assemblages. At each REA survey sites, 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. Transects 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 included species level abundance estimates. Reef fish and benthic estimate data collected during BLT surveys can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

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