The Government of Guam's Comprehensive Long-term Monitoring at Permanent Sites in Guam project, also known as the Guam Long-term Coral Reef Monitoring Program (GLTMP), is a NOAA-funded project currently coordinated through the University of Guam Marine Laboratory. The program involves the regular, intensive collection of data for a suite of coral reef ecosystem health parameters at high priority reef areas (HPRAs) around Guam, as well as critical support for coral bleaching response and other activities carried out by the multi-partner Guam Coral Reef Response Team. The program currently utilizes a split-panel sampling approach, whereby a mix of permanent and non-permanent sampling stations (one sampling station = one transect) are visited within each HPRA. The HPRAs were selected by an advisory body comprised of reef managers, researchers, and technicians. The locations of the sampling stations within each HPRA are generated randomly using GIS software. Various coral reef surveys are carried out on an annual basis along the seaward slope between 7 and 15 m depth in the Tumon Bay Marine Preserve and in East Agana Bay, while surveys are carried out biennially within the Piti Bomb Holes Marine Preserve, the Achang Reef Flat Marine Preserve, the eastern side of the Cocos Barrier Reef (Cocos-East), and Fouha Bay. Surveys were also carried at along reef margin (1-2 m) and slope (2-15 m) of Western Shoals, in Apra Harbor, in 2011. The surveys, which are currently conducted by University of Guam Marine Laboratory biologists, and which were supported by NOAA PIRO through 2019, currently include benthic photo transects, stationary point count fish surveys, macroinvertebrate belt transects, and chain-length rugosity surveys. The GLTMP has conducted surveys at the Tumon and East Agana HPRAs since 2010 and the Piti HPRA since 2012. Data collection for the Achang and Cocos-East HPRAs began in 2014 and at the Fouha Bay HPRA in 2015. Baseline data is available for the Western Shoals HPRA from 2011 but this site has not been re-visited since its establishment due to shifting management priorities.

Fish are a culturally and economically valuable resource for the island of Guam (van Buekering et al., 2007). In recognition of the high value of this resource, reef fish surveys are a key component of the Guam Long-term Coral Reef Monitoring Program. Reef fish assessment surveys have been conducted at high priority reef areas around Guam since August 2010. The monitoring team uses a Stationary Point Count Method, adapted from Ault et al. (2006) and NOAA Fisheries, Coral Reef Ecosystem Division (Williams et al., 2011), to conduct the reef fish surveys. These monitoring data can be used to monitor the status and trends in fish density, biomass, diversity; to explore community structure by functional group and size structure; and examine changes in community structure over time.

IMPORTANT NOTE: Significant changes have been made to the fish SPC survey methodology since its first deployment in 2010. These changes, which are documented in the Data Quality and Lineage sections of this metadata record, must be considered in order to properly analyze these data. Also, please note that the results of a 2020 analysis of the fish SPC data conducted by Dr. Peter Houk of the University of Guam Marine Laboratory indicated that data collected in 2010 and 2011 by one observer did not meet quality assurance standards. In response to the results of this analysis observations recorded by this observer are not included in the dataset submitted to NCEI. However, these data can be made available upon request. More information regarding Dr. Houk's analysis can be found in the Data Quality section of the metadata record. Also note that a recent analysis conducted by the program coordinator showed that there were significant, consistent differences in biomass, density, and species richness values calculated using observations obtained by each of the two main fish observers. It is strongly suggested that any users of these data review the report in which these results are presented (https://www.uog.edu/_resources/files/ml/technical_reports/UOGML_TechRep170_GLTMP_2023.pdf) and reach out to the program coordinator to ensure the data are used appropriately. Please refer to the Supplemental Information section below for a list of important considerations and recommendations for any analysis of these data.