FAQs about California Sea Lion Strandings

2017-11-22 00:38:20


According to the NOAA website there was a significant increase in the number of California sea lion pup strandings along the beaches of southern and central California (especially Santa Barbara and San Diego counties) in 2016. The numbers don’t lie: January through June 2016, California sea lion strandings are almost 2 times higher than the average stranding level for the same 6 month period, during 2003 - 2012. The graph below demonstrates the California sea pup stranding increase compared to previous years.
California Sea Lion Strandings (as of 7/1/2016)


NOAA compiled a list of commonly asked questions and resources for the public during a stranding event. While not all questions can be answered here, there is a link below that will take you directly to the NOAA page for more information.
Q: Why are the California sea lion pups stranding?
A: California sea Lions can strand for a number of reasons including injury, illness, and weather and/or ocean conditions. In 2013 the Unusual Mortality Event (UME) Investigation Team and NOAA Fisheries determined that a change in availability of sea lion prey was a likely contributor to the event. Availability of prey is very important for nursing sea lion mothers; for the pups as they begin to wean and start foraging on their own; and for the other age classes of sea lions as well. Therefore, prey availability (including amount, type, quality, and location) is one factor that we will continue to monitor in 2017.
Other potential causes for large numbers of increased strandings included infectious disease outbreaks and harmful algal blooms (HABs). Although California has been experiencing some HABs this year, we currently have no indication of disease or HABs being the cause for the current event. However, we will continue to collect the necessary samples to definitively rule out these other factors as causes of the event. As the year progresses we will continue to monitor the health of the stranded animals and partner with scientists in other specialties such as oceanography to help determine if environmental causes may be influencing the increased sea lion strandings.
Q: What did NOAA Fisheries determine to be the cause of the California sea lion strandings when the UME was initially declared in 2013?
A: The likely cause was that the mothers were unable to provide adequate milk to nourish their pups resulting in premature weaning. The exact mechanism of why this happened remains unknown and will continue to be investigated. Sea lion pups are totally dependent on their mothers for the first six months of their life and are normally weaned at about 11 months of age. If the mothers had difficulty finding food, or had to travel further offshore to find food, then the pups may have tried to feed on their own before they were able, resulting in starvation.
Q: Why was it unusual to find stranded California sea lion pups in January, February, March, and April during the Unusual Mortality Event?
A: Typically, the stranding network begins seeing stranded pups in May and June as the young of the year are weaned and begin foraging on their own. California sea lions are born in large rookeries on offshore islands along California and Baja Mexico, with almost all pups born in June each year. Pups typically remain with their mothers for the first 10-11 months of their life and become independent in May of the year after their birth. The current 2013-16 stranding event is unique because most of the strandings have occurred in the first four months of the year, much earlier and at much higher levels than the historic averages.
Q: What are the findings in stranded California sea lions in 2016?
A: At this time, the increase in strandings seems confined to California sea lion pups and yearlings. All live animals are currently being rescued and taken to stranding network centers. Consistent findings in the pups are emaciation and dehydration with most animals very underweight for their age. Long-term average female pup weight at San Miguel Island for 3-month-old pups is about 17.3 kg (~38 lbs). The majority of sea lion pups stranding in January 2016 at 7 months of age have been between 8-12 kg, highlighting the severe emaciation of these stranded pups.
Q: What is NOAA Fisheries doing to determine what is going on with all the stranded California sea lion pups?
A: NOAA Fisheries is working with scientists and network partners to monitor the pupping rookeries to try and forecast some of the increased strandings based on size and weights of the current pups on the Channel Islands. We are also utilizing information that we get from both the rehabilitated and sea lions that die to help determine what may be causing the increased strandings.
Q: What is the purpose of the Marine Mammal Stranding Network?
A: The Stranding Network is one part of NOAA Fisheries’ Marine Mammal Health and Stranding Response Program (http://www.nmfs.noaa.gov/pr/health/), a statutorily mandated program under the Marine Mammal Protection Act charged with looking at the health of wild marine mammals. The stranding network is authorized by NOAA Fisheries to respond to marine mammals in distress to help provide humane treatment and care, including euthanasia, and investigate the reason why these animals strand to better understand health and health trends of marine mammals, which frequently can informs us about the health of the entire ecosystem.
Q: How are NOAA Fisheries and the Stranding Network preparing for the increased strandings?
A: The Stranding Network facilities are getting prepared by trainings more volunteers, getting the facilities and staff geared up and ready for high numbers of animals, evaluating possible funding sources for emergency care situations, working with National Marine Mammal Stranding Program to help provided skilled staff members and veterinarians to network facilities to cover shortages, and increasing the public’s knowledge on the “do’s and don’ts” for dealing with marine mammals on the beach during this very busy time.
Q: What should people do if they encounter a sick California sea lion on the beach?
A: Please contact your local stranding network or local authorities to report a live or dead stranded sea lion.
Do not touch the sea lion.
Don’t allow pets to approach the sea lion.
Observe the animal from a safe distance (safe for you and the animal)
Sick or dead marine mammals should be reported to the stranding network agencies listed below.
Q: What are the names of the Stranding Network rehabilitation facilities caring for the stranded California sea lion pups in California during this event?
San Diego County Sea World Rescue 800-541-7325
Orange County Pacific Marine Mammal Center 949-494-3050
LA County Marine Mammal Care Center at Fort McArthur 310-548-5677
Malibu City Limits California Wildlife Center 310-4589453
Santa Barbara & Ventura Channel Islands Marine and Wildlife Institute 805-567-1505
San Luis Obispo, Monterey, Santa Cruz, San Francisco, Marin, Sonoma, & Mendocino Counties The Marine Mammal Center 415-289-7350
Del Norte & Humboldt Counties Northcoast Marine Mammal Center 707-951-4722
Additional Information about California Sea Lions and Unusual Mortality Events:
NOAA WEBSITE