Farmed Fish Healthier?
OmegaMatters: Episode 40
Hosts: Drs. Bill Harris & Kristina Harris Jackson
Guest: Dr. Matthew Sprague
SHOW TRANSCRIPT
Dr. Kristina Jackson:
Welcome to Omega Matters, where we talk all things omegas. I’m Kristina Jackson, this is my dad, Bill Harris, and today we have a guest from across the pond, Dr. Matthew Sprague. Matthew is a lecturer in nutrition at the Institute of Aquaculture at the University of Stirling in Scotland. Omega Quant has a special connection with the University of Stirling and their aquaculture unit because they help run our omega-3 index testing and their lab over in the UK. So we have a lot of connections and this is just a great group to work with and they have the extra bonus of they’re experts in fish and aquaculture, and we’re going to talk all about that today. Thank you so much for coming on.
Dr. Kristina Jackson:
Let’s start off with the news that you tested your omega-3 index recently. What did that look like?
Matthew Sprague:
Yeah, so it was the first time in over two years, and as I was saying previously, it was 7% two years ago, which is quite good obviously.
Dr. Kristina Jackson:
Pretty good, yeah.
Matthew Sprague:
Yeah. So I decided just to up my seafood intake and got it measured the other day, and it came out just over 10, which I think unbelievable.
Dr. Kristina Jackson:
It’s very good. It’s very, very, very good.
Matthew Sprague:
Yeah, because I’ve been obviously following your work as well and the publications, and from what I can recall, you’re suggesting it’s probably about 1.3 grams per day recommended to get over the 8%, which is a heck of a lot if you need to do that, because if you actually consider how much EPA and DHA there is in the world, there’s not enough. It’s probably about 1 million tons. I think Douglas Tucker, a retired professor, done this calculation back in 2015, and he actually came out as 1.2 million tons is what’s required if each person, 7 billion people, were consuming half a gram a day, but actually the supply is only just over 0.8, 0.9 million tons. So there’s a shortfall, and that shortfall probably equates into at least on 7 billion population, obviously the population’s 8 billion, there was probably around about 2 billion people going without any EPA and DHA in their diets. There’s just not enough. So yes.
Dr. Kristina Jackson:
Wow.
Dr. Bill Harris:
Interesting. So tell us about your diet. What fish do you eat and is it every day?
Matthew Sprague:
No, it’s not every day. The recommendations are for, two portions of fish per week of which one of those should be oily. So I normally meet this, however, I’ve kind of upped it to maybe three, maybe four portions. Now, this is where we also fall down here as well, because portion sizes vary between different countries, so I think it’s 4 ounces which is 112 grams in America, over here in the United Kingdom it’s 140 grams. So there’s a big difference there. European Food Safety Authority for Europe is 130 gram recommendation. So that’s the first pitfall here, there’s no consensus on this. Then we’ve also got the no consensus on what the recommended intake for EPA and DHA should be per day as well. So it’s a bit of a mind blower.
Dr. Bill Harris:
Yes, it is.
Dr. Kristina Jackson:
What kinds of fish are you eating three-ish times a week?
Matthew Sprague:
It can vary. Generally my only fish would be salmon and obviously that’d be farmed salmon, that’d be fine predominantly here in the UK. We do get the wild Alaskan species as well, but I generally have the farmed salmon, I suppose I have to say that being that I work.
Dr. Bill Harris:
That’s right.
Matthew Sprague:
Fish, again, well, this is the other issue in terms of portion sizes, what they sell in the supermarket, it’s not necessarily a portion, so it’s not 140 grams, it can be smaller in some instances. But yes, it’s salmon, mussels, whitefish so cod, haddock. So I’ve tried to vary up where I can. Occasionally I have mackerel, which is obviously really high in EPA and DHA. But yes, again, I think it’s all down to individual preferences. Some people don’t like the high fat content, including in salmon as well, there’s people that don’t like the high fat content, and they may occasionally, if they’re eating salmon, go for what we call the granny pieces, which are the tail piece portions, they contain less fat. That’s interesting that as well how EPA and DHA varies throughout the filet on the fish as well as between fish pieces, etc.
Dr. Kristina Jackson:
Oh my gosh.
Dr. Bill Harris:
And you don’t take any supplements, is that true?
Matthew Sprague:
No, unless there’s any supplements lying around. It’s literally precisely, “If there’s any around here, then I’ll maybe take one or two.” But no, it’s just fish intake. I don’t think I’ve had supplements for over a year. No, supplementation, as we know, yeah, supplementation really is just to supplement your diet. So I would always recommend personally to eat fish because you’re not just getting the EPA and DHA, you’re obviously getting ever nutrients, so you’re getting a rich source of protein, you’re getting your minerals, micronutrients, vitamins, etc, vitamin D. And again, these vary between different species. So like lean fish for example, really high in iodine compared to the fatty fish. Vitamin D, that’s quite variable is what I’ve been noticing as well. It’s not really correlated to fat content, even though it’s a fat soluble.
