Population structure and persistence of Pacific herring following the Great Tohoku earthquake

We evaluated the effect of the Great Tohoku earthquake, which occurred on March 11, 2011 in Japan, on the genetic diversity and population structure of Pacific herring (Clupea pallasii). Pacific herring (n = 4466) were collected between 2003 and 2014 through more than 20 sampling events during spawning periods at nine spawning sites throughout the Pacific herring distribution range in Japan. We measured them and genotyped 3784 fish at five microsatellite loci. Following the tsunami, the sea-spawning population at the center of the affected area was almost extirpated and was replaced by a genetically distinct lagoon-spawning population from an adjacent brackish lake. However, the pattern of gene flow was stable for populations, with unique admixture proportions in local populations despite the high gene flow (FST = 0.0184). Our results indicate that Pacific herring in Japan spawn in a range of salinities and exchange genes between local populations regardless of the spawning ecotypes. We...