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Strange Tides – An Upheaval in the California Coastal Food Web

The coastal waters of California are strikingly diverse and rich with sea life. Currents, winds, and upwelling combine to create a singularly unique set of ecosystems, each very separate yet completely intertwined. These systems are constantly evolving and we do not yet fully understand the human impact on many of them.

That is why at the current moment, we have many amazed yet baffled scientists. Strange and dramatic events have recently been occurring along our coastline that we have been struggling to understand. Some areas have seen an explosion of ocean animals, while others saw marine life wasting away from starvation. A major upheaval has occurred in the ocean food web and we have been left to speculate whether it has been caused by human or it is simply the curious result of a natural ocean cycle.

Whale watching vessels out of Monterey were bringing back jolly customers raving about the amazing creatures they witnessed. Fleets of dolphins were showing off their acrobatics; the normally elusive killer whales were seen frolicking in the waves; massive numbers of brown pelicans have been swarming San Francisco Bay; the usual sighting of 2-3 humpback whales shot up to 50 sighted per trip; a grand total of 364 grey whales were seen migrating, exactly doubling the count of 182 from last year. Even blue whales, the absolute giants of the sea, were gracing us in abundance. It’s been a circus of marine life that has made naturalists and wildlife enthusiasts quite happy.

It was a very different story earlier in the year and further south. Hundreds of emaciated sea lions were stranding on beaches and dying from starvation. Where they usually have a thick layer of insulating subcutaneous blubber, only bones thinly wrapped with skin could be seen. The rash of skinny sea lions did not exhibit any symptoms other than hunger, ruling out biotoxins and pollution. Pelicans and other seabirds seemed unnaturally thin as well.

Something is quite obviously out of balance. Whenever there are an unusually high or low number of marine organisms in one area then we must turn to examine their food supply. What scientists found there has very interesting implications.

The starving sea lions were missing a very important element in their diet – sardines. The population of this little forage fish crashed on an epic scale last year, leaving their normal predators starving. Sardine fishermen were coming up with empty lures and minuscule catches, forced to rely on squid to make a living. The last time the herring population crashed this dramatically was in the 1950s, when the canneries of Cannery Row in Monterey were forced to shut their doors after the fishermen could no longer find any more sardines. It would take another 40 years before the sardines rebounded to the point where they could be fished again.

The exact opposite occurred with the anchovy population last year – they grew exponentially, sparking a feeding frenzy among the beasts of the ocean. Visitors walking along the beaches of Monterey would have noticed the water shimmering with the millions of tiny little silver bodies of the forage fish. And they certainly would have noticed the dozens of humpbacks lunge feeding and breaching just a feet away from kayakers, surfers, and boats. The Great Anchovy Boom of 2013 took place right in Monterey, the site of the Great Sardine Bust of the 1950s, just months after a similar sardine bust happened in southern California.

It’s tempting for us to blame human influence when a dramatic event happens in nature that we don’t understand – overfishing, climate change, or ocean acidification could be the culprits. But the answer may not be so straightforward. Both anchovies and sardines are short-lived and prolific forage fish. They are tiny but packed with nutrients, forming the core of the ocean food web, along with squid and other forage fish. History shows us they have wildly unpredictable population numbers and are very susceptible to environmental conditions.

In 2003 the Monterey Bay Aquarium Research Institute led a study that looked at 100 years of data on physical oceanography, marine biology, and meteorology to determine natural cycles that take place in the Pacific Ocean. They found that sardines and anchovies have “regimes” in which they oscillate with each other. It’s a curious dance of life and death – when one booms, the other busts. Fisheries in Japan and Peru both follow parallel trends as California, leading one to draw the conclusion that there is some ocean-wide process determining the dance.

The trends they found showed that sardine and anchovy regimes alternate every 25 years or so, with the most recent shift in the 1990s – roughly 25 years ago. The shifts are due to changing ocean conditions that we have termed the Pacific Decadal Oscillation (PDO), which is similar to El Niño in terms of Pacific climate change, but it is much more long-lived rather than changing year to year. The scientists concluded that the changing conditions somehow prompt the sardine-anchovy regime trade off. Though why the populations have to trade off is uncertain – most likely it is competition for food and space. Does one population grow and push out the other, or does it take the place of an already crashing regime? And why did it happen last year in such a dramatic fashion along the West Coast? These are still unanswered questions.

This research is, of course, not without controversy. It will take many more years of studying ocean conditions and anchovy and sardine populations in order for us to fully understand what this actually means. There could be a combination of factors causing these changes, natural and/or human-related. Populations of forage fish are affected by numerous things including predator-prey relationships, ecosystem structures, overfishing, pollution, etc. It’s pretty tough to narrow it down to just one factor. It is, however, a tiny bit reassuring to be reminded that humans are not the only great force on the planet. Nature is quite forceful as well.

Our oceans are a web of complexity, a puzzle that we will probably never be able to fully put together. Part of the beauty of nature is that it still holds many secrets. Join us in respecting nature with sustainable seafood from Pucci Foods.

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