Frequent Questions—Marine Mammal Euthanasia

Despite the best efforts of the Marine Mammal Stranding Network, saving live-stranded marine mammals that are sick or injured is not always possible. Sometimes the most humane course of action may be euthanasia to end the animal’s suffering. The decision to euthanize a compromised marine mammal is never taken lightly. Trained and authorized responders make the decision in consultation with marine mammal biologists, veterinarians, and NOAA Fisheries staff. The euthanasia procedure follows specialized protocols, and is conducted humanely, respectfully, and in accordance with nationally approved veterinary methods.

What is euthanasia?

In veterinary medicine, euthanasia typically describes the humane ending of life in a way that minimizes or eliminates pain and distress. It reflects the veterinarian or authorized responder’s professional judgment on what is the best, most compassionate outcome for an animal. Just as people agonize over the decision to euthanize a beloved pet, it is a difficult decision for professional responders in the Stranding Network, when faced with the situation of euthanizing a marine mammal that is suffering. 

When does the Stranding Network consider euthanasia for marine mammals? 

Marine mammals strand for a variety of reasons, and Stranding Network responders carefully and individually evaluate live stranding events. For example, a stranded marine mammal may: 

• Be in overall poor health (e.g., emaciated, malnourished)
• Have severe internal or external injuries 
• Have disease with limited or no treatment options
• Be a dependent animal (calf or pup) stranded alone
• Be an offshore species that has historically not fared well in rehabilitation

In these cases, the animal’s chances of recovery and return to the wild are near zero. Attempts at treatment would likely extend the animal’s suffering prior to death, which makes euthanasia the most humane course of action. Live stranded marine mammals, particularly large whales, can live for hours—even days—with undue pain, stress, and suffering, if not euthanized.

Several factors are considered before an animal is euthanized: 

• Size of the animal
• Environmental conditions including access to the animal
• Condition of the animal including its health or injuries
• Available resources including space at local rehabilitation facilities 
• Length of time out of water for whales 
• Safety of the response team 

Who decides whether to euthanize a marine mammal? 

The decision to euthanize an animal is never taken lightly and is an action of last resort after all options are exhausted. Stranding Network responders monitor live-stranded marine mammals and perform a comprehensive health assessment to determine the appropriate course of action. For smaller animals, this course of action can be accomplished within hours. Live-stranded large whales are typically given one to two tidal cycles, or about 12–24 hours, to try and refloat (either naturally or with intervention). If the whale remains on shore after one to two tidal cycles without refloating, euthanasia may be considered. After the health assessment, Stranding Network responders decide whether or not to euthanize in consultation with professional marine mammal biologists, veterinarians, and NOAA Fisheries staff.

How are marine mammals euthanized? 

Experienced and qualified personnel conduct the euthanasia procedure humanely, respectfully, and efficiently in concurrence with the American Veterinary Medical Association guidelines. Over the past several decades, the Marine Mammal Health and Stranding Response Program has worked with the Stranding Network to develop protocols and procedures for responding to live marine mammals that are stranded or in distress. This ensures the health, welfare, and safety of human responders and animals. 

The goal of euthanasia is to reduce an animal’s pain and suffering so that it may die as quickly and peacefully as possible. Approved euthanasia methods for marine mammals result in rapid loss of consciousness prior to loss of muscle movement, cardiac or respiratory arrest, and brain function. 

Prior to euthanasia, marine mammals are generally given a sedative to reduce pain and stress. This often results in the animal becoming unconscious, which may even suffice for euthanasia if an animal is already debilitated. Sedation also decreases the risk of serious injury to responders. This process of sedation, followed by an injection of authorized lethal agents, is similar to the method that veterinarians use when euthanizing pets.

Approved euthanasia methods are commonly chemical and/or physical. All available and approved euthanasia methods have pros and cons, or limitations, depending on the species and habitat. Euthanasia must be conducted by trained individuals and may require a specialized license to possess certain drugs or operate firearms. Some methods may only be performed after the animal is sedated or as a method of last resort.

Chemical Methods

Chemical (pharmaceutical) methods include injectable or inhalant drugs (e.g., tranquilizers, sedatives, painkillers). In the United States, injection of an authorized drug is the preferred and most common euthanasia method for live-stranded marine mammals because it is quick and effective. Unlike some euthanasia chemicals, potassium chloride poses little risk of secondary poisoning to other animals— such as birds, coyotes, or sharks—that may scavenge the carcass after disposal. Veterinarians and responders favor potassium chloride, following deep sedation, for large whales that cannot easily be removed from the environment.

