Chromosome-level genome of the Adriatic sturgeon, Acipenser naccarii: A resource for polyploid fish genomics.

The Adriatic sturgeon, Acipenser naccarii, a tetraploid species endemic to the North Adriatic region, has experienced significant population declines, resulting in its classification as "Critically Endangered" by the International Union for Conservation of Nature (IUCN). Historically widespread in the Adriatic Sea's tributaries, the species is now at high risk of extinction with occasional reproductions occurring in the wild. Using long-read sequencing (PacBio HiFi) and chromatin conformation capture sequencing (Hi-C), we generated a phased reference genome for the tetraploid Adriatic sturgeon. The haploid assembly spans 1.94 Gb across 2,083 scaffolds, with a contig N50 of 1.024 Mb, a scaffold N50 of 39.6 Mb, and a scaffold L90 of 276. Approximately 80% of the genome is contained within the first 60 scaffolds, indicating a high degree of contiguity. The Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness score of the haploid assembly reached 88.9%, whereas combined metrics for all four haploid assemblies increased to 94.1%. This comprehensive genomic resource provides valuable insights into the genetic and evolutionary mechanisms of polyploidy and, more specifically, it will improve our understanding of the genetic diversity of the Adriatic sturgeon, thereby informing targeted conservation strategies for this critically endangered species.