A Chromosome-Level Genome Assembly for the Beach-Spawning California Grunion, Leuresthes Tenuis

We generated the first chromosome-level genome assembly for California grunion, Leuresthes tenuis, using PacBio HiFi long reads and Omni-C chromatin-proximity sequencing, yielding a 0.917 Gb genome with a scaffold N50 of 35 Mb and a BUSCO completeness score of 99.37. This beach-spawning marine silverside is the target of a unique recreational hand-grab fishery during its nocturnal spawning runs. Regulation of this fishery, initiated in 1927, remained unchanged from 1949 to 2022, when recent data suggesting a stock decrease led California Department of Fish and Wildlife to reduce the fishing season length. California grunion are endemic to the coast of California and northern Baja California, but within the last two decades the northern limit of spawning has expanded roughly 470 kilometers from Point Conception to north of San Francisco Bay. This genome will facilitate studies addressing the temporal and spatial genetic stock structure, and recent range expansion, of this unique charismatic native species and will also allow assessment of genetic responses to present and future environmental challenges such as changing temperature, and pollution as well as the impacts of harvest and effects of management.