Sea Urchin Spotlight: Exploring the science and art of culturing these spiny echinoderms

Corinne

Welcome back to Salty talks. I'm Corinne Newfie, the communications specialist at the Aquaculture Research Institute, and today we are talking about sea urchins. So I went up to CCAR, the center for Cooperative Aquaculture Research, last month to talk with Steve Eddie and Luz Coxon about some of the research that they've both been working on up there.

Steve

r of CCAR and have been since: 2016

Luz

I'm Luz Coxon, and I'm a research associate here at CCAR. I have been working with Sears since for the last five years or so, and before that, I was working with Fish and started with Tilapia. I'm a veterinarian in animal science and also have a master's degree in aquaculture. Since I joined the CCAR now, almost 13 years ago, been doing pretty much a little bit of fish here and then, but I said the last five years or so, I've been working with Saber Chins. And trying to produce them and enjoying the work. Visual Creatures

Corinne

when I think of seafood in Maine, I think of oysters. Lobsters sometimes clams, but rarely do sea urchins enter my mind. In fact, before doing some background research for this podcast, I wasn't actually aware that there was much of a market here for these animals. So I asked Stephen Lewis how these creatures fit into the larger seafood culture in Maine and New England.

Steve

e. And so it peaked in, like,: 1996

Corinne

I've never seen sea urchin in any seafood markets that I shop at, so I was curious about what the market's actually like here. I love to order it when I'm out for sushi, but that's about the only place that I've ever seen it, which it sounds like is most people's experiences.

Steve

Sushi restaurants is where most people encounter sea urchin row. And so they're eating the uni, which is the processed row from the sea urchin. Chances are pretty good that came from Japan. And so what's happening is the processors here there's only two left now, are shipping their trays of uni over to Japan. They get auctioned off. I've actually visited that auction. It's at the Ski Chi Fish Market in Tokyo. So it's a room full of boxes of sea urchin row from all over the place, including the US. So most of that ends up for Japanese restaurants, but some of that uni gets shipped back over to the United States. For all the sushi restaurants that we have here, some of that might be from Maine, or some of it might be from Japan or other places.

Corinne

Maybe it's because I love to eat uni. But the first thing that comes to my mind when I think of sea urchins is definitely food. But that wasn't the original goal. When sea urchin aquaculture started in Maine, it was more for restoration purposes in areas where sea urchins used to be abundant.

Steve

Thefishermen were very interested in receding areas that had been wiped out where there were no longer sea urchins. And so that's what the Japanese approach was for a long time. They established the first hatcheries in Japan for sea urchins. They had, like, six species that they fish for over there. They established hatcheries for those in the all of those seed urchins were planted back out for restoration. And that was what people were most interested in here. It wasn't really thought to be feasible to farm them. Like you might farm salmon or something in more recent years, is people have looked at that aspect, farming them right from the hatchery all the way through in captivity to market. And that's what a lot of our research here has been focusedon.

Corinne

So in Maine, is anyone currently farming sea urchins to market right now, or is it purely research based?

Steve

There's a couple of companies doing it at, I'd say, a beginning stage. One of our oldest industry partners has a lease site in Lemoyne. It's like a three acre bottom lease, and he grows oysters there and he also grows sea or there. His market is a little different. It's not the traditional food market. It's more for the research market. That's what his company specializes in. So I think he has harvested some merchants from that site and sold them into that market. But we are also working with a couple of other companies that are really at the very beginning stages of growing these animals, either with seaweed or with shellfish. And I don't believe they're at the point now where they've been able to market any of their

Corinne

The method of actually growing these animals is something new to me. And so I asked Louis Cogson, our sea urchin culture expert, to describe how this is done for you all.

