Frequent Questions: West Coast Gray Whale Unusual Mortality Event

Why is NOAA involved in declaring a Unusual Mortality Event?

Conserving and restoring protected resources including marine mammals, fish, and corals is a core mission for NOAA Fisheries. NOAA Fisheries is responsible for the protection and conservation of all whales, dolphins, porpoises, seals, and sea lions under the Marine Mammal Protection Act (MMPA). We depend on healthy marine species for maintaining balanced and thriving ocean ecosystems and coastal communities. NOAA Fisheries relies on the best available science to carry out the mandates of the Marine Mammal Protection Act, including reducing the negative effects of human activities on protected species and their habitats. We develop and implement plans to guide species recovery and conservation, enforce regulations against harming protected species, and conduct high-quality science focused on conservation.

What is an Unusual Mortality Event?

An Unusual Mortality Event, or UME for short, is defined under the Marine Mammal Protection Act as a stranding event that is unexpected, involves a significant die-off of any marine mammal population, and demands immediate response. Seven criteria determine whether a mortality event is “unusual.” If the Working Group on Marine Mammal Unusual Mortality Events (Working Group), a group of marine mammal health experts, determines that an event meets one or more of the criteria, it forwards a recommendation to NOAA’s Assistant Administrator for Fisheries to declare an UME.

What criteria have been met?

In this case, the Working Group concluded that two of the seven criteria used to determine an UME have been met. These include the following criteria:

1. A marked increase in the magnitude or a marked change in the nature of morbidity, mortality or strandings when compared with prior records.

5. Affected animals exhibit similar or unusual pathologic findings, behavior patterns, clinical signs, or general physical condition (e.g., blubber thickness).

How widespread is this UME?

Increased mortalities of gray whales have been observed along the entire west coast of North America from Mexico to Alaska.

When did the first reports of increased strandings of gray whales occur?

The first reported stranding in the United States for this event was on January 15, 2019 and the first reported stranding in Mexico occurred on December 17, 2018.

How many gray whales are involved in the event?

You can track gray whale stranding numbers on our Gray Whale UME webpage. That page also has an interactive map so you can visually see gray whale stranding locations over time during the UME.

Why are gray whales stranding?

The ongoing investigation has identified several likely contributors, including ecological changes in the Arctic leading to malnutrition in some whales. These changes are affecting the sea-floor and the small amphipods and other invertebrates living in and above the sediment and in the water column that gray whales feed on each summer, according to newly published research (Moore et al. 2022). Additionally vessel strikes and evidence of entanglement and killer whale predation have also been found to have contributed to the deaths of some of the whales, although the majority of stranded whales do not have evidence of human interactions.

What happens to the carcasses of stranded whales?

In most cases, the large whale carcasses will naturally decompose, with other marine life from microbes to scavengers recycling their nutrients back into the environment. In some cases, carcasses may be moved to a location more suitable for a necropsy, and we work with our partners to identify suitable locations where carcasses can then decompose. We urge the public to let this natural process continue, and keep in mind the regulations on collecting marine mammal parts. While decomposing carcasses do not pose a human health threat, beachgoers should keep children and pets away from carcasses.

What is the status of the eastern North Pacific gray whale population?

Gray whales were hunted nearly to extinction by commercial whaling. The eastern North Pacific population has since recovered, protected by international conservation measures and the Marine Mammal Protection Act in the United States. Although gray whales in the eastern North Pacific have recovered, the whales continue to face an array of modern threats. These include entanglement in fishing gear, collisions with vessels, and disturbance from underwater ocean noise. A western North Pacific population of gray whales, which summers off the Russian coast in the Okhotsk Sea, remains endangered.

Do all gray whales migrate to the Arctic?

Most eastern North Pacific gray whales migrate between the feeding grounds in Alaska and the wintering grounds in Mexico. A few hundred individuals, known as the “Pacific Coast Feeding Group,” do not travel to the Arctic and instead feed along the Pacific coast between southeast Alaska and northern California. These whales typically overwinter in Mexican waters with other eastern North Pacific gray whales.

