Frequent Questions: 2013-2016 California Sea Lion Unusual Mortality Event

Why are you closing the Unusual Mortality Event?

The conditions under which the UME was declared are no longer occurring. Scientists are no longer documenting a marked increase in strandings. The team of scientists who investigated this UME determined the cause of the UME was attributed to malnutrition in juvenile sea lions due to ecological factors causing prey shifts.

How widespread was this Unusual Mortality Event?

Increased strandings of juvenile California sea lions were observed along the entire California coastline, but predominantly clustered in Central and Southern California counties.

What are the dates for this UME? How many California sea lions are included in this UME?

The UME was defined as occurring from January 1, 2013 to September 30, 2016, with peak strandings occurring between January 1, 2013 and June 30, 2016.  The total strandings included 8,122 juvenile California sea lions documented, with 93% stranding alive (n=7,587, of which 3,418 were released after rehabilitation) and 7% (n=531) stranded dead.

What do scientists believe is the most likely cause of this UME?

After analyzing various potential causes based on available data, scientists say the most likely cause of this UME was attributed to malnutrition in juvenile sea lions due to ecological factors causing prey shifts.  Several factors were identified that impacted the ability of nursing females and young sea lions to acquire adequate nutrition for successful pup rearing by females and successful growth of juveniles. These factors included shifts in distribution, abundance and/or quality of sea lion prey items around the Channel Island rookeries during critical sea lion life history events (nursing by adult females, and transitioning from milk to prey by young sea lions). These prey shifts were most likely driven by unusual oceanographic conditions at the time due to the “Warm Water Blob” and El Niño.

What happened to the prey fish in 2013?

There was decreased anchovy and sardine recruitment in the fall of 2012 and winter of 2013.

The Fisheries Ecology Division (FED) of the NMFS Southwest Fisheries Science Center

(SWFSC) conducted an annual mid-water trawl survey that targets pelagic juvenile rockfish, and the micronekton forage assemblage (including other juvenile fishes, krill, coastal pelagic species, and mesopelagic species). Mid-water trawl surveys found decreases in sardines and anchovies over the last several years including 2012. Adult female California sea lions primarily forage on hake, squid, juvenile rockfish, sardines and anchovies. The disappearance of high energy anchovy and sardines in the female foraging areas during the lactation and fetal development stages during September to March 2013 may have led to the females being physiologically/nutritionally stressed leading to decreased or ceased lactation resulting in low weaning weights of their pups.

What unusual ocean conditions occurred in 2013-2016?

Extreme drought in California combined with geopotential height anomalies started in 2013. Anomalous warm sea surface temperatures (SST) started offshore in the winter of 2013-2014 and moved into coastal waters in the middle of 2014 and persisted until March 2015 (“The Warm Water Blob”). Warm SST was further enhanced by the El Niño that occurred in 2015-2016 with some of the warmest tropical SST anomalies reported in November of 2015. These atmospheric and oceanographic processes had detrimental impacts on multiple taxa within the California current including krill, Dungeness crab, salmon, seabirds, sea lions, and whales.

What did scientists test for? What did they find?

The majority of cases between 2013 and 2016 were early weaned sea lion pups (6 to 9 months of age) or yearlings (1-2 years old) in poor body condition including severe emaciation. No single pathogen was consistently detected in rehabilitated or free-ranging pups. All pups tested were negative for morbillivirus. Secondary common concurrent infections that occurred in the malnourished animals included bacterial or lungworm-associated pneumonia, calicivirus, herpesvirus, adenovirus and astrovirus infections, and gastrointestinal parasites including roundworms, tapeworms and thorny-headed worms.

What types of marine mammals did this UME effect?

This event involved juvenile (<2 years of age) California sea lions.

What is next now that the Unusual Mortality Event has been closed?

Scientists plan to continue post-UME monitoring of California sea lions off California for the next several years. Expected steps include continued monitoring of California sea lion strandings on an annual basis, including assessing body condition, age class and timing of sea lion strandings as well as conducting necropsies on a subset of animals to monitor for any changes in exposure to infectious disease.

Where can I find additional information on bottlenose dolphins and other Unusual Mortality Events?

You can find more information on our California sea lion and UME webpages.

What should people do if they encounter a dead floating or stranded California sea lion on the beach?

Please immediately contact your local stranding network or local authorities to report a live or dead stranded sea lion:

• In California, Oregon or Washington, call the West Coast Marine Mammal Stranding Network: 1-866-767-6114.

What should people do if they witness harassment or any marine mammal violation 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 UME Contingency Fund?

MMPA section 405 (16 USC-1421d) establishes the Marine Mammal Unusual Mortality Event 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 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 UME Contingency Fund for this or other UMEs and help cover costs incurred by the Marine Mammal Stranding Network.