Dr. Bill Harris:
How about selenium?
Matthew Sprague:
Selenium? Well, maybe we’ll get into that later. That’s generally quite good. The issue where we come onto the farmed fish as well. So with the farmed fish, it’s pretty much identical, certainly for salmon, what we’re working in, it’s identical to what’s happened with the human population in terms of diet changes. We’ve increased the amounts of lipid, so amounts of fat that goes into the diet, and also omega-6. So there’s a big increase in omega six.
Matthew Sprague:
Now, the primary reason that we’ve done this is because fish species, the marine carnivorous fish species, so the salmon, they require EPA and DHA in their diets. So freshwater species, you can get species that actually produce EPA and DHA. So they’re much like ourselves where they can take in just 183 or or -3 alpha linoleic acid and linoleic acid 18 or -6, and convert that into EPA and DHA. However, they don’t produce large amounts, it’s very, very tiny amounts. The marine species, unfortunately, they can’t produce it. Salmon can produce a little bit, that’s a separate story, but then, again, it starts off in freshwater marine, but they require it in their diets. So these are actually EPA, DHA, essential fatty acids.
Dr. Kristina Jackson:
Oh, that’s interesting.
Dr. Bill Harris:
Not true in humans, actually.
Matthew Sprague:
Well, okay, yeah, so salmon are probably much the same in terms of the critical amounts they can make. But for human intakes, for our optimal health, no, they can’t, okay? So they don’t produce the large amounts. It comes through in the wild in the natural diet, that comes from microalgae. So microalgae are the primary producers and then everything else just accumulates and magnifies through the food chain.
Dr. Bill Harris:
So is the consumption of preformed EPA and DHA in these marine fish, is that what kind of shuts down synthesis from ALA?
Matthew Sprague:
Well, it’s probably evolutionary terms in that the marine environment is just abundant in terms of EPA and DHA, so they don’t actually need to make it so the it’s there in their environment and it’s in abundance, why add extra steps when it’s there available for them? However, when it comes to farmed fish, we’re supplying the diets. So those diets have traditionally been based upon protein sources as fish meal and lipid sources, fish oil, both of those come from the wild captures fisheries, but as we know, the wild captures fisheries are stagnated or in decline. So as aquaculture is increasing, demand increases, but supply has just remained stagnant. So we need to alter these. So we’ve been changing ingredients over the last 20, 30 years and we’ve been changing these using vegetable sources mainly, so soy protein concentrate as the protein source and rapeseed canola as one of the main vegetable oils for fish oil replacement.
Dr. Kristina Jackson:
Yeah. And this is where your work has really been important is tracking this, I think.
Matthew Sprague:
We’ve known, the industry’s known this for a long time coming, and as you know, basically you are what you eat with respect to dietary oils, and that’s reflected in the flesh of the fish. So whatever oil source we put in, it reflects. So what we’ve seen over the last 20 years in sort of farmed salmon is we’ve seen an increase in the use of alternative oils, and these alternative plant-based oils are devoid of any EPA and DHA, they don’t contain them. They have the shorter chain, as you know, the alpha-linolenic acid, but they don’t have any EPA and DHA. So because of that, what we’re seeing is the levels of EPA and DHA in the flesh of the marine farmed salmon decrease.
Dr. Kristina Jackson:
And we’re talking like-
Matthew Sprague:
We now probably have to eat twice as much as what we used to in 2005, for example.
Dr. Kristina Jackson:
Right. So you eat a filet of salmon in 2005, you’re getting about twice as much EPA and DHA in that kind of salmon than you are today because of the fish feed, which really messes up the recommendations and our EPI and all of this gets greatly impacted by that.
Dr. Bill Harris:
It makes a good case for measuring your blood levels.
Matthew Sprague:
Yeah.
Dr. Kristina Jackson:
It does.
Matthew Sprague:
You can’t avoid it because it comes from the wild captures fisheries, as I mentioned, they’re stagnated so there’s not enough of that oil. So we have to replace. And unfortunately we’re trying to meet the global demand for seafood, so increased population, increased demand for seafood so we’re supplying them with this farmed salmon or farmed fish. But unfortunately those farmed fish, because the natural diets are dependent upon the wild captures fisheries, and there’s not enough of it, we have to replace. And sadly that’s what happens is that we see the levels of the EPA and DHA go down. So yeah, we have to eat more.
Dr. Bill Harris:
Are the levels steady in wild caught salmon?
