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Endangered Fur Seals Dying on California Coast

December 01, 2015

Story at-a-glance

  • Scientists reported that 84 stranded fur seals – dead, dying, or starving – have washed up on California’s coast since January of this year
  • Fur seals, which live and breed almost exclusively on Guadalupe Island, 150 miles off the coast of Mexico, are rarely lost in this manner; 12 per year, scientists estimate
  • Only 16 of the fur seals that were rescued were able to recover and be released back to the ocean
  • Researchers are looking at ocean warming trends to explain the fur seals strandings, possibly related to food sources moving northward to cooler waters. The natural phenomenon El Niño may also be playing a part

By Dr. Becker

Fur seals, marine mammals which in the early twentieth century recovered from near extinction, have been washing up along the California coast in unprecedented numbers this year, a phenomenon the National Oceanic and Atmospheric Administration (NOAA) has declared "an unusual mortality event."

So far, scientists say 84 fur seals have been found sick or stranded, and half of them were dead. That's eight times the normal number of fur seals to be found in these conditions.

The NOAA Fisheries Office of Protected Resources reported:

"Guadalupe fur seal are stranding alive and dead and are mostly weaned pups and juveniles (one to two years old). Findings from the majority of stranded animals include malnutrition with secondary bacterial and parasitic infections.

"All live stranded Guadalupe fur seals are being rescued by local marine mammal stranding network members and undergoing long-term rehabilitation at The Marine Mammal Center in Sausalito, California or SeaWorld in San Diego, California."1

The fur seals that were still alive were so emaciated, only 16 of them survived and were able to be released back to the ocean after rehabilitation.

Nearly all of the pinnipeds (marine mammals with fins or flippers for feet, such as a seal, sea lion, or walrus) were young pups born the previous year, but at least four were adult females.

NOAA scientists, who in past years have only recorded an annual average of 12 stranded fur seals on the California coast, plan to devote more time evaluating this species for more clues about this occurrence, which coincides with similar strandings of sea lions, as well as seabirds starving in record numbers off the coasts of Oregon and Washington in recent months.

Fur Seals: A Threatened Species

Most fur seals live and breed solely on the tiny, volcanic island of Guadalupe, about 150 miles off the west coast off the Baja Peninsula, Mexico. An official from the Marine Mammal Center, where some of the animals are being cared for, said:

"While these numbers might not sound like a lot, for a threatened species it's actually a big warning sign that we need to pay attention to what's happening in our oceans."

The NOAA Fisheries Office of Protected Resources relayed the series of events that led to stricter guidelines and oversight:

"The Guadalupe fur seal was listed as threatened throughout its range on December 16, 1985 under the Endangered Species Act of 1973 and is also protected under the Marine Mammal Protection Act of 1972, as amended. In 1975, the government of Mexico declared Guadalupe Island a pinniped sanctuary. NMFS has classified the U.S. Guadalupe fur seal stock as a 'strategic' stock.

Guadalupe fur seals are non-migratory, with small populations on both San Benito Island off the coast of Mexico and on San Miguel Island off the coast of California. The population is currently around 15,000 and had been reported as increasing.

Guadalupe Fur Seals – An Under-Studied Species

Because of their inaccessible location, less is known about fur seals than any other seal species.Perhaps the first real scrutiny came after their 19th century extinction threat. NOAA notes:

"During breeding season, they are found in coastal rocky habitats and caves. Little is known about their whereabouts during the non-breeding season."

Adult, male Guadalupe fur seals are dark brown or black (the males being partially tan or dull yellow) and reach an average of seven feet long, while females are around 25 feet long. The male weighs in at around 400 pounds and the female, 110 pounds. They normally live to around 20 years of age.

These animals are singular in that they have narrow, flat heads, pointed snouts, and sleek, furred skin with noticeably more fur on the top fourth of their bodies. As NOAA describes them:

"Guadalupe fur seals are solitary, non-social animals. Males are 'polygamous' and may mate with up to 12 females during a single breeding season. Males form small territories that they defend by roaring or coughing. Breeding season is June through August. Females arriving in early June, and pups are born a few days after their arrival. A female will mate about a week after giving birth to her pup. Weaning occurs around nine months."2

Could Warming Waters Be Due to Climate Change?

A spokesperson for aforementioned Marine Mammal Center asserted that:

"These marine mammals are just the tip of the iceberg in terms of animals affected by the unusually warm water temperatures we've been seeing off the coast."

Conjecture has it that warming waters in this region of the Pacific Ocean could be the reason why fur seals are "stranding themselves." The waters there are typically 65 to 75 degrees, but some scientists believe that might be fluctuating and even rising due to climate change.

An L.A. Times article recounted an interesting trend scientists have been observing:

"Scientists are pointing to warmer waters in the eastern Pacific Ocean as a possible cause for the Guadalupe fur seal strandings. Dubbed 'the blob' by experts, an unusually warm mass of seawater that stretches along much of the West Coast has been affecting marine life and the commercial fishing industry."3

Scientists believe the higher water temperature may have instigated a chain of events, beginning with the fish that fur seals normally eat, such as smaller fish, squid, and krill, moving northward to cooler water.

