How do oil spills impact wildlife?

Many things can influence how much harm an oil spill causes. The impacts depend on where the oil is spilled, what kinds of wildlife are found there, and the amount and type of the oil, among other things. Generally, oil spills harm ocean life in two ways:

Fouling or oiling: Fouling or oiling occurs when oil physically harms a plant or animal. Oil can coat a bird’s wings and leave it unable to fly, or it can strip away the insulating properties of a sea otter’s fur, putting it at risk of hypothermia. The degree of oiling often impacts the animal’s chances of survival.

Oil toxicity: Oil contains many toxic compounds that can cause severe health problems and even death. Many birds and animals can ingest (swallow) oil when they try to clean themselves, which can poison them. Marine mammals, sea turtles, and birds can also breathe in oil fumes at the surface.

Depending on where and when a spill happens, up to hundreds or thousands of birds and mammals can be killed or injured. Spilled oil can impact habitats from the deep sea to marshes and other nearshore areas. Since most oils float, it most often affects creatures like sea otters and seabirds that are found on the sea surface or on shorelines. When it reaches shallow waters, oil can also significantly impact fish and shellfish, including commercially important species like salmon or mussels. In some cases, oil can sink and impact deep-sea communities such as corals.

While some fish can swim out of areas impacted by oil spills, large spills or spills in shallow water can still harm them. Fish eggs and shellfish are very sensitive to oil pollution. The Exxon Valdez tanker spill in 1989 killed billions of salmon and herring eggs. While salmon populations have since recovered, by 2014, herring had still shown no signs of improvement after the spill.

In addition to those billions of fish eggs, the Exxon Valdez oil spill killed around 250,000 seabirds, 22,800 sea otters, hundreds of seals and bald eagles, and potentially dozens of killer whales. Some of those species (like killer whales) have yet to show progress toward recovery. Oil directly impacted 200 miles of shoreline, but scientists have found small concentrations of oil on more than 1,300 miles of shoreline in the region.

The Deepwater Horizon spill affected so many types of wildlife and habitats over such a large area that the impact is considered an injury to the entire ecosystem of the northern Gulf of Mexico. This spill directly impacted more than 1,300 miles of shoreline, and the surface oil slick during the spill extended over 43,300 square miles. Scientists estimated that the oil spill resulted in the death of:

• Up to 5 trillion newly hatched fish
• Up to 84,500 birds of at least 93 species
• Between 4,900 and 7,600 large juvenile and adult sea turtles
• Between 55,000 and 160,000 small juvenile and hatchling sea turtles

Wildlife recovery, cleaning, and rehabilitation is often an important part of oil spill response. However, wildlife is difficult to find and catch, oil spills can happen over wide areas, and some animals (like whales) are too big to recover. Unfortunately, it’s unrealistic to rescue all wildlife impacted during oil spills.