Matthew Sprague:
Yes. So this is one of the issues in terms of, I mean, they’re also in decline. It’s naturally in decline. Fish farms are usually one of the sort of bad guys who are automatically assumed to be causing this, but not necessarily. So I mean, even before farmed salmon started in the 1970s in Scotland and Norway, wild fisheries like the sea trout and wild salmon, sorry, were automatically in decline anyway. Obviously that’s not to say that aquaculture isn’t having an effect, it probably is in some, but there are other issues going on as well.
Matthew Sprague:
But in terms of EPA and DHA levels, they’re probably around about one gram per 100 grams EPA and DHA. Fat content is lower, but we have to remember when it comes to wild fish, particularly the salmon who starts off in the freshwater and then they go to the open marine water where they feed up in the open ocean grounds, which we don’t readily access, they feed up, they produce all that extra reserve of fat content in their flesh, and then they decide to come back home to spawn.
Matthew Sprague:
So during that spawning process, all those lipids, all the fats that they’ve accumulated are then mobilized into gonadal development for reproduction. But also the energy itself is being used for that homeward journey. So when we do catch them, it’s a bit easier as they begin to get towards the rivers and we catch them there, that fat contents come down. So there’s usually an issue that farmed salmon are much more higher in fat than wild salmon, it is true, but it doesn’t necessarily mean that the wild salmon can’t get to those fat levels as well.
Dr. Kristina Jackson:
Yeah, that’s interesting.
Dr. Bill Harris:
Does the feeding of more and more vegetable oil in the farmed salmon change the taste?
Matthew Sprague:
There have been organoleptics may be slight changes in taste. It depends on the inclusion levels of certain ingredients. So producers would always try to mitigate against this, but I think one of the major things is, as I mentioned, salmon have requirements for EPA and DHA in their diet, and it’s normally around about 1% of the diet. Again, it’s like humans, they require EPA and DHA if we want to make them more robust for optimal performance, and particularly in challenging conditions. We find if they have higher levels of EPA and DHA in their diet, they’re able to perform much better than those that have lower levels. It basically just mimics the human story.
Dr. Kristina Jackson:
Things run better? So we have to replace calories, fat, protein, in the diet. Also the algal EPA, DHA that are being grown in tanks even here in the middle of the US, that’s being used in aquaculture to increase levels, is that right?
Matthew Sprague:
Yes.
Dr. Kristina Jackson:
How’s that going?
Matthew Sprague:
So that was predominantly developed for aquaculture because the growth in aquaculture, obviously the investment going in, it’s seen as being profitable. So one of the big stories was this decline in EPA and DHA levels. So a company called Veramaris, which is really from DSM using their algal strains, which most of the algae that went before were just DHA rich only. So there’s a lot of the technology has actually come across from the infant formula. So this is all grown using heterotrophic fermentation units, so big units requires energy sources, carbon sources to feed the algae, and then they produce the EPA and DHA.
Matthew Sprague:
However, it’s all about species strain selection because what you’re looking for at the end of the day is a microalgae that really has these fatty acids. It’s all good and well that they could be 60% of the lipid, but if you only have one gram of lipid, 1% lipid, you’re going to have to produce a lot of that biomass to extract enough EPA and DHA. So you’re looking for a high lipid content, you’re looking for these fatty acids being present and in high numbers. So yeah, this has been developed and it’s actually been used in the aquaculture and the salmon industry at the moment.
Dr. Bill Harris:
Back to the microalgae, do they actually feed salmon the microalgae as a biomass or they extract the lipids and just use the lipids?
Matthew Sprague:
So for this Veramaris one, they actually extract the lipids, yeah. However, the extraction of the lipids is quite a costly procedure and quite intensive so it increases the cost more. You can use the biomass and we have used the biomass in the past. However, in aquaculture, when we’re making feeds, we like either something to be like a protein source, like a meal, or an oil. The biomass is a mix of it. So when it goes into an extruder, there’s a certain amount before it then begins to clog up and cause issues.
Dr. Bill Harris:
Oh, really? Interesting.
Matthew Sprague:
So I think having an oil source is much better, but as we know, when you break open, which is really tough to break open the microalgal cells, they’re obviously more prone to oxidation as well as EPA/DHA. So yeah, it just increases the cost.
Dr. Kristina Jackson:
Yeah, that makes sense. So one of the papers that I always go back to from you is from Scientific Reports in 2016, which is almost 10 years ago now, but it just has all those really practical graphs about how many filets of salmon you’d need to hit the same EPA and DHA. So the name of that for listeners’ purpose is Impact of Sustainable Feeds on Omega-3 Long Chain Fatty Acid Levels in Farmed Atlantic Salmon 2006 to 2015. That also has James Dick on there, who’s the lab lead that we work with. Do you have an update on that paper? What’s been happening since 2015?