Luz

Normally the thing we do is just to grab the or just ask one of the divers helping us to get the brew stock into from the ocean and then to the bigger size sea urchins and bring it over. Here to sea car and acclimate them to spawning time and to assure and then we will put it in our systems with normal water from the bay. We're going to feed them pretty much heavily until they develop all the garnets and is going to be ready to spawn. Normally we'll be timing, the timing was going to be early spring, late March into April. And then after that we collect the sea urchins from our tanks, put it on a table and do the spawning. Because the sea urchins, we cannot identify them, male, females, from seeing them, we have to inject them, induce the spawning and we use some potassium chloride for that. And then we just put them upside down, inject them and then back to seed to release. And then normally five minutes after the injection, they will start releasing and it's going to be a beautiful orange color. And those are the eggs. And the other ones, it's going to be the mouth, it's going to be a creamy white, thick melt. And then after that we're going just to be doing the fertilization. It's going to be also everything, all the things going to be manual. And then we're going to be kind of providing the miracle of life to them because we're going to put everything together, eggs and milk. We'll put those in the incubators. Incubator is going to be for about 48 hours, 24 hours we're going to be hatching, but we let them another 24 hours until they get to 1s that. And then after that we rinse them off, put it in conical tanks, they're going to be about two or 30 liters and then we're going to start another step. That is called the early development stage.

Corinne

Okay. So turns out there's a lot more steps to urchin culture than I thought. So to sum that up for you, divers are going out. They are collecting brood stock from the ocean, bringing it back to seacar to acclimate. Once they've been fed and the go nuts have developed, it's now time for spawning. So the urchins will either produce eggs or milk, depending on their sex. And the eggs and milk will then be mixed and placed into incubators.

Luz

That'she beginning. Then we started with a neck with a sperm and then there's going to be the decided fertilization. And after that there's going to be life. And after that they're going to become larvae. And then the larvae is going to be going through so many stages about until they get competent in larvae that you don't see at that point, you don't identify a fiorchin. It's going to be pure and then it's going to be different stages until they got another organella. That is going to be the rudiment that also are going to be progressing in time when they're going to get ready to another stage for the alarm. That is going to be the settlement in the metamorphosis. And when you call that time now, 1s juvenile in a SEOC is going to become and it's going to take about 25 days to get to that stage. But in between you don't see a sergeant as per se 1s as we knowthem.

Corinne

So are these little things just swimming around in the water at this point?

Luz

Yes, they are microscopic and normally we have to check them to see the development every day. And we feed them actually, that's the reason to provide the development. They have to be fed and we use micrology for that and then we fed them every day. And also we have to maintain the quality of the water. That means to do watered changes until they get to the point that's going to be harvest. Do the sediment that is going to be attaching to the surface, do the metamorphosis. That means it's coming up inside out, shading all the arms and then attaching to the surface and become a little serious with his spine. It's a little tiny wamp, but still he's in a microscopic stage.

Corinne

So after fertilization the larval stage and finally this juvenile stage, we can finally start to see these little things. Once these urchins attach to a surface, they then look like these little pincushions or hedgehog type creatures, whatever most of us picture. When thinking of sea urchins, though, Steve definitely had a better way to describe these animals.

Steve

So when they're larvae, they look like under the microscope, they look like a bell jar with these legs dangling down, appendages.

Corinne

So kind of like a jellyfish or something?

Steve

Kind of like a jellyfish, yeah. Only the trunk of the body is kind of elongated. It's not flattened like a jellyfish is, or maybe like a tiny little octopus, something like that. And then what Louis is referring to, when they go through metamorphosis and they're competent, the body is sort of transparent. And you can see this little shell, this little oval thing developing alongside the stomach inside of the sea urchin larvae, which, by the way, is called an ekinoplutius, if you want some technical jargon. And so Lou's monitors that really carefully, and she waits until just the right time to move them out of the larvae tanks into another set of tanks where they go through this metamorphosis and they sort of shed that outer body, and all that's left is that inner portion, which is called the rudiment. At that point, it's literally what they call a pinhead sea urchin because they're like the size of a pinhead, and it's got the tiny little spines and the little tube feet. You can see all of this under the microscope.

