From nutrition to sustainability to cost to contaminants, there's a lot to consider when weighing the pros and cons of farm-raised vs. wild-caught fish. Nutrition Diva sorts through the confusion.
Just about everyone I know is trying to eat more fish these days. Eating at least two servings of fish or shellfish per week appears to reduce the risk of heart disease, delay the onset of Alzheimer's and dementia, and (if you're pregnant) make your baby smarter and healthier.
When you get to the fish counter, however, you've got some decisions to make. In particular: should you buy wild-caught or farm-raised fish? Many assume that wild-caught fish must be a lot better for you because it's more "natural." But it this necessarily the case? And what about environmental issues, food safety, sustainability, and cost? With this many factors to consider, it's impossible to make a blanket recommendation. Choosing between wild-caught and farm-raised fish depends on what kind of fish you're buying, as well as where and how it is fished (or farmed).
Is Wild-Caught Fish More Nutritious?
Today's farmed Atlantic salmon provide significantly more omega-3 fats than wild-caught.
The nutritional differences between wild and farmed fish are not as great as you might imagine. Farmed and wild-caught rainbow trout, for example, are almost identical in terms of calories, protein, and most nutrients. There are some minor differences: Wild-caught trout have more calcium and iron. Farmed-raised trout have more vitamin A and selenium. But for the most part, they are nutritionally equivalent.
One of the main reasons we eat fish, of course, is that they are a uniquely potent source for long-chain omega-3 fatty acids. And here, farmed fish often have the advantage. Today's farmed Atlantic salmon provide significantly more omega-3 fats than wild-caught Atlantic salmon, for example.
The color of the flesh is not a reliable guide to omega-3 content, by the way. Atlantic salmon (whether fished or farmed) is a pale orange, while Sockeye is dark red. The paler Atlantic salmon provide more omega-3.
Are Farm-Raised Fish Higher in Contaminants?
In 2004, a widely-cited study found the levels of PCBs, a potentially carcinogenic chemical, to be ten times higher in farmed fish than in wild-caught fish. That sounds pretty scary, but the amount of PCBs in the farmed fish was still less than 2% of the amount that would be considered dangerous. The differences may also have been exaggerated. Subsequent studies found PCB levels in farmed fish to be similar to those of wild fish.
The other contaminant that most people worry about with fish is mercury. The fish that present the biggest concern (swordfish, king mackerel. tilefish, shark, and tuna) are all wild-caught. The most common farm-raised fish (catfish, tilapia, and salmon) all have low or very low mercury levels.
U.S. regulations prohibit the use of hormones or antiobiotics to promote growth in farmed fish.
What about antibiotics or hormones? Are fish farmers dumping drugs and other chemicals into the ponds to maximize harvests? According to Linda O'Dierno, who is an Outreach Specialist for the National Aquaculture Association, U.S. regulations prohibit the use of hormones or antibiotics to promote growth in farmed fish. This is not necessarily the case in other countries.
Are Farm-Raised Fish Genetically Modified?
It is also widely-believed that farm-raised fish are genetically modified--yet this is not the case. You may have read, for example, about striped bass that have a zig-zag in their stripes. These fish do exist but they are not genetically modified. They are simply a cross between striped bass and white bass--done the old-fashioned way.
There are currently no genetically modified fish for sale in the U.S. At least, not as food. You can buy genetically modified fish for your tropical fish tank that glow in the dark, thanks to some genes borrowed from iridescent coral.