Matthew Sprague:
Not really. I’ve been monitoring the levels. There’s been a paper recently from Norway more or less showing the same pattern. So Norway are what we call the global powerhouse production of farmed salmon, they’re 1.3, 1.4 million tons. Scotland is probably about seven times smaller. So there’s data to show that in 1990, for example, the farmed salmon feeds in used in Norway we’re around about 90% marine ingredient inclusion, all right? In 2020 it’s down to about 20% marine ingredient inclusion. So that’s fish oil. And that’s because of the growth of aquaculture, but also the lack of supply of these marine ingredients which we’ve had to replace. So what’s happened is we’ve seen the levels of these EPA and DHA come down.
Dr. Kristina Jackson:
So are they continuing, are they kind of steady from still about half or do you know?
Matthew Sprague:
I would say they’re about steady at the moment. We’ve kind of got that place. And to be honest, if we go any lower, then yeah, there’s going to be impacts on fish health as well because, as I mentioned, requirements of the fish themselves and how much we have to include in the diet. So we can’t really go that much lower.
Matthew Sprague:
But however, you’ve already mentioned the microalgae, there are ever options. So in Scotland, for example, as I mentioned, we’re seven times smaller than Norway and that means we can be a bit more bespoke to how we use marine ingredients because Norway basically just follows that one pattern. Scotland’s following the same pattern in the decline of EPA and DHA, we’re usually a couple of years behind because we’re smaller. But you can get divergence in production strategies. So you can have a farm or a retailer, for example, that wants to produce a salmon which is rich in EPA and DHA and sell it for the healthiness. So they will still include a high fish oil. But you may have others which want to include more plant-based ingredients purely either on cost or sustainability. So it depends on the ethos. It’s not necessarily one is better than the other or one’s worse, it’s just different directions people want to take, within reason of course.
Dr. Bill Harris:
In those products that are richer in omega-3 salmon, enriched at higher omega-3 levels, can they advertise that or put that on the label?
Matthew Sprague:
In the UK I think it’s very low levels that you have to have of either ALA or EPA and DHA just to advertise it being high in omega-3 or a source of omega-3. I mean, the EPA and DHA levels are incredibly small just to even states that it’s a source of EPA. So you can’t get any distinguished nature between walnuts for example, they can still say high in omega-3 and you can have the macro high omega-3, you have to go to the back of the packaging to then look to see what it states in terms of EPA and DHA. And again, some labeling may just say omega-3 but doesn’t state EPA/DHA, some will actually say, “Of which EPA and DHA is X amount.”
Dr. Bill Harris:
Good. Yeah, I mean, I would think you wouldn’t make a product like that if you couldn’t advertise in some way that you’ve got a higher EPA/DHA content.
Matthew Sprague:
That’s the point, exactly.
Dr. Kristina Jackson:
So this kind of leads into the idea of how do people know how much EPA and DHA is in the fish or salmon or any other kind of fish when it’s not required labeling. And also, are we getting to a place where it needs to say a filet of salmon needs to have this amount of EPA and DHA per 100 grams to be considered a salmon? Would that ever be…?
Matthew Sprague:
Well, so as I was mentioning, there’s differences between sort of retailers or producers, should we say, salmon producers and they can specify what EPA DHA levels they want in their product. So even though you’ve got farm salmon, it’s not the same. In one place it can contain, let’s say, 1.8 grams of EPA and DHA per 100 grams. In another farm site or even on the same farm site in a different cage, which goes to a different retailer, it may only contain 0.8 grams based on what’s in the feed. So you really have to check all this different packaging.
Matthew Sprague:
And then as I mentioned, this differences between the portions because very few of us buy whole side of salmon, we often get it into the different sections, different portions. So because the fat content varies from head to tail, if you go for a tail piece, you could be 20, 30% less EPA/DHA than one of the midsections, for example. That’s all down to the fat content.
Dr. Bill Harris:
Really, even on a per 100 grams of fish basis?
Matthew Sprague:
When you normalize, yeah.
Dr. Bill Harris:
There’s just less lipid there in the tail?
Matthew Sprague:
Yeah, so let’s say a standard salmon could be about 12% generally, if you go just behind the dorsal fin, if it’s 12% under the dorsal fin, so the top fin there, that section, if you go behind it, that lipid content can go from 12 to 10% and then if you take the tail portion afterwards, that could be sort of like 6% lipid.
Dr. Bill Harris:
So the percent EPA/DHA is the same across the fish?
Matthew Sprague:
No, the percent EPA/DHA will change. So actually the tail piece has a higher proportion of the lipid as EPA and DHA. Now that’s probably as expected because it contains less of the storage lipid, triacylglycerol, and it contains more phospholipids and obviously you want EPA and DHA in your phospholipids because you don’t want a rigid cell, you want that cell to be more flexible to allow the movement across the cell membranes.