Corinne

Luz had mentioned to me that the brood stock, the sea urchins that were collected and brought back to seacar were eating kelp. But I wanted to know what these little, tiny baby sea urchins were eating

Luz

for the little ones, for the larvae after that, it's going to be microalgae. Okay? Different kinds of microalgae. Normally we use here turtlesta. 1s The rodimonas or catastrophes in different types. But we combine these to try to provide a full range of nutrients for them. But they have so microscopic, which is just even smaller than the seorchin. And then we fed them with at that stage when they are ready to settlement and do the amorphouss we have been before that acclimated some plates or a structure or just to be able to produce just they're going to have biofilm and then the little new is metamorphite, just metamorphosis. Sergeants will be able to eat on that biofilm. And then when the mouth is going to develop now, they're going to be start grazing around and then we use the same flake and then also we use alva. And when they are little bigger than that, like two or three months after, we start putting some kelp in the small tanks as well, just to motivate them, just to eat. But normally the basic diet is going to be kelp and microbie. All the dolls, they really enjoy those kinds.

Corinne

Since kelp seemed to be something that urchins like, it made me think of a practice that I have heard about before, which is farming sea urchins in tandem with kelp.

Luz

Definitely. That is one of the ideas right now. After the booming of the farm kelp farming, they saw an opportunity just to have that integrated. And then now we have one of the farmers, she is doing just really well because he has a kale farm and also she's having sea urchins and producing sea urchins as well in thehatchery. Is this up in Frenchman Bay? Is that it is in Goodsboro. Okay.

Corinne

Is that springtime?

Luz

Yeah, springtime.

Steve

Yeah. Just like any farmer, the seaweed farmers have to sometimes thin their crop. And so if you're growing sea urchins at the same place, you can just feed the thinnings to the urchins. And then sometimes too they'll get seaweed that has barnacles on it or holes in it or just isn't the best grade for what they're trying to market. And the sea urchins will eat that too. Sea urchins will eat just about anything. So in Japan, they brace them on cabbages, they'll eat carrots. 1s The biofilm that lose refers to another word for that is scuz. So just that fuzzy stuff that grows on peers and yeah, anything you leave in the water for too long, they'll feed on that. They'll feed on detritus. Are they herbivores or they eat barnacles and little snails and eggs and anything. Pretty much they're not very choosy, but they love kelp. That's their preferred diet. And that's been a problem in some places. When sea urchin populations get out of hand, they can totally wipe out

Corinne

stepping away from sea urchin diet for a second. The Northeast Regional Aquaculture Center, or NRAC, funds a lot of projects and are currently funding a project that Luz is working on with the University of Rhode Island and Colleen Suckling. So I asked Lou's to tell us a little bit about that project.

Luz

They are looking to enhance in their hatchery techniques just to be able to produce as many larvae as possible. That's just search engines and drew and else possible for farmers that are going to be able to integrate in different systems. And then oysters, scallops kelp.

Corinne

So by looking into hatchery techniques, do you mean looking into different feed formulations or like water temperature, water quality? All of the above? None of the above?

Luz

All of the above. Actually, yes. We're going to try just to figure out the more efficient and more affordable way to produce massive amount of 1s join out SEO for farmers. And because the hatchery part of it is quite intense and labor intensive, the thing we're trying to do is to use different techniques and then modify systems and then to see where it's going to be the more efficient one, 1s the one that we're using right now, is to try to implement plant. Imagine the PVR. It is just a huge like a robot that is going to be producing microalgae by itself. And the only thing just to program the system and they're going just to be adding nutrients and CO2 to the microalgae to have this quality microalgae available because that part of the process is quite labor intensive. And that is the thing that's going to be also modifying systems with filtration air and the water quality in water exchanges to make sure that it's going to be free of bacteria. Because the larvae at that stage is quite sensitive for bacteria. Blooms, and then we'll kill them and they'll get to start the process has to start over again. And it's quite intense, the hatchery process through the nursery, when the sea urchins are large enough to put on the bottom or to put into an oyster cage or whatever, is pretty lengthy. It's like six months.