What is the size of the Eastern North Pacific gray whale population along the west coast?

The best estimate for the number of Eastern North Pacific gray whales can be found recent here and in the most recent marine mammal stock assessment report for the species.

Where do gray whales primarily feed?

Gray whales feed primarily in the Arctic in summer, consuming sea-bottom amphipods and other organisms living in and above the sediment and in the water column. They “place their bets” during the summer/fall feeding season when they seek to consume enough food to survive the following six months, as they do not feed extensively during their migration or their winter in Mexico. The gray whales likely face the greatest nutritional stress during the northbound migration off the West Coast, when they may be reaching the limits of their fat stores. If they did not consume enough food during the spring and summer feeding season, they may not have enough nutritional stores to fuel their roundtrip migration back to the Arctic (roughly 10,000 miles). NOAA Fisheries’ West Coast Region and Southwest Fisheries Science Center monitor this situation as part of annual surveys conducted along the California Coast.          

Are there more whales dying that we do no know about? Do you find all of them?

Analysis following the last UME indicated that only 3.9–13.0 percent of all Eastern North Pacific gray whales that die in a given year are found on land and are observed and reported (Punt and Wade, 2010). 

How many gray whale UMEs have previously occurred along the west coast?

One previous UME involving Eastern North Pacific gray whales occurred between 1999-2000. This event occurred throughout the species’ range in Mexico, the United States, and Canada, with more than 650 animals stranded along the west coast of North America including 222 in the United States (Gulland et al. 2005). Some of the stranded whales were emaciated and calf production in 1999 and 2000 was less than one third of that in 1996–98. Oceanographic factors that limited food availability for gray whales were identified as likely causes of the UME, with resulting declines in survival rates of adults during this period.

What happened after the previous UME? Did the population recover?

The overall gray whale population is estimated to have declined from about 21,000 in 1997/1998 to 16,000 in 2000/2001 following the UME, and calf production dropped during 1999–2000 to less than one-third that of previous years (Punt and Wade, 2010). In the following few years, gray whale strandings declined back to pre-1999 levels, calf production increased to more typical rates, and the population rebounded to about 27,000 animals in 2015/2016 before the current downturn. The gray whale population has demonstrated its resilience in recovering from endangered status (delisted in 1994) and again following the 1999–2000 UME.

Numbers of gray whales and calf counts show hints that the decline may be slowing and the population may be starting to recover. When does NOAA end a UME?

Based on the history of the population, the lower number of strandings, and increasing calf counts, researchers are cautiously optimistic that the population will rebound again. Continued monitoring will determine when the population stabilizes and then begins to grow. As outlined by the Marine Mammal Protection Act, UMEs continue until the resulting investigation and the Working Group on Marine Mammal Unusual Mortality Events determines that its causes have been resolved or become persistent and recommends closure by NOAA.

Is this die-off event related to the UME declared for whales in Alaska a couple years ago?

To our knowledge no, the 2015–2016 Alaska and British Columbia Large Whale UME was investigated but a definitive cause was not determined. That UME also involved fin and humpback whales. Additionally, researchers think that UME may have been linked to specific unusual oceanographic/climatic conditions occurring in 2015.

Have other marine mammals or animals been affected by this die-off event?

There are two additional recent UMEs along the Pacific coast. One that recently closed involving Guadalupe fur seals and one involving ice seals, both of these events started prior to the gray whales stranding. 

What are the next steps in the investigation now that an UME has been declared?

As part of the UME investigation process, an independent team of scientists (investigative team) has been assembled to coordinate with the UME Working Group, Department of Fisheries Oceans Canada (DFO) and Mexican scientific colleagues to review the data collected and to determine next steps to help investigate the cause of the UME. The investigative team has developed an investigative plan and it may require months, or even years, of data collection, analysis, and interpretation.

What additional resources are now available to pursue the investigation, since an UME has been declared?