Dr. Bill Harris:
Yes. So what percent of the EPA/DHA in salmon is in triglyceride versus phospholipid? 50/50?
Matthew Sprague:
That’s a good question, man. Probably off the top of my head, I can’t answer that one.
Dr. Bill Harris:
That’s okay.
Matthew Sprague:
The triacylglycerol are normally much more reflective of the dietary oil source. Phospholipids can be, but obviously there are selective fatty acids, so arachidonic acid, omega-6, but also EPA and DHA. But yeah, their exact proportions is something I’m not-
Dr. Bill Harris:
Is there an adipose tissue in salmon that they have fat tissue?
Matthew Sprague:
Yes, yeah.
Dr. Bill Harris:
It’s not stored in the muscle as triglyceride?
Matthew Sprague:
There are all the adipocytes as well, yes.
Dr. Bill Harris:
Okay, okay. Is that right under the skin?
Matthew Sprague:
Well, yeah because obviously you get the white muscle and you get the red muscle as well. So the red muscle is the very small bit of muscle that runs down the flank, and that is your day-to-day energy. The white muscle, which is the main storage, is essentially what is the fight or flight muscle so it’s the anaerobic.
Dr. Bill Harris:
Okay, okay.
Dr. Kristina Jackson:
So when I have a wild sockeye salmon and a farmed Atlantic salmon and I bake them similarly, the wild one always exudes a little white, it’s drier, and then you can see white fat coming out of it. Is that these two different-
Matthew Sprague:
The white is normally the protein.
Dr. Kristina Jackson:
That’s the protein?
Matthew Sprague:
Yeah. So we actually, and I need to publish this piece of work, we took salmon from the same cage, because this is one of the issues, people have looked at the effects of cooking on things like EPA and DHA levels. So we took salmon from the same cage, we took salmon of the same size because size will influence the lipid content. Lipid content is then going to affect the EPA, DHA, etc. So we had fish of harvest size. Harvest size can be anywhere between three to six kilos so I think ours were around about four kilos of fish. We then took off the left flank and the right flank. So left side was going to be analyzed raw as is, the other side was going to be analyzed by a different cooking technique.
Matthew Sprague:
We then actually separated those sides of salmon into separate sections so looking at the different pieces, and again, as I say, subject them to different cooking methods. So we’d done poaching, frying oven, cooking, baking, smoking as well. What we didn’t do was to add any culinary oils because if you add culinary oils, that’s going to affect the fatty acid profile. So we didn’t want to do that.
Matthew Sprague:
Now what you find is when you actually compare these two, if you normalize it so grams per 100 grams, you will find that the cooked has higher lipid content and has higher EPA and DHA content. However, you have to remember you take 140 grams or a 100 grams of salmon, I’ve analyzed that raw, so I should be producing the results as per 100 grams. If I take that same piece, I then cooked it and then analyzed it, there’s going to be weight loss, that cooking loss. So the moisture is one of the main cooking losses. If you actually report the data, 100 grams and a 100 minus x, whatever, the cooking loss, EPA and DHA levels were similar.
Dr. Bill Harris:
Cooking does not destroy EHA?
Matthew Sprague:
No.
Dr. Bill Harris:
Any of those methods anyway?
Matthew Sprague:
Yeah, firstly, all the methods, we tried seven different cooking methods, the only one we couldn’t do was the smoking because smoking you intentionally add the salt for the curation, etc, so that was difficult to do the losses, but it would be more or less the same. Yeah, there was no difference. And where there were differences, again, there were only minor. So cooking doesn’t really have an effect.
Dr. Bill Harris:
Good. Good to know.
Dr. Kristina Jackson:
That’s good, yeah. That is really good. So I think we have hit a lot of this whole process that we wanted to hit. So I guess I have two questions that I’d still like to ask, one is, what should consumers do as far as fish intake goes? I mean, what do you recommend for people to do for fish intake?
Matthew Sprague:
Okay, well, here in the UK, as I mentioned, it’s two portions per week of which one should be oily. So another study that I’ve been looking at recently is looking at basically nutritional composition of the seafood we can buy here in the UK. So this has been going on for a few years now.
Matthew Sprague:
So as I mentioned, the UK with those two portions, they do state that those two portions should provide 0.45 grams of EPA and DHA per day. So this was something that sort of got me thinking a few years back, does it really? Has anyone actually checked it? And I don’t like to go on the daily basis, I always like to present on a weekly basis, and the reason I present EPA and DHA on a weekly basis is because we’re taught to eat portions of fish twice a week and really our only intake is coming from seafood. So that would equate to about 3.15 grams. So that was my benchmark really. And then looking at the 140 grams, as I mentioned, being a portion is what’s recommended in the UK.