Steve

other years we produce maybe: 2000

Corinne

So is an overall end goal here, then, to be able to have a domestic supply of seed stock for urchin culture?

Luz

They for me, that is the goal of CCAR

Corinne

So earlier, Steve had mentioned oyster cages as being a means of culture method, and I asked him if there were any other ways that people were doing this or if that was the most common way

Steve

In Japan, there's been some work growing them in tanks all the way to market size. There was a fellow in Ireland that for quite a few years was growing them in tanks for part of their life cycle and then putting them out into tide pools and then harvesting them from those. We've looked at tank aquaculture here. That was one of the projects we had a few years ago. It's expensive, but the upside is you get really good survival and faster growth. So maybe it's feasible. 1s Another approach is just to find a lease site, a good lease site, and put them on bottom and let them free range and then go back in three or four years and hope they're still there and grown.

Corinne

Does that is predation or like because they're also not stagnant animals. Like they're definitely they move around. Right? So if is predation or I don't know, I guess I don't know how far fast a sea urchin moves, but

Steve

over a couple of years or even a year, they can move quite a long ways. So yes, they can leave your leaf site if they don't like it there. So that's part of the trick is you have to find a site that's got a lot of kelp and maybe if it's surrounded by an area where there is no feed, they'll stay there. The other challenge is how do you prevent poaching? You can't be out there all the time and there's no spy cameras or anything. So you could have a sea urchin fisherman go fish your area where all of your urchins are. I mean, legally they're not supposed to, but they could. And then there's the predation. And so when they're small, especially major predators are green crabs and Jonah crabs. Lobsters will eat them too. When they get larger, fish like cod will eat them and probably other fish species as well. But of course there aren't as many of those as there used to be, so you have all those things working against you. But the good thing about that approach is it's really cheap. You're just putting the seed out and you don't do a thing, you don't feed them or anything. That's kind of the opposite extreme of tank farming. And then in between, we've got this approach where shellfish growers would put some urchins in with their oysters or mussels in the same cages, in the same cages, or maybe eventually move them out of those cages into separate cages, depending on where they are in their life cycle. And the reason shellfish growers are interested in that is because the sea urchins, as I said before, will eat the scuz. And so anything that grows on that shellfish cage, they can access.So they can help with biofouling. And whatnot biofouling, they can help keep the shellfish themselves clean. And then at the end of it, you've got this other critter that you can market. And when I was talking about marketing earlier, and I said most of it goes to Japan for uni. Some of it actually is sold directly to consumers online. You can go on the Internet and you can order live sea urchins.

Corinne

Yeah, I was looking that up the other day and was like, do I order live sea urchins?

Steve

I think for this podcast you really need to do that.

Corinne

I am tempted. I love uni. Yeah. Wow, good.

Steve

Along with the project that we have with the NRAC, we have another project that also we're working. And then it's just the American State Marine Fisheries Commission. And that program is just to compare two different ways to produce seal chains. One, it is in west bath and then they are doing cages down with three different kinds of feeding over there. That is one part of the project. And the other one is also in Lemoyne in Jordan River when we are putting different densities of sea urchins in cages to see how they're going to work. And then we are also just working with that and trying just to see which kind of the type of production and feeding plastic density will be the best to offer and suggest to farmers as well. And the third project that we're just starting on is through the USDA, S-A-R-E-I think that stands for sustainable Aquaculture or Sustainable Agricultural Research or something like that. And so in that project, we're working with shellfish growers who want to include sea urchins at their lease site. And we're going to see, for example, how many sea urchins should you put in a shellfish cage? Is it five, is it 20? How clean do they keep the cages? How fast do they grow? What's their survival like? So we're just going to try to answer some of those basic questions.

Corinne

That's interesting because I was about to ask you about stalking density for sea urchins because I was just talking with Dana Morset Seagrants about scallops and stalking density and it was so much lower compared to oysters of what I was expecting. But I would think that sea urchin aquaculture would also be a lot lower of stocking density.

