In 1988, the first marine strain of VHSV, now designated type IV, was found in normal-appearing salmon returning from the Pacific to rivers of Washington State. This strain and other marine strains were not lethal to rainbow trout. The discovery prompted further studies, and by the mid-1990s, marine VHSV was found in eight species along the northern North America's Pacific coast, and 14 species in and around the Atlantic's North Sea. 1996 saw the first VHSV in Japan, among Japanese flounder farmed in the Seto Inland Sea, and different genotypes have appeared in different areas since then. Type IV was later found off North America's northern Atlantic coast, in Atlantic herring ("Clupea harengus") mummichog ("Fundulus heteroclitus"), stickleback ("Gasterosteus aculeatus aculeatus"), brown trout ("Salmo trutta"), and striped bass ("Morone saxatilis"), as well as dozens of freshwater species in the Great Lakes.