eDNA assessment of pelagic fish diversity, distribution, and abundance in the central Pacific Ocean

In open ocean environment with rich biodiversity, the assessment of fish resources is critical to the development of marine ecosystems and the sustainable use of resources. Environmental DNA (eDNA) metabarcoding is a new, constantly evolving tool and has recently been used to examine deep-sea eukaryotic diversity and communities. Here, eDNA metabarcoding was used to monitor fish populations in the central Pacific Ocean to understand the distribution of marine biodiversity in the region and investigate the abundance of dominant species. Water samples in present study were collected from three habitats, a total of 73 fish species from 41 families were detected, of which, 15 fish species from 10 families were found to be dominant species. What is more, the dominant species: Elagatis bipinnulata, Encrasicholina punctifer, Euthynnus affinis, lisha elongata, Nomeus gronovii, Reinhardtius hippoglossoides, Vinciguerria nimbaria had significant differences between habitats (p<0.05 or p<0.01). Alpha diversity indicated that the fish community composition in the three habitats was generally high, which was the highest at the Equator habitat. Beta diversity based on Bray–Curtis and Jaccard indices indicated that the fish composition of the three habitats overlapped in part, but there were not significantly different (p >0.05). Regression analyses indicated that there was an overall correlation in the biomass and reads richness (p <0.05) of Thunnus obesus and Katsuwonus pelami This study not only verities the validity and accuracy of eDNA technology applied to pelagic fish biodiversity assessment but also provides systematic cases for fish resource surveys in other sea areas and lays the foundation for oceanic fish resource monitoring.