Steve

They have to attach to a surface. So that means you're limited by how much surface area is in your container and you can't pack them in there so tightly that their spines are jabbing into their neighbor. So they need to have access to feed. I mean, they can kind of clamber over each other and sometimes you'll see these aggregations out in the wild where they're like literally heaped on top of each other, but that's kind of unusual and it wouldn't really work very well in aquaculture. So those are sort of some of the limiting factors. And then when you grow them with shellfish, the density will be probably pretty low because really the focus is the shellfish. And you can't pack a lot of sea urchins in with a lot of oysters or scallops or whatever. So the shellfish growers aren't going to end up with a lot of animals. But if they do this direct to consumer marketing. 1s They could potentially sell each animal for like, $5 a pop

Corinne

$5 for each sea urchin?

Steve

Yeah.

Corinne

Oh, wow.

Steve

Yep. And a market size urchin is around two inches in diameter.

Corinne

That's more than I would have thought because oysters are like a dollar each or I guess.

Steve

Yeah, it's because it's rare, right? So there's not a lot of them and there is demand. These companies that I mentioned, the processors that are selling them online, that's what they're getting.

Corinne

Because Steve and Lewis have both been working with sea urchins for quite some time, I wanted to know what both of them were particularly excited about and what their hopes for the future of sea urchin aquaculture might be.

Luz

Oh, yeah, definitely. We are so excited because 1s our goal we mentioned before is just to be able to produce in the hatchery as many seeds as possible, many juveniles as possible, and then that will open the door for so many other possible options. Shelters growers, kelp growers, and then even to final people that are going to be going down to their own cages and trying to produce them as a final crop. Because aquaculture online, aquaculture on line, inland is going to be a little more, a lot expensive because everything has to be the cycle is going to take about three or four years just to get to this market size. While they are in the ocean, they already have all the water, all the food that are going to be just to do more faster than inland. And that's so exciting for adjustment, trying to get that as many as possible and is going to be working hard for that.

Steve

For something that remains as unproven as sea urchin aquaculture is and no one in the United States is actually making any money at it that I know of, there's a surprising amount of interest. I get calls all the time about sea urchins from all over the world. People are just very intrigued by these animals. And then there is, as I mentioned, a lot of economic incentive. If you can figure it out, you could actually make some money. That uni is worth quite a lot. And then there's this market for whole live animals. And in addition to the uni market and whole live animals, there's also the possibility of using sea urchin. Rosen in Greed in Mediterranean chefs, for example, have used their species over there, paracentrodis Libidus. And there might be another one too. They take the uni and they mix it into sauces.

Corinne

Yeah, like pasta sauces and whatnot.

Steve

Yeah. And adds flavor and so. 1s We've got New York City, Boston, Toronto, Chicago, all these big cities with all these innovative chefs and, you know, fine restaurants. I think they would really be eager to have a steady, reliable source of uni that they could experiment with and create new dishes with.

Corinne

So for those of you listening that have not tried sea urchin or are intimidated, you should in the best way possible. It tastes like you have a face planted in the ocean. The uni, which is the gonad of the urchin, absorbs salt and sugar and amino acids, and it creates this trifecta of flavors that is just so good. But once again, Steve had a better description than I did.

Steve

Umami, it's from the amino acid glutamate, which the uni is high in. And so there's this, umami, flavor. There's sort of a little sweet aftertaste. And then there's some people who think, like oysters, that sea urchin rose and aphrodisiac. So there's that.

Corinne

Talking about the flavors of uni had me thinking about maroir with oysters, where an oyster is grown and what the water is like will affect the flavor of the oyster. And I wanted to know if this was similar for sea urchins, too.

