Imagine eating fish, every day, for a year. What would that mean for your health?

It’s a question that journalist Paul Greenberg set out to investigate in the new FRONTLINE documentary, The Fish on My Plate. 

Greenberg, the best-selling author of American Catch and Four Fish, says this unique one-man study was motivated by a desire to understand which fish are “good for me and good for the planet.”

A lifelong fisherman, Greenberg began casting lines with his father when he was just five years old. From a young age, he says, he began to understand that overfishing carried far-reaching environmental implications.

Today, more than four decades later, global fish consumption is at an all-time high, with growing demand increasingly depleting natural fisheries. As Greenberg notes, “We’re producing about 80 to 90 million metric tons of wild seafood every year from the ocean … that is equivalent to the human weight of China.” Fish farming — or aquaculture — is helping to fill the void, yet critics say the practice creates more problems than it solves.

Ahead of the April 24 premiere of The Fish on My Plate, we spoke with Greenberg about lessons learned from his year of eating fish, why he says “we’re going to have to change the kinds of seafood that we eat,” and why he calls the omega-3s found in fish oil the “Forrest Gump” of molecules. Here’s what he had to say.

Note: This interview has been edited for clarity and length.

One whole year of eating seafood for breakfast, lunch and dinner. That’s a lot of fish. What motivated you to take this experiment on? 

I’ve been writing about fish and seafood for over 10 years now, and you can’t get away from the fact that fish is always held up as “the healthy food.” I also heard epidemiological evidence [showing that] fish eating societies seem to have lower rates of the so-called Western diseases — lower rates of heart disease, there’s some evidence of higher cognition among certain populations, better test scores, that sort of thing. So I just thought, what if I were to really take on the diet of somebody — almost like a Pacific islander — and really make fish the central part of my diet? I wanted to see if I would register some sort of effect, either in my cardiac health or in my mental health.

I’m sure you must get asked you all the time, “What type of fish should I be eating?” If there’s one thing I learned from The Fish on My Plate, that’s not so simple to answer. But are there some general things you suggest people consider when they’re ordering seafood at a restaurant or buying at the supermarket? 

I think first of all, the number-one question is: Where did the fish come from? And does the person who is selling your fish have a good handle on that? I on occasion torture waiters and ask them to identify where their fish is from, and if they have to go back to the kitchen more than once, then I know that there’s a serious amount of confusion. So traceability is really important. Greenpeace actually puts out an annual report called CATO. It stands for “Carting Away the Oceans,” and whatever you may think of Greenpeace, at least they took some time to evaluate supermarkets on their buying and purchasing policies. In that report, paramount to really determining what was or was not sustainable, was whether or not a supermarket had a traceability program in place.

Beyond that, there’s certain go-to fish that I usually go to because I know that they are high in omega-3s and they fall within my budget. Quite often, I will buy Alaskan wild sockeye salmon. People always say, “Oh salmon, it’s so expensive.” The place where you get into trouble with wild salmon is when you start going to the fresh fish counter, where you’ll start seeing $15, $20, $25 a pound. But in fact, outside of wild salmon season from June to August, fish you’re going to see on the counter has usually been defrosted. It makes much more sense to go to the frozen food bin and get those nice vacuumed-packed Alaska sockeye salmon that usually come in around $10 a pound. It’s boneless, it’s portioned out, and because it’s been frozen the moment the fish comes out of the water, you can bet that it’s going to have a higher quality than the fish that’s been defrosted and is laying out at the fresh seafood counter.

In terms of the health benefits of a diet rich in omega-3s, what do we know about where the science is? You’re working on a new book about this, The Omega Principle. What have you learned so far? 

What I’ve found is that the randomized control trials, which are the gold standard in medical research, those kind of gold-standard trials have often found inconclusive results.

On the other hand, observational studies, which tend to include many more subjects over much longer periods of time, do show more significant effects. For example, there was a study published in the journal Nature, I think it was in 2016, that showed a 6 percent reduction in risk of cardiac death. Now, it’s a little bit comparing apples and oranges with randomized control trials and observational studies, but I do think that the omega-3 people do at least have a leg to stand on in saying that there is evidence outside of randomized control trials that seems to suggest an association with cardiac benefit.

Then there’s the whole issue of mental health. This is still an emerging field. The human brain is 25 percent DHA omega-3 fatty acid. It’s part of the brain. So, the real question becomes, if it’s part of us, if we have more of it, [is that] better? And I think that’s where people are struggling to show effect.

The thing I’ve decided is that omega-3 is the “Forrest Gump” molecule, in that it shows up at key moments in epidemiological history and evolutionary history. You’re not quite sure what it’s doing there, but it’s there. So, I’m trying to write this book from that perspective.

Your research took you all around the world, from Peru, to Norway, to Alaska and even the waters of the Long Island Sound where you first learned to fish. What did you learn about our overfishing problem, and what does the future look like for aquaculture, which is controversial in its own right. 

We have reached a point where we have topped out what the ocean can produce, at least in its present compromised state. Right now, we’re producing about 80 to 90 million metric tons of wild seafood every year from the ocean, and that is equivalent to the human weight of China taken out of the ocean each and every year.

The estimates are that if we were to rebuild every overfished fish stock out there, we might get another 10 to 15 million metric tons. When you look at the graph of protein consumption in the world, you can see that that’s not going to cut it, especially if fish is going to be a major part of our diets. [It’s] just plain and simple math — you have to have aquaculture.

I do think aquaculture should exist, but I think in the early days of aquaculture we had a model that I would call “delete and replace.” If you look at salmon, for example, in the Atlantic, we lost huge amounts of Atlantic salmon populations by damming the rivers where they spawned, but also overfishing them. And then no sooner did those numbers decline that they were replaced by farmed salmon in the same bays and fjords where wild salmon would have migrated to.

