"We're running out of land to produce food." "The good news is: We can get our food from somewhere else." Farming fish has been the fastest-growing
food production method in the world. But it comes with problems of its own." Diseases, nutrient pollution, and overfishing. To just name a few. "So let's go out there and see if we can fix this. How can we farm the oceans – sustainably?" To find that out, I came here: Ireland. More specifically, to the salmon
research site of the Marine Institute. It's specifically developed to farm
salmon more sustainably: Around 20,000 of them per year. At the same time, it produces three tons
of seaweed and hundreds of different shellfish. I'll tell you why later. First, let's meet the people who run the show. Frank Kane, Joanne Casserly and Neil Ruane. "So how bad are the waves out there? Am I gonna get seasick today, or?" "No, no. Today, we have a good one. We have quite a light breeze. So, it's all fine. A little bit of sunshine. It won't be strong, but no waves. So, hopefully we'll have a nice day." "These are funky trousers!" [laughs] The first thing I want to look into is the emissions associated with farming fish. "Fish farms impact the climate in two ways: You need to feed the fish and you also need the energy to run an operation like this." Then there are variables depending on how, where, and what type of fish you farm. It can be in a bay area or back on land, with closed-loop tanks like these. "This is surprisingly stable." The tiny food pellets this machine shoots into the pond are responsible for more than 70% of farmed fish emissions. And that's because of what's in them. "Smells quite fishy!" [laughs] "And what's in this?" "So, this is made from mainly fish meal with cereals and other fish oils. Fish need high-quality marine fish products within their food to supply them with omega-three fats for growth and health and their immune system. So, the primary product going into fish food would be fish meal. So would be fish either caught at sea or the
fish waste from fish factories." And catching fish means emissions. You need to burn fuel to power the fishing boats – AND you need to freeze or cool the fish once it's caught. "But there are alternatives. For example, here, they fed the salmon with fish waste instead of newly caught fish in the feed. And we do need to these alternatives because the small fish that are in this feed, are not available at large quantities in the sea anymore." Other ideas for low-emission fish feed are algae or insects. More commonly, soy is used as a substitute these days. But that's not without its problems. "A lot of it is actually coming from places like America, China,
but more controversially [from] Latin America." This is Alex Wan. He has been researching fish feed for years. "Where large areas of forest are being removed to grow soy. And this is being transported across different parts of the world and this has a lot of carbon emissions and also have a significant impact on nutrient run off and social impact as well." And then, you can look at how efficiently you're using the feed. There's the so-called Feed Conversion Rate – short FCR – to measure that. It determines how much feed is
converted into live weight by animals. Farmed fish are pretty good at this. Their FCR is between 1.0 and 2.4. For pork it's up to 5. And for beef it's up to 10. So, farmed fish need less feed to gain weight. "And that's because they're cold-blooded. So, they don't need as much energy
as we humans for example, to run their overall system. So they can devote more of this feed to growing." Getting a low FCR has to do a lot
with finding the perfect feed composition. This can reduce the fish's environmental
impact by as much as 24 percent. Along with feed, there's another big factor: The emissions produced from
the industry's energy consumption. And this really depends on where
and how you grow your fish. Let's look at salmon for example: It's bred in tanks on land – or, like
here, in open net pens in the ocean. "Ok, the world's tiniest windmill is here." "Yeah, and it works very well." "So, how much energy do you need
to supply this whole operation?" "So, here we have a small open pen fish farm system. So, requirements for energy on the site are relatively low. We have a monitoring buoy over here, which is solar-powered, for the monitoring and the communication. We have a small wind energy, and we have solar panels on top of this hood that is the power source that charges batteries for us to run the feeders and the small structures on site. And we have a large generator here if
we have to pump large volumes of water. For a seasite, this is a relatively low energy cost one. Generally, the open pen system doesn't require the same amount of energy – recirculating systems, on land systems would have a higher demand because they have to pump water around and heat water." The difference is actually huge. A US study compared the impacts, and if you keep salmon in tanks on land, your greenhouse gas emissions double. Farmed in open net pens you're
