New federal research shows that embryonic salmon and herring exposed to very low levels of crude oil can develop heart defects that hurt their chances for survival.
The National Oceanic and Atmospheric Administration scientists say their conclusion could explain why herring and pink salmon populations in Prince William Sound declined after the 1989 Exxon Valdez spill.
Research toxicologist John Incardona of NOAA Fisheries in Seattle says in a statement that delayed effects of the spill may have been important contributors to the declines.
Scientists exposed embryonic salmon and herring to low levels of crude oil. They grew and swam slower than fish that were not exposed, making them more vulnerable to predators.
Exposure to oil as embryos also altered the structural development of the hearts of juvenile fish.