Analysis released juvenile Chum salmon prey source through DNA metabarcoding

Globally, many studies have focused on the prey sources of juvenile chum salmon. (Oncorhynchus keta). However, no previous studies have combined morphological analysis and DNA metabarcoding to investigate the prey sources of released juvenile chum salmon in freshwater habitat, where they first encounter their environment. This study investigated the prey sources of hatchery-reared juvenile chum salmon released into freshwater habitats in South Korea. By adopting a dual-methodological approach involving traditional morphological analysis and DNA metabarcoding, we examined the stomach contents of 45 juvenile chum salmon samples. We detected three families and four orders through morphological analysis, whereas DNA metabarcoding detected 29 species, 36 genera, and 16 families. The dominant taxa identified through morphological analysis were the family Chironomidae (adults: 16.94%), the order Trichoptera (adults: 10.89%), and the family Chironomidae (larvae: 6.05%). In contrast, DNA metabarcoding identified the genus Stylaria sp. (52.00%), the genus Cyclops sp. (10.29%), and the genus Tanypus sp. (7.00%) as dominant taxa. Comparing the number of individuals in the morphological analysis with the relative read abundance in DNA metabarcoding allowed us to explore the potential of DNA information to reflect the actual number of individuals. In addition, by examining preference calculations between a dual-methodological approach, we can investigate new preferred prey sources. These findings highlight the complex prey source of juvenile chum salmon, which depends on the analytical approach. Additionally, they indicate the potential for future DNA metabarcoding to reflect the results of morphological analysis.