Comparative study of ontogenetic trophic transition in large yellow croaker from Hong Kong and Taiwan using metabarcoding and isotope analysis

This study examines the feeding ecology and trophic dynamics of the critically endangered large yellow croaker (Larimichthys crocea) in the differing habitats of Hong Kong and Taiwan using 18S gut content metabarcoding and stable isotope analysis. As a top predator, the large yellow croaker plays a crucial role in regulating fish populations and maintaining balance in the marine ecosystem. We found isotopic niche differences between juveniles and adults, with juveniles consuming more planktonic prey and adults more benthic species. In the more disrupted waters of Hong Kong, disrupted ontogenetic trophic transitions were observed, as adults exhibited unexpectedly low stable nitrogen isotope values, indicating prolonged consumption of prey at low trophic levels. In contrast, the relatively less impacted waters of Taiwan showed normal ontogenetic trophic transition. These findings highlight the impact of habitat degradation on large yellow croaker and underscore the urgent need for conservation measures, including stricter fishing regulations and habitat protection, to preserve this essential species and its ecological role.