Physical Methods

Physical methods include gunshot (which should only be used with smaller marine mammals), or exsanguination (blood draining) following deep sedation. Physical methods are rarely used. They are generally reserved for remote or logistically challenging situations where the carcass cannot be removed from the environment, or there is no access to euthanasia drugs or veterinary support.

Trained and authorized personnel may use firearms to ease pain and suffering. If conducted properly, firearms are an effective method of euthanizing small marine mammals (up to 8 meters in length), and result in a rapid death. Firearms are not recommended for larger marine mammals, or certain species, such as sperm whales, as the size and density of their skull may restrict bullet penetration. In these cases, if injection of an authorized drug is also not an option, blood draining is an appropriate method, but only if heavy pre-euthanasia sedation is used. 

When would a marine mammal not be euthanized?

Human safety is paramount. Euthanasia may not always be feasible or safe. Large whales can be bigger than a school bus, and animals in distress can be unpredictable. Live animals may be in the surf zone, in a rocky area, or at the bottom of a cliff, where euthanasia cannot be safely conducted. Free-swimming injured animals may not be able to be captured or remotely treated. In such cases, the animal may be left to die without intervention.

Who can conduct marine mammal euthanasia?

National Marine Mammal Stranding Network responders are authorized to conduct marine mammal euthanasia. NOAA Fisheries has an oversight role for marine mammal strandings, and some Stranding Network actions (especially with threatened or endangered species) are authorized under a permit issued to the Marine Mammal Health and Stranding Response Program pursuant to the Marine Mammal Protection Act and Endangered Species Act.

Performing euthanasia is a technically challenging and potentially dangerous undertaking, especially with large whales. Only an authorized Stranding Network member or veterinarian with experience with the species and trained in euthanasia methods for that species should perform euthanasia. 

How long does euthanasia take?

Time to death varies and depends on the species, size and health of the individual, and the method of euthanasia.

Large Whales 

In sedated large whales, time to death ranges from about 50 minutes to 2.5 hours given their immense size and their relatively slow metabolism. From the time potassium chloride is administered, time to death ranges from 4 to 10 minutes. 

Small Cetaceans and Pinnipeds

Time to death following chemical euthanasia methods varies, but is typically between a few seconds and several minutes. Firearms, if used correctly by trained and experienced personnel, result in a rapid death.

Following the administration of euthanasia, the animal’s death must be confirmed. Typically, the absence of a heartbeat is the only reliable confirmation of death; however, a heartbeat can be challenging to detect in large marine mammals in some field settings. Other signs that may help confirm death include sustained loss of eye and blowhole reflexes, lack of response to stimulus, and absence of respirations. 

Do euthanized carcasses harm the environment?

Rarely, a live-stranded marine mammal is euthanized with chemicals that may harm scavengers such as  birds, coyotes, sharks. In these cases, the carcass needs to be disposed of in a safe manner that prevents risk to wildlife and the environment. Disposal options include incineration, rendering, composting, or burial in a licensed landfill. If an animal has been euthanized using potassium chloride (which has little risk of secondary poisoning) or by physical methods, there is less risk to the environment. 

Additional disposal options may include leaving the carcass in place, beach burial, or towing the carcass out to sea. If sedatives were used prior to euthanasia, the injection sites where those chemicals are concentrated are cut out and disposed of appropriately. All carcass disposal options follow local, state, tribal, and federal laws and regulations.

Is euthanasia painful for marine mammals?

The goal of euthanasia is to make the death of an animal as painless, quick, and free of distress as possible. Euthanasia methods are intended to result in rapid loss of consciousness prior to loss of muscle movement, cardiac or respiratory arrest, or brain function. Prior to euthanasia, marine mammals are generally given a sedative to reduce pain and stress, which often results in the animal becoming unconscious. Species-specific sedation and euthanasia protocols are available for some species and should be used whenever possible to provide the best euthanasia process for each animal.

How do marine mammals react when chemically euthanized?

Although some reactions to chemical euthanasia are more commonplace or predictable, responses to euthanasia by marine mammals vary between taxa, species, and individuals of the same species. They also depend on the chosen method of euthanasia. In some cases, cetaceans may respond to chemical methods by opening their mouth or raising their pectoral flippers or flukes, even though they are sedated and typically not conscious. This is sometimes referred to as the “last swim.” This may be difficult to witness; however, the procedure is ultimately helping to minimize the animal’s suffering.