Background/Aims:Marine fisheries provide valuable seafood resources critical for human nutrition. However, the high dispersal ability and broad geographic ranges of marine fish complicate stock assessment. The reliability of traditional fishery-dependent models is often questioned when fishery data are insufficient, prompting greater use of stock identification methods to inform targeted management. Due to limited discriminatory power of single technique, applying multi-disciplinary approaches are increasingly employed for a more comprehensive interpretation of species stock structure. This study employed an integrative approach, using otolith and genomic markers, to clarify the population structure and connectivity of the commercially targeted silver trevally (Pseudocaranx georgiaus) in Australia.
Methods:We applied genome-wide Single Nucleotide Polymorphisms (SNPs) to detect patterns of genetic variations among the regions. Additionally, otolith shapes and chemistry were applied to infer phenotype traits individuals' lifetime. The combined approach can offer insight on the evolutionary lineages of the species to uncover stock structure in generational scale, while reflecting individual patterns in lifetime.
Results: The overall findings revealed two distinct biological stocks in Australia, one distributed along the east coast and the other along the west coast. Genomic analyses indicated high connectivity within each stock suggesting, substantial gene flow, but low connectivity between stocks, reflecting long term separation. The otolith analysis further provides a finer scale on stock boundary delineation within the Bass Strait, between Port Fairy and Corner Inlet. A potential factor accounting for the findings relates to the presence of the historical Bassian Isthmus during the Last Glacial Maxima (LGM), which may have restricted movement and gene flow, leading to population isolation. We also hypothesize the prevailing ocean current systems in the region have contributed to maintain this separation in the post-LGM period.
Conclusion: This study reflects that the current management practices of silver trevally does not align with the biological stock structure revealed in our findings. This highlights the need for cross-jurisdictional collaboration in monitoring, assessing and managing of this commercially important species. This integrative approach demonstrates the value of multidisciplinary tools in resolving stock structures and informing effective fisheries management.