Linkages between reef fish demographics and benthic habitat characteristics in Tutuila, American Samoa and Main Hawaiian Islands

Benthic habitats play vital roles in the distribution and abundances of marine resources. Understanding how fish populations respond to variability of benthic habitat characteristics is essential for effective coral reef management and monitoring. A pilot study was conducted by NOAA Pacific Islands Fisheries Science Center (PIFSC) Coral Reef Ecosystem Program (CREP) to examine the relationships and linkages between the geomorphological benthic characteristics and fish demographics in Tutuila, American Samoa and the analysis was later expanded to the main Hawaiian Islands.

Geomorphological metrics characterizing benthic habitats including slope, rugosity, curvature, and convexity were derived using best available bathymetry for each area. The fish assemblages and abundance data were collected during Rapid Ecological Assessment (REA) surveys from 2010 to 2016. These fish data were collected according to a stratified random survey design using depth as an environmental correlate. Based on the analysis for Tutuila, American Samoa, preliminary evidence was found that using both depth and convexity to define strata may result in more precise estimates of fish biomass. This analysis was expanded to the main Hawaiian Islands for the subsequent year of the project, and found that including several other metrics in CREP's sampling design can enhance the estimates of fish biomass.

Results and data from the analysis for Tutuila, American Samoa can be accessed online via the Pacific Islands Benthic Habitat Mapping Center website at http://www.soest.hawaii.edu/pibhmc/pibhmc_documentation.htm#other_pubs.

The PIFSC administrative report from the analysis for the main Hawaiian Islands is in review as of Aug 2017 and will be available on the PIFSC website once published at https://www.pifsc.noaa.gov/library/staff_publications.php.