Experts Say El Niño May Also Be Having an Adverse Effect

El Niño may also at least partly to blame for the fur seals movement from their customary waters, especially since NOAA experts say the weather phenomenon is "shaping up" to be the strongest one for 65 years. An Aljazeera article explained:

"El Niño is a natural phenomenon which occurs every two to seven years and lasts between six and 18 months. It manifests as a warming of the surface waters of the eastern equatorial Pacific Ocean. The current El Niño is so strong that in some areas sea surface temperatures (SSTs) are more than two degrees Celsius above the long-term average."4

Scientists around the globe watch El Niño patterns closely because of devastating effects it's had on industries and economies, and taken a toll on human life, not to mention the lives of animals on both land and water. Warmer waters than usual have wreaked havoc on the fishing industry in Peru, for instance, and caused more than the usual number of hurricanes and typhoons.

Not only does this adversely affect marine life, it also concerns the commercial fishing industry. According to Oceanworld.com:

"Every few years the pattern of air circulation of the equatorial Pacific changes in a way that affects oceanic upwelling. This weather condition is known as El Niño. During El Niño, upwelling brings up warm water with few nutrients. A serious economic consequence of El Niño is its devastating effect on the Peruvian anchoveta fisheries. Populations of fish and seabirds vanish and anchovy catches dwindle during El Niño."5

Guadalupe Island Known for Attracting Swim-with-the-Shark Aficionados

Incidentally, Guadalupe Island was in the news a few years ago because it became a haven for divers wanting to swim with Great White Sharks.6 But unfortunately, reports also say that in 2012 alone, more than 100 million sharks were killed by humans, presumably for their fins, said to be a delicacy.

And because sharks are also worth a lot of money, shark fisheries in the area are said to produce around $630 million every year. Aside from that aspect, the "ecotourism" industry around Guadalupe Island is estimated to generate $314 million annually, a number of experts expect to escalate to more than twice that number.

It's impossible to say how careful tourists are with marine life such as fur seals, sea lions, and others, but these aspects of the island's popularity may also have something to do with the fur seals' rapid decline.

Thousands of Animal Species Threatened

It's interesting that NOAA investigated a similar "unusual mortality event" involving another pinniped: large numbers of California sea lion pups washing ashore in Southern California beginning in December of 2014.7 Overfishing of sardines along the California coastline was a "likely contributor" to this ecological problem, according to EcoWatch.com.8

While NOAA reports the number of dead or stranded sea lions as leveling off, reports are still disturbing.

A number of organizations have sounded the alarm in recent decades and are doing what they can to help protect marine life and other endangered animal species. Now more than 40 years old, the Endangered Species Act9 was significant, ground-breaking legislation protecting thousands of animals and plants under threat from loss of habitat, predators – and human involvement.

While around 20 of the species on the endangered list have been removed because the threat has been alleviated, there are still more than 1,400 as much in danger of extinction as ever. Sadly, some of the animals under protection have disappeared completely.

One of those is a blue-footed diving seabird called cassin's auklets, including this one, have been washing up dead by the thousands on beaches from San Francisco to central British Columbia.10

Pinniped Viewing Opportunities

People can view seals as well as sea lions, with guidelines for both their safety as well as humans. Generally, neither is to be approached nor fed. Touching, riding, or swimming with them is definitely not recommended.

Interacting with these sometimes threatened wildlife is not only discouraged, it's illegal under the Marine Mammal Protection Act of 1972 (MMPA).11 This legislation was the first time the U.S. Congress designated protection over an ecosystem for the purpose of natural resource management and conservation.

You can get involved in the protection of seals and sea lions if you witness acts of aggression or harassment. Contact:

Southwest Region

NOAA Office of Law Enforcement
501 West Ocean Boulevard,
Suite 4300
Long Beach, CA  90802-4213

Or, call the NOAA Law Enforcement Hotline at 1-(800) 853-1964

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Sources and References

  • 1 2015 Guadalupe Fur Seal Unusual Mortality Event in California
  • 2 Guadalupe Fur Seal (Arctocephalus townsendi)
  • 3 Guadalupe Fur Seals Dying at an Alarming Rate off California Coast
  • 4 El Nino Set to be Strongest Ever
  • 5 Peruvian Fisheries and El Nino
  • 6 Shark Diving Lovers Swarm Guadalupe Island, Off the Coast of Mexico
  • 7 Thousands of Sea Lion Pups Are Washing Ashore and Dying Along the California Coast Overfishing to Blame for Sardine Shortage and Starving Sea Lions
  • 8 Overfishing to Blame for Sardine Shortage and Starving Sea Lions
  • 9 Endangered Species, Then and Now
  • 10 Mass Death of Seabirds in Western U.S. ‘Unprecedented’
  • 11 Marine Mammal Protection Act (MMPA)
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