Studies On Population Resources And Molecular Genetic Characteristics Of Spotted Seals (Phoca Largha) In Chinese Waters

Spotted seal (Phoca largha), is a coldwater marine mammal widely distributed in the North-Western Pacific Ocean, one of second-class protected endangered animals in China, the only pinniped animal which naturally breed in Chinese waters. Liaodong Bay of Bohai Sea is the southernmost one of the eight breeding concentrations of spotted seals around the world. For better understanding and protecting spotted seals, the habitats, population dynamics, heavy metal accumulation and molecular genetic characteristics of spotted seals are investigated. The results are as follows:The haul out sites in the habitats of seals in Bohai Sea include muddy beaches in Shuangtaizi River estuary region of Liaoning Province, shallow reefs around islands of Miaodao Islands of Shandong Province and tideland rocky beaches near Huping Island of Dalian City. The periods of seals appearing in habitats are from March to May each year. In this study period from 2002 to 2008, the individual numbers of seals in these habitats fluctuate slightly.The concentrations of heavy metal elements are determined in muscle, kidney and liver in spotted seals from Bohai Sea. The results suggest that accumulation of toxic elements such as Hg, Cd, Pb and As in tissues of spotted seals are relatively low and do not reach the lethal criteria.Partial mtDNA sequence analysis shows that the genetic distance, haplotype and nucleotide diversities in control region of spotted seals from Liaodong Bay are relatively lower than those of spotted seals from Sea of Japan, indicating that the genetic diversity of spotted seals in Liaodong Bay is low.The results of genetic diversity analysis by using microsatellite markers show that the average number of effective alleles (2 ~ 4) and expected heterozygosity (0.24 ~ 0.72) of spotted seals from Liaodong Bay population are at a low level, indicating that the population of Liaodong Bay spotted seal have suffered a decrease in genetic variability and the population probably suffer a degree of bottleneck effect in the past.Forty alleles are obtained in 41 MHC-I gene sequences from nine spotted seals, indicating that spotted seals from Liaodong Bay with high polymorphism in MHC-I gene.The present syudies would provide useful data for the conservation and management of Liaodong Bay spotted seal colony.