Oyster Reintroduction in Essex with Blue Marine Foundation

Transcription

Rob Smith: Now, this podcast is being first released in November, and since there is an R in the month, if you choose, you can eat oysters. And if you do so choose, then the chances are that you will eat a pacific rock oyster rather than a native British one. And that's because over the last couple of centuries their numbers have plummeted catastrophically by over 95%. Ever since Roman times, British native oysters have been famous for their unique meaty texture and flavour.

In 1864, no fewer than 700 million oysters were eaten in London alone. They were a staple of the working man's diet, in fact. But by 1964, that number had dropped to just 3 million. And the oyster beds around the UK were damaged and depleted and often destroyed by overfishing, pollution and disease. Well, there are a few places where the traditional native oyster fisheries have managed to cling on and a couple of weeks ago, I went to one of them at Brightlingsea on the banks of the River Blackwater in Essex, to find out more about ENORI, which is the Essex Native Oyster Restoration Initiative.

The Blackwater forms part of the UK's largest marine conservation zone, along with the Crouch, Laroche and the Colne, and it covers some 284 square kilometres of estuary. It's a huge area and the ideal spot to try and boost the prospects for our native oysters. I met up with Matt Utley from the Blue Marine Foundation at Essex Wildlife Trust's Wigborough site to ask him why we were standing on a huge pile of scallop shells that had been bought from restaurants in London.

Matt Utley: So here the shell is what we call weathering, so it sits for approximately twelve months just to ensure that any residual meat that's on them sort of breaks down. There's no risk of invasive species.

Rob Smith: So these have come from the restaurant trade, haven't they?

Matt Utley: They come from restaurants, yes. So it's a byproduct of the restaurant industry. You can imagine when you had oysters in the natural environment, they would die there. The shells would remain and new oysters come and settle on those shells right as we remove them and eat them, shells then go in the bin and there's nowhere for those oysters to then come and settle and live, so we are putting all of this shell back. We've got about 40 tons here now. This year we put over 200 tonnes of shell in, along with 600 tonnes of gravel. We call it kelp, this big sort of new reef like structure for all the oysters larvae that's floating around in the water to come and settle on and grow into that next generation of oyster.

Rob Smith: So it's literally creating a new kind of a seed bed for the next generation of native oysters to grow on? Right, okay.

Matt Utley: Yeah.

Rob Smith: So how long have you actually been doing that for?

Matt Utley: So ENORI started active seabed restoration in 2019, sort of a small pilot scale in that first year, and then we've done some scale up work since then.

Each year since then, we've scaled that work up and tried to do a bigger and better area; learn each year and try and improve on what we've done.

Rob Smith: And is it starting to have an impact? Are you seeing more native oysters in the area?

Matt Utley: Yeah, so we've been monitoring it each year, going out and looking at how many oysters are settling on the material we're putting down, and we're seeing that year on year recruitment. But what we're also doing is using what we call spat collectors and we've got some of those in the field here.

Rob Smith: Sorry, what collectors?

Matt Utley: So, spat collectors. A baby oyster, when it first settles, is called a spat.

Rob Smith: Okay.

Matt Utley: And these sort of frames that we add into the water, they're lime coated plastic discs and baby oysters, the spat will settle on those discs. And it means we can really easily lift them up and cheque how many oysters are settling and how well they're doing without having to disturb the new material we've put down.

Rob Smith: Right, okay. How long does it take for a spat to become an oyster, then?

Matt Utley: Once it's settled out, it's immediately called a spat, and then very quickly, it's an oyster; juvenile oyster, then.

Rob Smith: How long does an oyster live for? I've got no idea.

Matt Utley: So an oyster left alone in healthy conditions on its own will live up to 20 years.

Rob Smith: Wow. Right, okay.

Matt Utley: But they're very slow growing. You know, it would sort of, in that time, just maybe be slightly bigger than your hand. It would only reach what we call marketable size, so about 60 millimetres in three or four years. You know, it takes them a long time to grow.

Rob Smith: Right, okay. But a fully grown one will be as big as your hand, so that's a big oyster, isn't it? That's a meal in itself.

Matt Utley: Yeah. You don't often see them that big anymore, unfortunately. You know, if they're harvested for food, then that sort of three, four, five year period is more than enough. You wouldn't want one the size of your hand on your dinner plate.

Rob Smith: But the place where you're setting up the new colche for them to grow on. That's in a conservation area, isn't it? So that's not being fished on at all? They are going to be left alone for 20 odd years?

Matt Utley: That's the plan, yeah. So it's quite a unique area we're working in here. So we're working in a marine conservation zone, which is designated for native oysters, which means it's protected for them. People can't come and fish them, but like I said, we're working with the oyster industry. There is still a fishery here on small private beds around the marine conservation zone. They're still actively working that ground and growing these oysters there, managing the stocks and looking after them. Our long term ambition is that there will be a small scale, sustainable fishery within the wider area, but not on the exact area. We're creating this new habitat that will always be closed as a voluntary no take zone. We're working with the oysterman to ensure these stocks increase and spread across the whole marine conservation zone.

