††slugcomment: Draft version Seriola lalandi comprises three genetically distinct clades, with S. lalandi lalandi inhabiting the Southern Hemisphere. While a chromosome-level genome exists for the Northwestern Pacific S. lalandi aureovittata, no such resource is available for S. lalandi lalandi, limiting genetic research and aquaculture advancements. This study presents a high-quality chromosome-level genome assembly of S. lalandi lalandi using Illumina short-read, long-read (ONT) and Hi-C. A total of 289.12 Gb of raw genomic data was generated, and a final assembly of 644 Mb was produced with 99.64% of the assembled bases anchored into 24 pseudo-chromosomes. Genome annotation identified 24,600 protein-coding genes, with 96.1% completeness based on 3,640 BUSCO orthologs. Additionally, the complete mitogenome was assembled and annotated for S. lalandi lalandi. This genomic resource will help to inform comparative genomic studies, improve aquaculture breeding programs, and support appropriate fishery strategies, particularly in Aotearoa New Zealand, where S. lalandi lalandi is a culturally significant taonga species for M¯aori.

Seriola lalandi comprises three genetically distinct clades, with S. lalandi lalandi inhabiting the Southern Hemisphere. While a chromosome-level genome exists for the Northwestern Pacific S. lalandi aureovittata, no such resource is available for S. lalandi lalandi, limiting genetic research and aquaculture advancements. This study presents a high-quality chromosome-level genome assembly of S. lalandi lalandi using Illumina short-read, long-read (ONT) and Hi-C. A total of 289.12 Gb of raw genomic data was generated, and a final assembly of 644 Mb was produced with 99.64% of the assembled bases anchored into 24 pseudo-chromosomes. Genome annotation identified 24,600 protein-coding genes, with 96.1% completeness based on 3,640 BUSCO orthologs. Additionally, the complete mitogenome was assembled and annotated for S. lalandi lalandi. This genomic resource will help to inform comparative genomic studies, improve aquaculture breeding programs, and support appropriate fishery strategies, particularly in Aotearoa New Zealand, where S. lalandi lalandi is a culturally significant taonga species for M¯aori.

Climate-driven range expansion is reshaping species distributions worldwide, altering population connectivity and complicating stock assessment in many marine taxa. In Aotearoa New Zealand, Yellowtail Kingfish (Seriola lalandi lalandi) have extended southward from their historically northern distribution, prompting renewed questions about stock boundaries and connectivity across the range. Here, we present the first comprehensive evaluation of sagittal otolith shape variation in this species and assess whether otolith morphology can serve as an indicator of ongoing range-expansion dynamics. We analysed otoliths from 112 individuals collected across five regions using wavelet-based contour descriptors and traditional shape indices to test for spatial structure and signatures of expansion. Wavelet-based contour descriptors differed significantly between Auckland West— the traditional home range of Yellowtail Kingfish— and all other sampled regions, which represent the species’ ongoing range expansion. Classification analyses further achieved the highest assignment success for Auckland West fish, underscoring the utility of otolith shape for identifying individuals from this historic northern range. Together, these findings demonstrate the value of otolith morphology as a tool for delineating stock structure and supporting adaptive fisheries management under accelerating climate-driven distributional shifts.