Matthew Sprague:
So when you look at, I think it was around about 97 samples, so when I say samples of different seafood types, however within there I also had farmed and wild of some similar species so like the salmon, turbot, sea bass, et cetera. So the only one on average which would give that 3.15 grams is Atlantic mackerel. Everything else you would have to eat at least two portions just to get over that 3.15 grams. So I think when I was looking at the combinations, first of all, I was doing combinations of any two portions. It could be oily, non-oily, two non-oily, et cetera, or even of itself, so mackerel versus mackerel. Out of the number of combinations, I think 90% were below EFSA, so the 1.75 grams of EPA and DHA per week, so a lower recommendation, which is obviously quite shocking.
Matthew Sprague:
When you then took in one portion of oily, which was over 8% fat content with one non-portion, I think it took it up to 70% still being below the 1.75 grams. So when you then change that to two portions of oily and one non-oily, pretty much every single one would meet EFSA requirements. So the 1.75 grams, the lower EFSA requirements, and I think it does go up to probably about 75% actually getting above the UK’s 3.15 grams of EPA and DHA per week.
Dr. Bill Harris:
You need to publish that.
Matthew Sprague:
You would really need to eat two portions of oily and one non-oily.
Dr. Bill Harris:
What are the top five fish consumed in UK?
Matthew Sprague:
UK would be things like it will be mackerel, but cod, farmed salmon, tuna, so haddock. The other thing on tuna as well, tuna is often thought of being as a fatty fish species and it does have high fat content. However, here in the UK, what we can buy in the retailers is really just the loin pieces so the short or the back pieces, and you’ll actually find that that contains less than 1% fat. So I mean, tuna contains high amount of DHA, but because it’s got the low fat content, all the fatty sections obviously they go off to places like Japan where they’re highly prized for the sashimi sushi markets.
Dr. Bill Harris:
So albacore tuna higher than chunk light? Not much?
Matthew Sprague:
Albacore and Yellowfin are the two species we mainly buy in the UK, and as I said, both of them are exactly the same. You probably have to be somewhere around about 20 portions a week to get the levels. Cod, for example, cod would be 11 portions per week. Tilapia, which is freshwater is probably around about 60 or 70 portions. It’s a freshwater species. But it’s not as bad as the Pangasius, the river cobbler, you would have to eat I think it’s around about 200 odd portions just to get 3.15. But we have to remember where they’re grown, these aren’t oily species for a start. And where they’re grown, they’re grown as protein sources, so it’s how you look at it.
Dr. Bill Harris:
So typically freshwater fish generally are going to be very low in omega?
Matthew Sprague:
Yeah. I mean, as we mentioned, they do have the machinery to make EPA and DHA, it’s just that they can’t make it in high amounts. Whereas the marine species, particularly the high trophic ones, they can’t make it whatsoever.
Dr. Bill Harris:
And there aren’t any microalgae in freshwater to produce omega-3?
Matthew Sprague:
There will be phytoplankton, the microalgae, but again still it’s not in the large amounts that you find in the marine environment.
Dr. Bill Harris:
Okay, good to know.
Matthew Sprague:
Again, it’s all about the species and the types of the strain and the species and lipid contents, et cetera.
Dr. Kristina Jackson:
It really is, and probably two to three servings of fish a week is the old one to two servings.
Dr. Bill Harris:
I’m kind of surprised that Norway, I mean, Canada I would think would be a big producer of farmed salmon. Not true?
Matthew Sprague:
Yeah. Yeah. So Canada, but mainly Chile. Norway and Chile, yeah, these two are probably the bigger nations. And then you’ve got Canada, Scotland, the Faroe Islands, but also down in Australia, Tasmania, in England as well.
Dr. Bill Harris:
But still like 70% of the whole market is Norway?
Matthew Sprague:
Vast amounts, yes. It’s the same with in Scotland for example, we’ve got the Label Rouge fish, which is seen as better, premium status, which often gives it the higher priced premium value. But in terms of production, Norway, well ahead in terms of the volumes.
Dr. Bill Harris:
Good for them.
Dr. Kristina Jackson:
Well, we usually started off by asking how you got into this field in the first place. And I am curious, how did you land getting so deep into the fish world? I mean, you’re in Scotland, so that probably had a lot to do with it, but can you give us a little background?
Matthew Sprague:
Yeah, my background is actually biology, so I was always interested in science, and I think I was always interested in research, so mainly biology and chemistry, those are the two subjects I really enjoyed at school. So when I went off to university, I was just stuck in the sort of biological science degree. And then in my final year when I was doing a project, it was on fish nutrition and it was actually my supervisor down there, Matt had done his PhD in Stirling. So that’s how I got to know about Stirling. So when a PhD position came available, I applied for it and I was fortunate enough to get it, however I was actually working more on feed intake physiology. So there was Gordon Bell in the nutrition group, and he was part of my supervisory team. So when I finished my PhD, I was fortunate to move down into the nutrition group, and I think that’s probably where all the money is, to be honest.
