Take a dive beneath the water along Northern California’s coast, and you will be surprised to find a carpet of purple.
This strange sight is the result of billions of sea urchin taking up residence along California’s shores over, with devastating effects on the local marine ecosystem. And it’s due to a combination of factors, primarily precipitated by manmade global warming.
The waters along the West Coast benefit from a unique interplay of currents that bring nutrient-rich cold water from the depths up the surface. While delicate, this environment is favourable for the growth of kelp forests, which provide food and shelter to countless species of fish and other marine animals, helping to maintain fish stocks and marine biodiversity.
But this important algae is being threatened by rising ocean temperatures and El Niños events, which have become more persistent over the past decade. Both phenomena disrupt the regular cycle of underwater currents, meaning that less of the nutrient-rich cold water reaches the shallows where the kelp put down roots, leading to less resilient forests that take longer to grow back.
To make matters worse, scientists have noticed an explosion in the local purple sea urchin population. While these invertebrates are a natural part of the kelp forest ecosystem, they are normally kept in check by their natural predators, the Pacific sea otter and the sunflower sea star. But both of these urchin-eating animals are experiencing threats to their existence, with the result that the urchins have been able to feed off the kelp like locusts.
While once a regular sight off the Golden State’s shores, California’s otter population was nearly wiped out due to overhunting during the 1700 and 1800s. While conservationists are working to bring back the native sea otter population, the process is a slow one, and currently the majority of otters are concentrated around a roughly 250 mile stretch of coast between Monterey Bay and Point Conception in central California.
The other urchin-hunting animal is sunflower sea star. These large starfish with upwards of twenty arms make their home in the waters of the northeast Pacific and were once common all along the Golden Coast. However, in 2013, marine biologists noticed a rapid population decline due to a combination of a deadly wasting disease and higher than average sea temperatures. As a result, the sunflower sea star has been absent from Californian waters since 2018, leading to an unprecedent growth in sea urchin numbers and a barren underwater wasteland where the kelp forests had once thrived.
And, due to a unique evolutionary quirk, the kelp forests are not able to recover unless the sea urchin are removed completely. The reason for this is that these pesky echinoderms have the ability to go into a kind of statis – for years at a time – when food is scarce, only to wake up from hibernation to start feeding again when the food returns.
The effects of this change are being felt not just by the marine life that used to call the kelp forests home, but by the fishing industry. California used to be one of the main harvesters of red abalone (an edible sea snail) and red sea urchin. But both of these industries have seen their catches shrink since the purple urchin population exploded.
With commercials divers out of the job and the local marine ecosystem in tatters, a motley gang of chefs, conservationists and private individuals have come together along the northern California coast to propose a radical solution to the purple threat – everybody should eat more sea urchin.
Sushi enthusiasts will be familiar with so-called uni sushi (which is made from sea urchin roe), but chefs around the world are trying to get creative with this oyster-like seafood. With it’s creamy texture and slightly sweet taste, sea urchin is a versatile food that can be used to add a dash of the exotic to pretty much any dish. And while they are not commonly found in supermarkets yet, anyone who lives near the coast can pick them up for the cost of an annual fishing license.
According to Ali Bouzari, culinary scientist and co-founder of Pilot R&D, “This is the rare opportunity for our gluttonous instincts to have a redemption arc. This is something where there are hundreds of thousands, if not millions more of these purple urchins than there should be. Go for it. You could harvest literally more than you could eat and honestly harvesting more than you can eat it is the responsible thing you can do. Just get them out of the water.”