Balaenoptera robusta Lilljeborg, 1861 p.602; Type locality- Graso Island, Uppland, Sweden.
Agaphelus glaucus Cope, 1868 p.225; Type locality- Monterey Bay, California.
Rhachianectes glaucus: Andrews, 1914 p.232; Kishida, 1924 p.320; Kuroda, 1938 p.12.
Eschrichtius gibbosus: Ellerman & Morrison-Scott, 1951 p.713; Won, 1958 p.434; Won, 1967 p.81; Won, 1968 p.233. E. robustus: Kim et al., 2000 p.66; Kim, 2004 p.225.
Range: The Korean stock almost became extirpated with the harvest of five gray whales in 1964 (Park 1987). The possible extinction of the Korean stock in the 1970s was debated (Bowen 1975; Brownell & Chun 1977). However, the re-discovery of gray whales in the 1990s ensured the survival of the Korean stock, with no more than 200 individuals surviving in the West Pacific Ocean (Reeves & Kenney 2003). Historically E. robustus migrated through Ulsan twice a year, from late November to the end of January and from mid-March to mid-May (Fig. 81). This whale is commonly observed in the East Sea, but no recent observations have been reported in the waters of Korea.
Remarks: Pre-whaling genetic bottleneck in gray whales has been suggested (Alter et al. 2007). Gray whales feed in Arctic and subarctic benthic environments, and marine biologists assume gray whales have a sensitivity to changes in climate, and climatic events such as the Medieval Warm Period (ca. 900–1200 AD) or Little Ice Age (ca. 1300–1850 AD) could have caused population declines. The poorly understood relationship between populations of the gray whale and climate-driven ecosystem features such as sea ice, freshwater input to near-shore benthic ecosystems, and prey preference could have caused the distinction of this species from other taxa (Perryman et al. 2002, Moore et al. 2003). A recent genetic study supported the hypothesis that gray whales experienced a recent, major population decline (Alter et al. 2007). The small F ST value (0.1125) between eastern and western individuals supports the monotypic status of the species (Alter et al. 2012). Because of differences in haplotype frequencies between eastern and western lineages (among 36 haplotypes, three were unique to the western population, 26 to the eastern, and seven were shared), the Korean stock could be a distinct subspecies due to its isolation and lack of gene flow (LeDuc et al. 2012).
Conservation status: Ever since R. C. Andrews (1914) reported a ‘Korean stock’ of gray whales, Koreans have favored the gray whale like national whale because of the word ‘Korean’ stock. The South Korean government designated this species with a migration route in the East Sea a Natural Monument in 1962 and a Protected Marine Species in 2007. CITES listed the gray whale on Appendix I. The North Korean government classified this species as ‘Rare’ (MAB National Committee of DPR Korea 2002).