International Journal of Marine Science, 2025, Vol.15, No.3, 130-143 http://www.aquapublisher.com/index.php/ijms 139 importance of genetic resource protection. As molecular data reveal the complex pedigree structure and high level of cryptic genetic diversity within the Spanish mackerel genus, we are more aware that each pedigree and each population may contain unique adaptive genetic resources. Once these genetic units disappear due to overfishing or improper release, it will be an irreversible loss (Jeena et al., 2022; Yang et al., 2023). Therefore, in the development of aquaculture, the protection of wild genetic resources must be considered simultaneously. Specifically, a germplasm resource bank can be established, such as live seed preservation or frozen sperm/embryo preservation of Spanish mackerel from different geographical groups, in preparation for future breeding and population recovery. At the same time, organizations such as IUCN are also calling for the inclusion of genetic diversity indicators in species red list assessments to encourage countries to take genetic conservation actions (Lorenzen et al., 2021). On the other hand, phylogenetic research also provides direction for genetic improvement (breeding). Genomic data can help us discover useful genetic variations and accelerate the cultivation of high-yield and high-quality aquaculture varieties. For example, by comparing the genomes of different lineages, candidate genes related to traits such as growth, disease resistance, and environmental tolerance can be located. If a lineage is found to have unique dominant alleles on these genes, it is possible to consider introducing the pedigree of the lineage during breeding to enhance these traits. For example, assuming that a lineage of Spanish mackerel in the Indo-Pacific region has a high tolerance to warm water hypoxia, its genes can be integrated into the breeding program to meet the aquaculture challenges brought about by rising water temperatures. Breeding in the genomic era has shifted from traditional phenotypic selection to whole genome selection (GS), using tens of thousands of molecular markers to predict individual breeding values. Although there is no dedicated GS research on emerging aquaculture varieties such as Spanish mackerel, it is entirely possible to learn from the successful experience of other species (Yáñez et al., 2023). For example, in farmed fish such as salmon and tilapia, GS has significantly improved the selection efficiency of disease resistance and growth traits. 6.2 Disease resistance and environmental adaptability breeding strategies The two eternal themes in aquaculture are disease prevention and control and environmental adaptation. Phylogenetic and genomic studies provide us with scientific basis for improving mackerel breeding strategies in these two aspects. First, in terms of disease resistance breeding, genome-wide association analysis (GWAS) can help identify genetic markers associated with disease resistance. Although mackerel farming has not yet been carried out on a large scale, it is foreseeable that under intensive farming conditions, common diseases such as bacterial sepsis and parasitic infections may pose a threat to mackerel (Oliveira et al., 2021; Pan et al., 2024), The use of genomic selection to improve disease resistance traits has been successful in other species: for example, the application of GS in Pacific oysters has improved resistance to Vibrio disease; selective breeding in Atlantic salmon has significantly reduced the incidence of ISA virus. In terms of environmental adaptability, global climate change and environmental fluctuations require farmed varieties to have a wider tolerance range. Phylogenetic information can guide us to find potential environmental tolerance gene pools. For example, Japanese mackerel is distributed in the northern edge and survives and reproduces at lower water temperatures, so it may have genes related to cold resistance; while narrow-banded mackerel reproduces in high-temperature, high-salinity tropical waters and may have stronger resistance to high temperatures. If the lineages with different environmental adaptation characteristics can be hybridized to cultivate new strains with both wide temperature and wide salt tolerance, it will be beneficial to expand the breeding area and improve the robustness of breeding (Gao et al., 2024). In breeding for disease resistance and environmental adaptability, in addition to traditional breeding, gene editing can also be used to accelerate the realization of target traits. CRISPR-Cas9 technology has demonstrated its power in the field of aquaculture. For example, editing specific genes in carp can enhance disease resistance, and editing growth-related genes in zebrafish can double the growth rate. For mackerel, if key disease resistance or environmental tolerance gene sites have been identified, such as mutation sites of genes encoding immune
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