In “The Fish on My Plate,” author and fisherman Paul Greenberg sets out to answer the question “what fish should I eat that’s good for me and good for the planet?” As part of his quest to investigate the health of the ocean — and his own — Greenberg spent a year eating seafood at breakfast, lunch and dinner.
Courtesy of FRONTLINE
Facts about the virtues of eating fish can be slippery. On the one hand, fish provide protein and omega-3 fatty acids, the substance in fish oil supplements, which is thought to boost cognitive health. Plus, unlike cows, fish don’t belch vast amounts of the greenhouse gas methane into the air. So, fish should be good for your health and the environment. But the science of omega-3 benefits is far from settled, and as fish farming grows to keep up with global demand, the industry is raising new questions about environmental sustainability.
New York Times bestselling author and avid fisherman Paul Greenberg wanted to learn more about how eating fish can change human health and the world’s marine environments. He ate fish every day for a year to see how it would affect his health and traveled around the world to learn more about the challenges of fish farming. His experience is captured in a FRONTLINE documentary called The Fish on My Plate airing Tuesday. (You can also watch it online.)
We watched the film and talked with Greenberg about what he learned while making this documentary. The conversation is edited for clarity and concision.
As a fisherman who enjoys catching food from the wild, do you think we need fish farming?
If everyone’s going to be a vegan, no, we don’t need fish farming. If we want to have animal protein in our lives, then yes, I think we do need it. People often compare wild fish to farmed fish, but what we should really be doing is comparing fish to other forms of protein. Because things like beef really are a tremendous burden on the planet in terms of resources, we’re never going to get to the place where everybody on the planet can eat beef. But I do think we’ll get to a place where everybody can eat mussels.
Only eating wild fish doesn’t work with the equation right now. We’re catching 80-90 million metric tons of wild fish per year, and that’s not going to meet the protein needs of the world, plus it’s putting a lot of pressure on fish populations. I’d rather see that need met through aquaculture [fish farming] than through more beef, pigs or chickens.
What makes a fish a good candidate for aquaculture?
Some criteria are a general adaptability to confinement, a resistance to disease, the ability to produce a lot of offspring, and fast growth. And you see fish with these traits rising to the top of fish farming. Take tilapia. It grows very fast, from an egg to an adult in nine months, whereas a salmon can take 2-3 years.
That said, people like some fish more than others. So there are efforts in aquaculture to tame certain fish [like salmon] because there’s a market for it, not because they’re the best suited for farming.
The film shows that fish farming is far from perfect. What are the biggest challenges facing fish farming?
It’s what the farmed fish eat and where they live.
We tend to prefer carnivorous fish like salmon, and they like to eat other fish. So roughly 20 million metric tons per year — a quarter to a fifth of the global catch — goes into catching fish like anchovies that are ground up and fed to other fish. Salmon farming has become more efficient over the years through selective breeding and improved farming techniques. It used to take six pounds of wild fish to produce one pound of farmed salmon; now it takes less than two pounds of wild fish. But at the same time, the amount of farmed salmon that we’re growing is increasing, so the pressure on these small wild fish continues.
This problem is being worked out in techniques using other food sources, like fishery byproducts that would have been thrown out anyway, algae, or soldier flies, for example, to make fish feed.
What’s the problem with where fish farms are located?
This is a thornier issue. Any time you aggregate large amounts of livestock in an area, you’re going to attract disease. In the case of salmon, the most famous disease is a parasite called a sea louse. When wild salmon swim past farms, the sea lice can infect them. If a juvenile salmon gets more than 10 sea lice, it will die.
The other issue is that if you have a lot of animals poop in one place, you can have nitrate overload, and cause algal blooms in the marine environment. So there are lots of people who would like to see fish farms taken out of the ocean entirely and moved to a tank.