Dr. Kristina Jackson:
Yeah, it helps.
Matthew Sprague:
So when I started working in the nutrition group, it was working on sustainable feeds, but I was also looking at things like the lipothinic contaminants, the PCBs, dioxins and those things.
Dr. Bill Harris:
Let’s talk about that. That was 10 years ago, at least 10 years ago, when that big scare about all the PCBs and dioxins in farmed salmon.
Matthew Sprague:
I think that was about 20 years ago in 2004, to be honest.
Dr. Bill Harris:
Was it that long ago? Is it all cleaned up or what’s the status?
Matthew Sprague:
Yeah, so I mean with that paper, it’s one of these things, it’s the usual thing where the media jump all over it and it’s the sensationalist headlines. So that’s not what the authors were looking at. The authors were showing that at that time the levels of dioxins and PCBs were much higher in farmed salmon compared to wild salmon, even though they were within the permittable legal limits. And as I mentioned, media jumped on top of that.
Matthew Sprague:
So yeah, the industry took a bit of a knockback from that, but as the public doesn’t always see the amount of research that goes into behind the scenes work on trying to solve many of the issues, we have to remember aquaculture or aquaculture as it is now, so from its intensive aquaculture where we think of the cage farms, et cetera, is still in its infancy. It’s from the 1970s. However, aquaculture per se, we can date back over 4,000 years. And it was mainly those lower trophic species. It’s because of the development of nutritional feeds, tailoring those to get the optimal performance for the fish that the intensive farmed high value species, such as salmon, have been able to be achieved since the 1970s.
Matthew Sprague:
So yeah, the industry was actually looking into trying to reduce the levels. I mean, 20, 30 years ago, the industry would’ve known about the levels of fish oil, there’s not enough of those for a start. So replacing fish oil with plant-based oils can reduce the levels of these dioxins. PCBs because they’re not really present in the plant-based ones. There are ever contaminants that when we have to do this, we have to think about new contaminants. But concentrating on the PCBs and dioxins, this was all coming from ourselves, humans.
Dr. Kristina Jackson:
We’re doing it to ourselves.
Matthew Sprague:
Industrial processes, mainly as a byproduct. They can be produced naturally as well from forest fires and volcanic eruptions. But the main production of these into the environment and particularly into the marine environment was coming from industrial production, which was always in the Northern Hemisphere, okay? Makes sense over time. So these found a way, they’re very lipophilic so they love fat, so they make their way into marine environment go into the sediment, and when the sediment’s disturbed, they go into the organisms, marine organisms, and find their way into the fat content. So when we then harvest those fish and we make them into fish meal and fish oil, obviously the contaminants are going to be quite much higher in that fish oil. So it is not the fish’s fault, it’s our fault. So we’re to blame.
Matthew Sprague:
So that was an issue for many years, but however, there became techniques where we can actually decontaminate the levels of these contaminants so we can actually reduce the levels. And that’s still being used today just to remove dioxins and PCBs from the fish oils, which are then used in fish feeds, which can then lower the levels that you find in farmed fish. So what you find nowadays, and part of that also is because of the change from fish oil to plant-based oils is actually farmed fish contain lower contaminants than the wild counterparts.
Dr. Bill Harris:
Interesting, let’s talk about mercury too, because it always comes up. Mercury in salmon, as I understand it, is not a problem?
Matthew Sprague:
It’s not really a problem, no. Normally we talk about it, it’s one of the issues with regards to seafood intake. It’s confusing out there in terms of what is being recommended. We’re taught to eat two portions of fish per week of which one is oily, but if you are pregnant or if you are of childbearing age, so females obviously, they’re taught to limit certain species due to mercury. It’s not really mercury, it’s the methylmercury, which is more neurotoxic.
Matthew Sprague:
What you find is around about 80%, particularly in higher trophic species, of the total mercury is methylmercury. Lower species, it’s probably around about 50%. However, I know you’ve had Tom Brenner and other people on in the past as well, and they’ve been showing, and I’ve actually been reading one of their papers recently, it’s showing that actually with the cognitive function, DPA and DHA benefits outweigh that from the risk from the mercury. However, from our perspective at the moment, we still have to say go with what the recommendations say, but we are trying to change that by producing the evidence to say, “This is why you need to change recommendations.”
Dr. Bill Harris:
Right. We agree, right?