looking at 3.4 kg of CO2 per KG of salmon. And bred in tanks, you're stuck with 7 kg. "There's one effective way to get rid of these emissions: use renewable energies. If you use about 90% renewables,
you can cut the emissions of land-based systems to that of an open net-pen system like here." But the world average of renewable energy
in our mix is currently at 29 percent. So, nowhere near that. And sadly: The problems don't end there. "If you have a lot of fish in one place, you also have a lot of sh*t in one place." "And when that gets too much, things get ugly." Too much fish poop in the water can, in the worst case, lead to an algae bloom that can eradicate all fish in your farm – and tons of sea life on top! The fish basically suffocate underwater. Their excrements work like a fertilizer, so algae grow like crazy, and block out the sun. Which kills many other underwater plants. This means less oxygen is produced. And the bacteria decomposing the dead plants take up what little is left. In the end, the complete ecosystem collapses. In 2021, along the Chilean coast,
4200 tons of salmon perished like this. "For these 20,000 fish we got here, how much fish sh*t are we actually talking about?" "So based on the literature values that we have. The waste would be about 20% of say, what they are fed per day. So, on our site with our amount of fish that works out at about three kilos." That's about one ton per year. And when you overfeed the salmon, it gets even worse. But the researchers here have an idea of how to fix this. The magic word is polyculture, so growing different varieties of seafood alongside each other." "What's the kind of service that these scallops provide for this overall system?" "So, we've chosen scallops, but we also have oysters as part of our shellfish level. And they're what you would call extractive species. So, they would extract all of the particulate matter out of the water column. And how they do that is they have what we
would call a beard, and it's within the shell here, and that filters the water and takes the particulate matter out of it, and that is their food source." "So, they basically eat the sh*t?" "Basically yeah, but they would eat the other particulate that's available in the water column too. So, any zooplankton and bits of detritus or broken bits of organic matter. It's all available to them to eat as well." And because of that,
it's important where the scallops are placed. Because you want the current to bring the fish poop to your shellfish and not elsewhere. And the good thing environmentally is: the scallops don't require any additional feed. You just hang them in the water and wait for them to grow. The same goes for the next seafood that helps clean up the salmon's mess. "That's quite a bit of seaweed." [groans] More specifically: sugar kelp. "You can eat this?" "Yeah, if you want to take a little bit to try" "OK" "It smells salty, but it's actually very much like salad." "Yeah" "And nice when you forgot your lunch, right?" [laughs] It grows along the mainline that's just put in the water. It almost looks like a root system
from your regular house plant. And it grows really, really quickly. "So we are at about eight kilos a meter here." "Eight kilos a meter?!" "Yeah, this is getting to really more of the higher growth season by [this] time of the year. So, it really prefers the colder waters throughout
the winter. And around now it's putting on almost a kilo per week in terms of growth rate." "A kilo a week?! That's insane!" "Yeah, it's really fast growing plant material." In addition to the shellfish feeding on the small poop particles from the fish, the seaweed absorbs anything that's already dissolved in the water, like nitrogen and phosphorus
that can also lead to algae blooms. It's an on top extraction system that also
produces more food: seaweed. Growing all these things at the same time makes the whole farm more sustainable and productive. But to what extent can other species really
offset the impact of fish farming? "So probably averaged out overall,
including maybe the filtration rates of some of the shellfish, about 20 percent of what we're producing here in terms of salmon is being offset by the extractive species. And that's only with about four to
five hundred meters of long line out at the minute and only about
six hundred to nine hundred shellfish. So very very small quantities." A polyculture farm like this can take care of one problem: nutrient pollution. A big one yes, but other issues such as the spreading of diseases amongst farmed fish or chemical pollution with antibiotics remain. And that speaks to the crux of the matter. "We can reduce the fishes' impact, but we cannot eliminate it. Alternative feeds, polyculture, they don't solve the problem. If we wanted to do that, we need to get rid of the fish. I know it's super sad, but I mean the seaweed
didn't taste too bad after all." If you enjoyed me eating seaweed grown on fish poop, please subscribe to our channel. We post new videos every friday.
