In a laboratory lined with dozens of 20-gallon fish tanks at the University of Rhode Island’s Narragansett Bay Campus, eco-physiologist Coleen Suckling is raising Atlantic purple sea urchins to determine whether the Ocean State might benefit from establishing hatcheries or aquaculture facilities for growing the spiny marine creatures.
Sea urchins are a popular delicacy in Japan and at sushi restaurants around the world, with an annual economic value of about $175 million. Most of those sales come from red urchins and purple urchins harvested in California, Alaska and British Columbia and green urchins from Maine and the Canadian Maritimes. But little is known about Atlantic purple urchins, which are a common sight in Rhode Island waters, and whether they could capture a portion of the urchin market.
That’s where Suckling comes in. An assistant professor of sustainable aquaculture, she is conducting studies to determine whether local urchins could be profitably raised and sold. “Some urchin species might not be very tasty, or maybe they don’t grow fast enough to make it profitable,” she said. “There are still lots of questions we need to answer about the Atlantic purple sea urchin. The key thing is, can we make them marketable.”
Sea urchins crawl around on the seafloor down to about 500 feet, where they consume algae and other tiny marine organisms. Suckling calls them “underwater gardeners” for their ability to shape the habitat in which they live. Their voracious appetite enables them to keep algae from growing out of control, but if the urchins are too successful, they could remove so much algae that other algae-eating creatures won’t have enough to eat.
Based on her studies so far, Suckling knows that sea urchins are resilient to the changing climate. She said they have a remarkable ability to adjust their physiology to rapidly acclimate to changing temperature, salinity and acidity conditions. “They’re generally good at coping with climate change,” she said. “That means they have good potential for commercial harvest.” In a separate study, she also found that urchins are able to cope with microplastics in the marine environment by using tiny appendages that look like microscopic jaws to pick off particles of plastic from their bodies.
Are the edible parts of Atlantic purple sea urchins appealing enough to compete with established urchin species? That’s the big question Suckling is tackling next.
The edible part of the sea urchin is its gonad tissue – which chefs refer to as roe or uni and Suckling describes as tasting “like what you imagine a clean ocean smells like.” This tissue must be large, firm, and a bright pumpkin or lemon color to fetch the highest prices.
Most wild urchins have unimpressive gonads, however, so commercial harvesters collect wild-caught urchins and feed them what Suckling calls “a finishing diet” in cages in the open water for a few months until their gonads grow larger and develop a bright coloration. So Suckling has partnered with Urchinomics, a company that is pioneering urchin ranching around the world. She is testing the company’s sea urchin feed to see if Rhode Island urchins will eat it and, as a result, become commercially appealing.
“If they become marketable, then it opens up a whole interesting range of potential options,” she said. “Under future climate conditions, there may be a need to diversity what we produce in the seafood sector. And since urchins are good at coping with acidification, this could be a good opportunity here in Rhode Island to exploit sea urchins.”
During the first round of testing last winter, Suckling’s students fed the urchins a variety of commercially-available feeds, including the product made by Urchinomics. And while the results appeared promising – at least in producing larger, firmer tissue – the pandemic delayed the final analysis. Additional tests will be conducted later in the year, and Suckling will share her results with the company to assess the marketability of local urchins.
Assuming the results are positive, how would a local sea urchin industry look? Suckling said it’s still too early to tell. Much would depend on the willingness of the Rhode Island Coastal Resources Management Council to support such an endeavor and whether local aquaculturists would be interested in raising urchins. Suckling has already received inquiries from local oyster farmers, so the second question may already be answered.
Based on how urchin farming works elsewhere, though, hatcheries may be established on land to breed urchins so wild urchins are not depleted from the ocean. And adult urchins may be fed their finishing diet in cages in coastal waters, similar to some existing shellfish aquaculture operations, or in land-based tanks.
“There are still too many questions to answer before we can get anything started,” said Suckling. “How and where do we get seed [larval urchins], how easy are they to rear, is it cost effective to do it, and most importantly, how long does it take to grow them to market size. If it takes too long, it may not be worth it.
“For now, though, we’re just taking the first steps to see if it’s worth the effort to answer the rest of these questions,” she added.