Dr. Kristina Jackson:
Yeah, yeah. It’s tricky though. It’s not a fun thing to have to decide and stress about. Yeah, so, I mean, that’s part of the reason for us the testing helps clear up that conversation a little bit, and if you want to just use supplements at that point for pregnancy, do not have to stress about it as much, that’s also been shown to be really good. But fish also, like you said, have so many nutrients that are really important for pregnancy.
Matthew Sprague:
Yeah, iodine is another important mineral. So certainly it’s females who usually deficient. It’s important throughout the whole life stage, not only just for the unborn fetus, but for adults as well. And in the UK we don’t have iodized salt. But if you’re eating haddock, if you had a portion of haddock and a portion of mackerel, you’d probably get two-thirds of your iodine intake. So there’s a paper I published looking at the seafood species, but instead of EPA and DHA, the iodine managed to get that one out first. So I think the rest of the third mainly comes from milk, milk intake. Obviously if you’re eating plant-based ingredients, again, you’re going to get that iodine deficiency.
Dr. Kristina Jackson:
Yeah, big problem.
Matthew Sprague:
Going back to when you were saying selenium as well, so the selenium issue as well, that’s another big issue with regards to the replacement of plant fish meal with plant-based meals. So the plant-based meals, depending where they’re grown, it all depends on selenium in the environment. But what we’ve been seeing is that the selenium levels have been coming much lower as we’ve been increasing the plant-based proteins in there. So there’s issues in there which we’re trying to resolve as well.
Dr. Bill Harris:
Interesting, great.
Dr. Kristina Jackson:
Yeah, this kind of came out of, so your background getting into this area, and it sounds like you ended up at Stirling and really found your niche and have been in this area since your postdoc or since your graduate work?
Matthew Sprague:
Yeah, so my PhD was 2002 to 2006, and then I moved down to the nutrition group as I was saying. So that was on the work that they were doing, which they’d been doing. So it started off people like Douglas Tucker, Gordon Bell, James Dick, as you mentioned, John Sargent, big in lipids. So they were working on sustainable aqua feeds and been doing that for many years. So I became part of that group, started working on different aspects,
Matthew Sprague:
And then it kind of developed that, it’s looking at the impact of these sustainable feeds, but from the human perspective. So I kind of transect that at the final level of how much is in the flesh of the fish and how much is being delivered to the humans. So as I mentioned, that got me quite curious in terms of current seafood recommendations and particularly when they state how much EPA and DHA we should be consuming and are fish actually containing that much?
Matthew Sprague:
Another part that I’ve been working on as well is the GM issue as well. So we’ve been for the last 10, if not longer years, been looking at working with a group from Rothamsted Research, so big agricultural research institution. And what they’ve been doing is to make EPA and DHA into an oil seed. So there’s camelina, flax, it’s also being done elsewhere using canola, but that’s mainly DHA rich and that is actually being used or allowed for use in salmon. The camelina one, I believe, is going through commercialization as well, so this one contains both EPA and DHA and we’ve been testing it in different species from bluefin tuna, sea bass, obviously salmon, sea bream, and I believe it’s also been tested in humans as well with Phil Calder’s group.
Dr. Bill Harris:
So this genetically modified oil is going to make its way into human food without getting, I guess, demonized like so many GM products.
Matthew Sprague:
Yeah.
Dr. Bill Harris:
Good, great. Finally, rationality is going to take over.
Matthew Sprague:
I think it’s all about anything GM, it’s all about education. It’s about explaining to the normal population why you’re doing the work. So in the context is EPA/DHA as we know are very important for human health, but it’s also important for fish health as well. Levels in seafood are coming down, there’s not enough of it, we need to produce more. We can’t go anywhere else really, the only other options are to carry on harvesting down the trophic levels like krill, but these are in niche markets because they can then affect the higher trophic species. So it’s either microalgae, as we’ve mentioned, or GM issues. So over here in Europe, we’re probably a bit more tight on the GM issue, whereas in Chile for example it’s much quicker to get it through the regulation processes. So that’s probably going to where it’s going to be the main aim and use will be first before it reaches elsewhere.
Dr. Bill Harris:
That’s good news, good news.
Matthew Sprague:
That then brings us onto that final thing is what we are trying to do with the farmed salmon? Are we looking to maintain the current levels or are we looking to increase them back to five years ago or even 10 years ago? Yeah, at present I can tell you that farmed salmon contain exactly the same amount of EPA and DHA as wild Atlantic salmon.
Dr. Bill Harris:
Good, good to know. Good thing to end on.
Dr. Kristina Jackson:
Yeah, this was really fascinating. Thank you so much for joining and sharing all this I think super useful information and it’s been great. Thank you so much. Keep up the good work.
Dr. Bill Harris:
All right.
Dr. Kristina Jackson:
All right.
Dr. Bill Harris:
Take care, Matthew.
Dr. Kristina Jackson:
Thank you.
Matthew Sprague:
Okay, thank you.