Rob Smith: So, native oysters, are they significantly different to the rock oysters? Because am I right in thinking that most oysters you'll actually buy for food in the UK at the moment are rock oysters?

Matt Utley: Yes. Yeah, exactly. So you've got the native oyster, which is a European flat oyster, and a rock oyster, which is a pacific oyster. I've actually got two examples of both of these here, so you can quite clearly see they look completely different.

Rob Smith: They really do, don’t they?

Matt Utley: So the native oyster, European flat oyster, has one side that's completely flat and one that's curved, whereas the pacific oyster, or rock oyster, is very bumpy, ridgy, curvy, wavy and a bit less uniform in shape. A native oyster will tend to always look like this, whereas the rock oyster, you get quite a big difference in size and shape and sort of texture and colour.

Rob Smith: And is there an issue with sort of outcompeting the native oyster with the rock oysters? Because we know that signal crayfish are a massive issue in freshwater lakes and those kind of things. Is there a problem with having lots of rock oysters having been introduced into the UK?

Matt Utley: So it's a little bit different with oysters, so they don't directly compete with each other in the same sense that crayfish would, but they're occupying slightly different spatial niches as well. The native oyster is primarily subtidal. Pacific oyster is more intertidal.

Rob Smith: Oh okay. So, the native oyster likes to stay underwater all the time and the rock oyster doesn't mind coming out as the tide goes up.

Matt Utley: Yeah. You're starting to get some mixed beds on the sort of fringe of those two areas. And the pacific oyster is a non-native species, so it has spread and you've got these sort of new wild populations springing up that shouldn't technically be there and could be displacing or outcompeting other species. Something like a mussel bed could quite easily be overtaken by pacific oysters. But, yeah, fortunately for us, the native oyster is in that deeper water, slightly out of reach.

Rob Smith: I don't know if you're the right person to ask this, but do they taste different?

Matt Utley: So I have tried each of them and they do taste different. If you ask the oystermen here, they'll definitely say the native oyster is the nicer of the two.

Rob Smith: Far superior? Okay.

Matt Utley: It's more of a sort of meaty texture, rather than-I'm not going to describe the pacific oyster, but I'm sure most people know what an oyster texture is like.

Rob Smith: Right, okay. But the native ones?

Matt Utley: A bit firmer.

Rob Smith: Right, okay. So getting back to the kind of the nature side of stuff, then, as you're building up the kind of new reefs of the oyster beds, what else does that bring in? Does that actually have an impact on the wider environment? Are you seeing other species come in?

Matt Utley: Yeah, so it has a huge impact if you have just your standard seabed before we start doing this, reef deployment is generally where we work. Sort of quite flat, uniform, not much structure or texture there. And by adding this material and having oysters on there, you're building up this sort of complex 3D matrix. It's like a sort of mini coral reef, but with oysters, and giving sort of little spaces and gaps and areas within the oysters, between the oysters, between the bits of shell and rock, provides shelter for all manner of small marine life. Your little crabs and shrimps and amphipods all come and live in those little cracks.

Rob Smith: I’m not familiar with an amphipod. What's an amphipod?

Matt Utley: It's like a mini, mini shrimp; sort of really tiny. Okay. But they're sort of the base of a lot of the food chains, and that then draws in other species as well. So bigger fish will come in to start feeding on all this sort of base level food that's there.

Rob Smith: And you are actually able to monitor this? I mean how do you know this is going on?

Matt Utley: Yes, so as part of the project, we've been going out and monitoring the deployment, the sort of culture that we've put down, looking at species richness and species abundance.

So how many species there are, what different types of species there are, and how that's changed from what was there before, and also comparing it with areas that we haven't done any work on. So having a control area, so we can actually conclusively say what we're seeing is, because of that material we've put down.

Rob Smith: Oh, okay. And is it heading in the right direction? Are you pleased with what you're seeing?

Matt Utley: Yeah, so, I mean, within the first year, we'd started to see an increase in the number of species there and the number of animals there, so it was certainly having an immediate impact. It's a slow, long process, as I said, a good few years for an oyster to grow to five centimetres. So it's going to take a long time before we've got self-sustaining populations of oysters in this sort of really rich biodiverse area. But we think and hope it's heading in the right direction.

Rob Smith: Oh, okay. And when will you know then that it has been fully successful? I guess you just keep monitoring it and come back in? I'll come back in 20 years time and see how it's gone on and, that kind of thing?

Matt Utley: Yeah, exactly that. So we just keep monitoring it, keep doing the work, keeping tabs on how everything's going, monitoring not just the immediate area we're working in, but also the wider area. So we work with other partners that ensure [sp], Fisheries and Conservation Authority to go out and monitor oyster stocks across the whole of the Marine Conservation Zone to see A, how they're doing everywhere, but B, whether there's a sort of spill-over effect from the area we're actively restoring.

