Management Without Borders: Population Connectivity of the “California” Spiny Lobster (Panulirus interruptus)

International cooperation is essential to effectively manage fisheries species whose ranges do not adhere to geopolitical borders. The California spiny lobster, Panulirus interruptus is fished commercially and recreationally throughout its range from Baja Magdalena, Mexico to Point Conception, California. Previous studies provide indirect evidence that California lobster populations may receive a substantial number of recruits from populations in northern and central Baja. We used a 494-base-pair fragment of the cytochrome oxidase I region of the mitochondrial DNA genome, and 7 nuclear microsatellite markers to investigate whether lobster populations in California are locally self-seeding or rely on cross-border recruitment to persist.  We genotyped 989 samples from 17 populations throughout the range of P. interruptus, and found significant structure exists among populations, but with low spatial signal (f_st = 0.006, p = 0.001; Fst = 0.004, p < 0.0001).  These results are surprising given the approximate year-long larval duration in this species.  Our results imply a large, diverse, and meta-population with certain sub-populations relying to a greater extent on self-seeding for persistence. Migrate analyses suggest that there are large influxes of larvae from Mexico into California, but that gene flow across the international border likely occurs in both directions, and many populations rely on self-seeding to persist. We recommend cross-border cooperative management to maintain sustainable fisheries for this species, and offer management recommendations for the Marine Life Protection Act Initiative in Southern California.