Histopathology of adult pacific herring in Prince William Sound, Alaska, after the Exxon Valdez oil spill

Pacific herring (Clupea pallasi) sampled from oiled sites in Prince William Sound, Alaska, U.S.A., 3 weeks after the 1989 Exxon Valdez oil spill had multifocal hepatic necrosis and significantly increased tissue concentrations of polynuclear aromatic hydrocarbons (PAH). By comparison, Pacific herring from reference sites in 1989 and from all sites in 1990 and 1991 did not have hepatic necrosis or increased PAH concentrations. Adult Pacific herring were sampled for histopathology of liver, spleen, and kidney from oiled and reference sites in April (1989 and 1991) and October (1990 and 1991). Increased scores for macrophage aggregates contributed to significant differences in 1990, but these differences probably resulted from sampling older fish from the oiled site. Naphthalenes were the predominant PAH in all tissue samples. The development of hepatic necrosis and the predominance of naphthalenes in samples from 1989 is consistent with recent laboratory study in which crude oil exposure resulted in dose-dependent expression of viral hemorrhagic septicemia virus (VHSV). We conclude that Pacific herring were exposed to Exxon Valdez oil in 1989 and that development of hepatic necrosis in exposed fish probably was a result of VHSV expression.