Real Food Encyclopedia | Sea Urchin

“Creamy,” “custardy,” “the essence of the sea” are common descriptors used by sea urchin lovers. Most frequently encountered as “uni” in sushi restaurants, sea urchin is considered a delicacy by some and “not even on a dare” fare by others. The urchin’s exterior, covered in long, pointy spines, doesn’t exactly invite a diner in. But sea urchin has long rewarded intrepid diners who scissor past the threatening exterior with a silky, briny treat (spoiler alert: it’s the animal’s gonads) that is often called the “foie gras” of the ocean.

There are seven hundred known varieties of sea urchin that range in size, color and shape and can be found in waters warm and frigid all over the world. While all are edible, those found in cold waters are the meatiest and do not pose the threat of finger pricks or poisoning that the spindly, and sometimes venomous, tropical varieties can inflict. Three of the most popular culinary specimens include the purple urchin, Paracentrotus lividus found in the Mediterranean Sea and the Atlantic; the red sea urchin, Strongylocentrotus franciscanus, found in the Pacific Ocean from Baja, California to Alaska; and the green sea urchin, Strongylocentrotus droebachiensis which lives in both the Atlantic and Pacific Oceans.

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Fun Facts about Sea Urchin:

  • Sea urchins have incredibly long lives, living 50 to100 years. They reproduce early and prolifically, releasing several million eggs at a time. They are very vulnerable to predation when they are young and small. Once they reach adulthood, however, predators, other than man and sea otters, take less interest, probably because their spines become more threatening as they grow.
  • The name “urchin” is an old word for hedgehog, which sea urchins resemble.
  • Uni is considered an aphrodisiac in Japan.

What to Look for When Buying Sea Urchin

Sea urchins have a spherical shell, called the “test.” On the bottom of the sphere is the mouth, also called “Aristotle’s lantern,” which is comprised of teeth and membranes that grind and chew food. The shell is covered by tube feet and pointy spines. The tube feet provide locomotion, clean the shell, catch food and absorb oxygen. The hundreds of movable spines that help the urchin move are the urchin’s only line of defense against predators. The only parts of the urchin that are edible are the gonads, the reproductive organs that are so highly prized on the plate.

The texture of sea urchin is creamy and custardy in the beginning of the season and grows firmer and more granular as the roe develops in preparation for spawning. The urchin’s diet greatly influences the color and quality of the final product; a steady supply of kelp is best. The color can range from bright yellow to deep, vibrant orange.

Sustainability of Sea Urchin

Declining Sea Urchin Stocks

Most sea urchin is harvested by hand, a highly sustainable fishing method. Hand harvesting leads to zero by-catch, the inadvertent landing of unwanted species. And with no raking or scraping of the sea floor, it is very gentle on marine habitats.  No matter how gentle the method, however, any fishing practice becomes unsustainable when the targeted species are over-fished, and the same is true of sea urchin.

While some fisheries have regulated the harvest and protected the sea urchin population, others have not. Unfortunately, the sea urchin stock off the coast of Maine has been severely depleted. In the mid 1990s the sea urchin fishery was thriving. About 50 million tons of urchin was fished each year, and shipped mostly to Japan. Without sufficient regulatory control, this intense rate of harvest has resulted in a 90 percent reduction of the population. California also supplies a large portion of our sea urchin stock – over half of our domestic supply. While regulation has protected the fishery somewhat, such demand threatens to deplete the west coast supply if further regulation is not put in place. Canadian fisheries, on the other hand, have been well managed and enjoy an abundant and stable sea urchin population. Correspondingly, the Monterey Bay Seafood Watch advises eaters to avoid consuming urchin from Maine until stocks recover, lists Californian as a “Good Alternative,” and Canadian sea urchin as a “Best Choice.”

It is possible to reestablish urchin hatcheries, as John Chamberlain is proving in Ireland. He began a seeding project to repopulate his community’s shoreline with sea urchin, which were once abundant before heavy demand from France caused them to be overfished. His budding hatchery now successfully produces an increasing number of fine purple sea urchins that are the prize of their class to the few chefs who can get their hands on them.

Sea Urchin and Water Quality

Sea urchins are very sensitive to water conditions and are one of the first inhabitants to show signs of stress when quality decreases. Like the canary in the coal mine, they can be used as environmental indicators to sound the alarm on declining water conditions.

Sea Urchin Seasonality

The edible part of the sea urchin, the gonads, are a five-section organ that swells and shrinks in size depending on the phase of the breading season. Prior to spawning season, in the cold waters of winter, the gonads store food as energy and are at their fullest. At spawning, in the early spring, the urchin converts the contents of the gonads to reproductive cells and the roe takes on an unappealing watery texture and turns a brown or grey color. This makes November to March the prime season for enjoying cold-water urchin.

Eating Sea Urchin

Storing Sea Urchin

Although it the highest quality is reserved for fresh preparations, it can also be preserved in brine, alcohol, and/or salt and is available frozen.

Cooking Sea Urchin

Sea urchin is served in a variety of forms across many cultures. In Japanese restaurants it is often served raw, with rice, or tucked into dumplings. It’s also popular in Mediterranean cuisine where you will find sea urchin blended into saucestossed with pasta, or spread on crostini. Try sea urchin in some of these other recipes.

Sea urchin can be tricky to prep — here’s a great video that walks you through the prickly process.

Sea Urchin Nutrition

Sea urchin is rich in protein and dietary fiber, minerals (such as zinc) and Beta Carotene, which it gets from its kelp diet. It is also high in Vitamins C and A, which are usually found in dark leafy greens and winter squash. Like many fatty fish such as salmon, sea urchin is high in omega-3 fatty acids.

Because it is low on the food chain, sea urchin does not bio-accumulate toxins as apex predators, such as tuna, do. According to the Natural Resources Defense Council, sea urchin has a low mercury load.