An UME declaration provides additional expertise from the Working Group (an international and multidisciplinary team of scientists) and stranding response partners, as well as access to extra funding through the Marine Mammal UME Contingency Fund. In addition, a detailed investigative plan is developed that may include more targeted necropsies; further testing of samples for biotoxins, bacterial or viral agents; and diagnostic pathology services. Finally, through the UME process all findings and interpretations undergo national and international scientific review.

Will you be collecting additional biological and environmental information?

Stranding network partners continue to collect and analyze samples from whales that strand in U.S. waters as needed to evaluate the situation. The Working Group decides whether additional information is needed. 

When will you have some results to share?

You can track the progress of our investigation from our Gray Whale UME webpage.

When will the UME close?

You can find more details about the UME closure process on our UME webpage.

What is the risk to humans?

Large whales are wild animals and may injure people if approached closely. 

Are there any risks to pets?

Pets should always be kept away from marine mammals, particularly diseased or dead marine mammals. 

Where can I find additional information on gray whales and other Unusual Mortality Events?

You can find more information on our gray whale webpage and our UME webpage.

What should people do if they encounter a dead whale floating in the water or stranded on the beach?

Please immediately contact your local or regional stranding network organization if you see a sick, injured, or dead whale in coastal waters or stranded on a beach:

• In California, Oregon or Washington, call the West Coast Marine Mammal Stranding Network: (866) 767-6114
• In Alaska, call the Alaska Marine Mammal Stranding Network: (877) 925-7773
• In Canada, call the British Columbia Marine Mammal Response Network (800) 465-4336
• Contact the U.S. or the Canadian Coast Guard on channel 16 or the network phone line in the United States if you observe sick, injured, or floating whale carcasses at sea
• Do not touch the whale
• Do not allow pets to approach the whale
• Observe the animal from a safe and legal distance of at least 100 yards (safe for you and the animal)

What can I do to help the investigation?

The most important step members of the public can take to assist investigators is to immediately report any sightings of live whales in distress or stranded, or dead whales. 

• In California, Oregon or Washington, call the West Coast Marine Mammal Stranding Network: (866) 767-6114
• In Alaska, call the Alaska Marine Mammal Stranding Network: (877) 925-7773
• In Canada, call the British Columbia Marine Mammal Response Network (800) 465-4336

Additionally, the public may use Pay.gov to donate to the Marine Mammal UME Contingency Fund for this or other UMEs and help cover costs incurred by the Marine Mammal Stranding Network.

What should people do if they witness harassment of a whale in the water or on the beach?

To report violations please contact NOAA’s Office of Law Enforcement at (800) 853-1964.

What is the Marine Mammal UME Contingency Fund?

MMPA section 405 (16 USC-1421d) establishes the Marine Mammal Unusual Mortality Event Contingency Fund describing its purposes and how the public can donate to the fund. According to the MMPA, the fund: “shall be available only for use by the Secretary of Commerce, in consultation with the Secretary of the Interior:

• To compensate persons for special costs incurred in acting in accordance with the contingency plan issued under section 1421c(b) of this title or under the direction of an Onsite Coordinator for an Unusual Mortality Event
• For reimbursing any stranding network participant for costs incurred in preparing and transporting tissues collected with respect to an unusual mortality event for the Tissue Bank
• For care and maintenance of marine mammal seized under section 1374(c)(2)(D) of this title”

The National Contingency Plan for Response to Unusual Marine Mammal Mortality Events outlines the types of expenses that are reimbursable under the fund and the process for requesting reimbursement.

Learn more about the Marine Mammal UME Contingency Fund

How can deposits be made into the UME Contingency Fund?

The following can be deposited into the fund:

• Amounts appropriated to the fund
• Other amounts appropriated to the Secretary for use with respect to UMEs
• Amounts received by the United States in the form of gifts, devises, and bequests under subsection (d) of section 405(d) of the MMPA

The public may use Pay.gov to donate to the Marine Mammal UME Contingency Fund for this or other UMEs and help cover costs incurred by the Marine Mammal Stranding Network.