Steve

Somewhat. But the real trick is the final diet that they eat before you harvest them. And so it's possible to grow sea urchins pretty quickly on something like catfish feed, which is around 20% protein. They grow pretty quickly. But then if you were to eat a sea urchin that had only been grown on catfish feed, it would taste kind of fishy, and the gonad color might be sort of brownish. There might be a little bitterness to it. So it's really important when you farm these to give them, like, a finishing diet. And kelp works really well. Dulls Irish moss, alaria, certain species of seaweed really prime the flavor. But there's also a company that's developed an artificial diet formulated diet that can do the same thing, sold under this entity called Urchinomics. And so it's only available through a special license. And the concept of erchonomics is in certain parts of the world, like in California, for example, the sea urchins have grown to such abundance that they've wiped out the kelp beds, and it's changed the ecology. And people want to restore those kelp ecosystems, but you have to remove these herbivores. And so oh. 1s They're trying to incentivize that by this concept of while you go out, you catch all of these urchins from these areas where the kelp has been wiped out and probably their go NY quality isn't very good because the kelp is all gone. They don't have anything to eat, so they're not very marketable. But you can bring them into captivity and feed them the special diet and it only takes maybe twelve weeks. And then at the end of that, you've got these urchins that have now big, plump, gorgeous gonads, nice orange gold color, got the sweet, umami flavor, and then you can sell those and then you're kind of doing two things at once. It's like economic opportunity and you're helping restore these kelp ecosystems.

Corinne

Urchinomics is a great name for that company. I love that. Luz, do you eat sea urgent?

Luz

Yes. Actually I was introduced by Steve.

Corinne

Oh, really?

Luz

Oh, back in the day, yes. We were just doing spawning at that time. They say, have you ever tried this? Like no. And you want to try? Of course. And then just crack one open. Enjoy.

Corinne

That's so awesome.

Luz

At that time, it was like a little bit too salty for me, but later on we did also a flavor test with a group student that we have in here and was done in ordinal. And 1s the trick of that saltiness was the rinsing before we eat it, and it was that sweet, creamy, really enjoyable flavor. And then really I enjoyed it and I thought it wasso good.

Corinne

I should eat uni for dinner tonight.

Luz

Yeah, Oh, one thing that I wanted to mention is we have been named our sea urchin. We are talking about our sea urchin. Is our green sea urchin native to the Gulf of Maine?

Corinne

Yeah, I should have asked you that like 40 minutes ago. Green sea urchins.

Steve

Okaylos. And Trotus Dropakiansis is the scientific name, and they're natives of the Gulf of Maine, but they're found all through the northern Atlantic, northern Pacific they're found off of a Russian coast in the Arctic. Up there they're found in Norway, so they got a pretty wide range. But the ones from the Gulf of Maine are renowned in Japan for their quality, and they're very similar to one of the preferred Japanese species

Corinne

which is

Steve

strungylos centrotis intermediates.

Corinne

That what I was going to say.

Steve

boration with us. That was in: 2005

Corinne

With all the talk of how much interest there is out there for sea urchin aquaculture and the project that Lose is working on with folks down in Rhode Island, I asked if there were other places in the US. That were also farming sea urchin, perhaps somewhere else off the coast in New England.

Steve

Well, they're cold water species, so even like if you grow them with shellfish, a lot of shellfish sites are in warmer water above maybe like 64 degrees Fahrenheit. They're not very comfortable. They really prefer centigrade around twelve to 15, which I think 15 is like 59 Fahrenheit. That's sort of the upper part of their comfort range. And so you're limited to cold water sites. So once you get south of Portland or even Camden, it starts getting kind of warm, especially now with the climate change. There used to be a commercial fishery in Massachusetts for green sea urchins that's gone. There's very few sites in Massachusetts where you could probably grow them. So yeah, it's mostly limited to the Gulf of Maine main north.

Luz

Next week we're going to be starting our season and we are going to go big that time.

Steve

ll use back in, I don't know,: 2006

Corinne

Oh, that's great

Steve

Yeah.

Corinne

And while I think that was a pretty good wrapping up point from Steve there, I just wanted to leave you all with this.

Steve

I had some chickens cross the road in front of me the other day and but why did the sea urchin cross the road

Corinne

to get to the other side?

Steve

To flatten someone's tire? I don't know.