Stranded sea lion pups fall victim to California's 'ocean deserts'
Thousands of young sea lions are being found ashore, as those concerned about climate change and animal welfare speculate on the state’s changing ecosystem
The waters of the Pacific off the coast of California are a clear, shimmering blue today, so transparent it’s possible to see the sandy bottom below.
Viewing the ocean from the state’s famous craggy headlands, it’s impossible to know that the ocean’s unusual clarity is hiding a cruel beauty: clear water is a sign that the ocean is turning into a desert, and the chain reaction that causes that bitter clarity is perhaps most obvious on the beaches of the Golden State, where thousands of emaciated sea lion pups are stranded.
Sea lions are a ubiquitous part of the Californian landscape – they’re up and down beaches, piers and wharfs, with an overall population estimated at around 300,000. They have the Marine Mammal Protection Act of 1972 to thank for their existence, passed by Congress in response to concerns about dwindling populations of marine mammals, including sea lions.
Now, the familiar creatures have become victims of their own success, with some arguing that their population may have reached natural capacity, and others blaming it on changing environmental conditions in California.
Over the last three years, the National Oceanic and Atmospheric Administration (NOAA) has noticed a growing number of strandings on the beaches of California and up into the Pacific north-west. In 2013, 1,171 sea lions were stranded, and 2,700 have already stranded in 2015 – a sign that something is seriously wrong, as pups don’t normally wind up on their own until later in the spring and early summer.
The problem, explains Justin Viezbicke of NOAA, is those crystal-clear waters. “The main contributing factor that we’re looking at right now and talking about with the biologists and climatologists on the Channel Islands [a major sea lion rookery] is the lack of upwelling. We haven’t had the strong north winds that drive the currents that create it, and because it hasn’t materialized – it’s moved the prey further and deeper from the moms that are foraging.”
Marine upwelling is an important ecological phenomenon. Coastal winds act to drive surface water away, forcing dense, cold water from the ocean floor to bubble up, carrying a rich load of nutrients with it. Those nutrients feed animals and plants up and down the food chain, and they’re what makes California so ecologically diverse.
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In an environment without easily accessible nutrients, sea lions are forced to forage farther afield to find food for their pups, and the results can be fatal. Mothers may be gone for up to a week, leaving pups to strike out on their own in search of food, with many arriving on shore.
Two particular northern California pups have attracted the attention of the news in recent weeks: San Francisco’s “Rubbish”, who turned up in the Marina district after already being rehabilitated once, and an unnamed pup who hitched a ride in a Mendocino County sheriff’s vehicle when he was discovered too far inland to make his way to the ocean on his own.
The strandings are beginning to overwhelm rescue centers, which aren’t accustomed to handling this many distressed animals at once. Viezbicke explains that organizations are forced to triage pups, leaving some on the beach under supervision if they appear healthy enough, bringing others in for rehabilitation, and humanely euthanizing those who are unlikely to survive.
For those concerned about animal welfare, the thought of thousands of distressed pups is alarming, but Viezbicke sees it as a normal part of the cycle of nature, and notes that the climatologists studying the upwelling issue have yet to see evidence that climate change is involved. This is simply a localized, cyclical phenomenon, but one that has become more prominent thanks to media coverage of the issue.
He highlights the fact that though the strandings are upsetting to witnesses, they represent a huge success story for the Marine Mammal Protection Act, illustrating that the sea lion population is booming despite the strandings, which represent less than 2% of the population.
“When you go to the shore in California, there are a lot of animals out there. You need to know when you go to the shore that you will see something alive and possibly something dead,” he says. “In the big picture, everything is OK. You need to survive to pass those genes on, and that’s how we continue to have healthy animals. The strongest ones survive and the weakest ones don’t.”
Seeing the weakest dying on the shores of California in headlines across the state is troubling, but nature isn’t always kind. NOAA continues to study the situation for indicators of deeper underlying problems like algal blooms or infectious disease, and the agency, along with the sea lions, is waiting for the state’s oceanic desert to bloom with life again.
http://www.theguardian.com/environment/2015/may/08/california-stranded-sea-lions-pacific-ocean