And as I said, we're working with the fishing industry as well, so the hope is, and the plan is that in that wider area from this spill-over effect, it will then enable that small scale sort of sustainable fishery to reopen. And that's enshrined in the IFCAS bylaws now, so it will allow that once the stocks have sufficiently recovered.

Rob Smith: Because obviously in Kent and as Kent Wildlife Trust, we keep a close eye on everything that's going on in the Thames and Whitstable is kind of the focus of the oyster industry in Kent. Are there lessons going to be learned from what you're doing here that can be applied in other fisheries about the place? Is that part of the project?

Matt Utley: Yeah, absolutely. So we are actively encouraging and supporting restoration projects around the UK. We're part of a number of projects. We have another project called the Wild Oysters Project, which is setting up restoration hubs up in the northeast of England and North Wales. We have another site down in The Solent setting up new oyster reefs. But we're also sharing all of our lessons learned here from Essex and these other sites with other restoration practitioners, so, actually, in a couple of weeks, we have a conference. It's called the Native Oyster Restoration Alliance.

And this is bringing together restoration practitioners, industry partners, regulators from all over Europe, bringing everyone together. Everyone shares their experiences, the work they've done, the lessons they've learned, what went well, what didn't go well, which is just as important. And just really try and learn from each other, share that knowledge. And another thing we've produced is restoration handbooks, so how-to guides on the restoration process, both the seabed side of things, engagement side of things, and what we have called native oyster nurseries, which is another sort of tool we use.

Rob Smith: So we've got a marine conservation area here which actively is protecting that, but that's very localised. How is the water being impacted by the wider issues like water quality, the actual water that's getting into the system and coming down here, and climate change? Are you starting to see differences in water temperature? Is that actually impacting what's going on with the oysters?

Matt Utley: So, native oysters are temperature dependent when it comes to their reproducing, so you need to reach a certain temperature before they'll spawn.

So you have to carefully monitor how any changes in temperature of the water will affect them. Also things like changes in PH, the salinity level of the water, all of these different things that will affect the way that an oyster works and its own sort of internal systems, whether or not it'll even survive.

Rob Smith: So we've had days in the last couple of years that have hit well over 35, 40 degrees even, which is crazy. Have you noticed that having an impact on the oyster bed?

Matt Utley: It's something that luckily, our area is subtitled in quite deep water, sort of ten-ish metres, so it's less impacted than somewhere that's in sort of shallow water. A lot of the places where the oyster industry have beds in much shallower water. There were big freezing events in the past, I believe, 1960s, a huge freezing event here, which killed a lot of oysters. And the exact same happens if it's too hot. It stresses the oysters out and it can cause them to die.

Rob Smith: Okay, and as a final thought, why do you like oysters? How did you become an oyster man?

Matt Utley: I kind of fell into oysters. I studied marine biology at university, got interested in fisheries and aquaculture, and studied pacific oysters in Southampton water. I then went and worked in aquaculture mussel farming for a couple of years and sort of developed more and more interest in shellfish.

Rob Smith: And what excites you about shellfish, then?

Matt Utley: I just think they're brilliant. They're a species, but they're also often a habitat as well and it's the sort of base layer of everything that we have in the ocean. Obviously, they have so many benefits that we've spoken about already; you know, the water filtration, the biodiversity increases. They're just a really fascinating little animal. They're not much to look at, but actually, the more you dig down into them, the more interesting they become and the more you see they actually support all manner of marine life and are so integral to the health of our ocean.

Rob Smith: Well, it's great to have a chat with somebody who's genuinely passionate about a thing that lots of people probably don't think about too much, but they are amazing little creatures. I'm looking forward to actually seeing more and more native oysters in our water as years go ahead. So, Matt, thanks ever so much for your time. It's been great to find out about the project.

Matt Utley: No problem. Great to meet you.

Rob Smith: Matt Utley from the Blue Marine Foundation there. And if you want to find out more about the work that they do, then take a look bluemarinefoundation.com. They are doing some amazing stuff around the world, working to try and protect at least 30% of the world's oceans by 2030. All good stuff. And the ENORI Project, the Essex Native Oyster Reintroduction Initiative, is, of course, partnered with the Essex Wildlife Trust and they've also obviously got loads of stuff going on all along that coastline. Many thanks to them for their help on the day. The marine conservation area itself covers all of the Blackwater, the Colne, the Crouch and Laroche River Estuaries.

And, if you like a bleak, windswept marshland filled with the sound of seabirds. And I do, because I grew up on the edge of the Dengue Marshes and misspent my youth sailing dinghies on the Crouch, then I can tell you, it really is a place well worth visiting. Go out to Brightlingsea, take a look for yourself. It's lovely.