The salmon louse genome may be much larger than sequencing suggests

An update of the salmon louse (Lepeophtheirus salmonis) reference genome assembly

Salmon lice have plagued the salmon farming industry and have negatively impacted salmon populations in the wild. In response, researchers have generated high density genetic maps, genome assemblies, transcriptomes, and whole-genome resequencing data to better understand this parasite. In this study, we used long-read sequencing technology to update the previous genome assemblies of Atlantic Ocean salmon lice with a more contiguous assembly and a more comprehensive gene catalog of Pacific Ocean salmon lice. We were also able to further characterize genomic features previously identified from other studies by using published resequenced genomes of 25 Atlantic and 15 Pacific salmon lice. One example was further characterizing the ZW sex chromosomes. For both the Atlantic and Pacific Ocean salmon lice subspecies, we found that the female W-chromosome is only a small fraction of the Z-chromosome and that the vast majority of the W and Z-chromosome do not contain conserved regions (i.e. pseudoautosomal regions). However, conserved orthologous protein sequences can still be identified between the W- and Z-chromosomes.