It's difficult to generalize about the toxicity of oil spills to killer whales (Orcinus orca); however, we do know that oil exposure can cause external problems (such as skin or eye irritation or ulceration) and internal problems when oil is ingested or inhaled. Some research suggests that oil exposure can result in population-level impacts (Matkin et al. 2008).

Evidence suggests that killer whales are unlikely to detect and avoid spilled oil. In the coastal waters of the Pacific Northwest, the southern resident killer whale population is listed as endangered under the U.S. Endangered Species Act and is also protected under the Marine Mammal Protection Act.

When oil spills occur, "hazing" methods are sometimes used to deter whales from the area of the spill. Among the hazing methods considered are the following:

• Acoustic deterrent devices, which make sound not loud enough to cause pain but which is audible to marine mammals.
• Pre-recorded killer whale calls.
• Oikomi pipes, which are pipes made of reverberant metal that can deter or herd the whales.
• Boat traffic that provides noise and motion.
• Helicopters that generate considerable noise and wave movement at close range.
• Fire hoses that can direct streams of water at whales.

Specific hazing methods, if any, recommended at the time of a spill will be those that have the greatest chance of success, depending on current conditions and information. Whether or not killer whales can be deterred from entering an oil spill is directly related to the degree to which the whales are attracted to an area.

No one individual hazing technique will work in all situations. Unfortunately, hazing and monitoring activities are the only mitigation measures possible during an oil spill, as capture and rehabilitation of killer whales is improbable.

The Northwest Wildlife Response Plan within the Northwest Area Contingency Plan (NWACP) includes response guidelines to protect killer whales (see NWACP Chapter 9310). Supporting information to the 2020 NWACP, including contact information and more information on alternative marine mammal hazing techniques, can be found in the document Southern Resident Killer Whale Oil Spill Resources [PDF, 172 KB]. In addition, NOAA Fisheries has drafted an Implementation Plan [PDF, 346 KB] for hazing of Southern Resident killer whales, which provides guidance for whale monitoring and hazing activities as part of the NWACP.

How Do You Keep Killer Whales Away From an Oil Spill? NOAA has identified tools and techniques to deter endangered killer whales from swimming through oil spills.

Learn more about protecting Puget Sound killer whales, from NOAA Fisheries: West Coast Region:

• Killer Whale (Orcinus orca)
• Endangered Species Act Status of Puget Sound Killer Whales
• Recovery Plan for Southern Resident Killer Whales (Orcinus orca) [PDF, 1.7 MB]

How to keep killer whales out of oil spills: A SeaDoc Society article about its partnership with NOAA to help protect the Salish Sea's resident and transient killer whales from spilled oil.