So, we don’t want any more delete and replace. We need to figure out a way to have aquaculture be a net source of marine protein, and we’re on the edge right now. In the film, we go to Peru, we look at the Peruvian anchoveta as the largest fishery in the world, but 99 percent of it is used as animal feed. So, to me, that’s a little bit of an outdated model. And since there are increasing models for making feed that doesn’t involve the use of wild fish, I think that we’re on the verge of having a truly net-gaining form of aquaculture available to us.

When you speak to policy experts, what are the solutions they point to for reversing — or at least minimizing — the damage from overfishing in the meantime?  

The solution that has worked in many cases is limited entry fisheries. In other words, you try to define how many catchable tons of fish there are out there in a given species with a given stock in a given area. And then, in advance of the fishing season, to divide up that “surplus” — the fish you can harvest and still expect to have the same amount of fish the following year — amongst a pre-recognized number of fishermen, and then fishermen must stop fishing when they’ve caught their individual quota. I should note, this is an extremely controversial thing within fishing communities.

In other fisheries, they have what’s called “observer coverage” — people actually on the vessels who are not fishermen, who are recording the catch and where there’s just a general culture of compliance. That’s another thing which is hard to achieve. Healthy abundant fisheries tend to breed cultures of compliance, whereas overfished, mistreated fisheries, everyone’s trying to eke out their share and are more prone to bad behavior.

The Maine lobster fishery is an example of an excellent fishery. It’s doing very well, it’s very productive. In the Maine fishery, spawning females must always be returned to the water if they end up in your trap. Lobsters above a certain size, females above a certain size, must always be returned. So, if you could do that with fin fish, you could probably solve the overfishing problem, because you’d always be putting back the big females.

There’s a tongue-in-cheek fisheries term, “a BOFFF,” which stands for big old fat female fish. The gold standard for fisheries is to keep the BOFFF in the water. Big old fat female fish have been shown to have more eggs and higher quality eggs, and if you can preserve the spawning females, you can actually do a lot to protect the fishery. But it’s hard to do that if you’re dragging a trawl net through Georges Bank. I mean, how do you pick out the big old fat female fish and put them aside? There are some places on the West Coast where they’re doing trap fisheries, where you literally trap things like sable fish. You could release the big fat female fish in a fishery like that, but that’s a whole other set of gear. Fisherman have already invested so much in their gear that to change it is probably difficulty.

Aside from some of these policy considerations, are there broader questions we should be asking as a society about our relationship to the ocean and whether we can catch seafood in a more responsible way? 

Yes, but I actually think the answer lies beyond the question of seafood only. We tend to look at the seafood system as a discrete system that’s somehow separate from the larger food system. But I would argue that if you look at all of our food systems, aquaculture is much more carbon efficient, water efficient, fuel efficient, than almost any land animal agriculture or animal husbandry. So, right there, if we were to step back and say “Huh, let’s not just try to get our fishing under control and our aquaculture under control, let’s try to get our land food production under control.” Because in the end, if you’re producing a lot of cows and pigs and chickens, that requires a lot of corn, which in turn requires a lot of nitrogen fertilizer, which goes into our water ways, which in turn degrades our fisheries.

As far as getting more seafood onto our plate and to make it more a part of our diet, we’re going to have to change the kinds of seafood that we eat on a regular basis. The absolute no-brainer when it comes to seafood is bivalves — clams, mussels, oysters, as well as sea vegetables such as kelp and so forth. Those creatures require no inputs in terms of fertilizer. They actually clean the water while they grow and they’re very low carbon to harvest — particularly mussels — but not everyone loves them. Something’s got to give.

The other thing is that we need to figure out a national aquaculture policy for the country. We are right now 15^th in terms of total tons of aquaculture produced. Meanwhile, we have the second largest seafood footprint in the world. So, we’re not doing our share. A lot of that is that we just don’t seem to be able to resolve our NIMBY issues. Nobody wants to have a mussel farm or a fish farm in their view shed. So, we need to figure that out and we need to figure it out in a way that’s fair to fish consumers but also fair to landowners.

How often are you eating seafood now?

I definitely backed off. I actually liked having seafood in my diet, and I have to say, I felt better eating fish. There’s this funny little quirk of when you decide to eat fish all the time, particularly when you go out to dinner, when you order the fish on the menu, the fish always comes with healthier stuff. Like if you order steak, it comes with French fries, but if you order salmon, it comes with broccoli.

I haven’t been eating as much fish now. I did end up with pretty high mercury levels and that did spook me. There’s a little bit of mercury in most seafood, and if you’re eating it as often as I was eating it, it’s going to add up. I didn’t notice any symptoms, but it spooked me. I’m kind of in a reset mode right now, where I’d like to have seafood be a major part of my diet for all the reasons I said — I think it’s an environmentally sound way of getting protein if you do it in the right way — but I would like to figure out what’s the upper level that I can push, and with which seafood, so that I can achieve a mercury level that is acceptable to me.

What surprised you the most in making this film?

My attitudinal change about seafood. Previously, you go into the super market and you’re like, “Huh what’s for dinner tonight? Is it going to be the red steak or the white chicken?” But when you cut all of that away, when the meat department is no longer a purview, you go to the seafood counter or to the frozen section, and you realize there’s actually quite a large selection and that you can have variety in your life. If you don’t just think about it as fish, but as, “Oh, I could have mussels, I could have salmon, I could have tilapia, I could have haddock,” those flavors tend to annunciate themselves once you’ve fine-tuned yourself. When you really engage in a big way, you develop a better appreciation of the subtleties of seafood.

---