The algae trout


By Safina Center Fellow and Writer in Residence Paul Greenberg

Anyone who keeps tabs on health trends is aware that in the last few years considerable doubt has been cast as to whether omega-3 fatty acid supplements provide the health benefits their manufacturers claim. Of particular note were several “meta analyses,” studies of studies, that sought to pool the results of multiple lines of research and determine whether or not omega-3s had an effect of significance on cardio vascular health. In the course of my omega-3 book research I have read meta-analyses that have shown significance and others that have shown none. It’s confusing.

But there is one area where the significance of omega-3s is undeniably significant: that is in the feeding of aquacultured fish. Plain and simply oily fish like trout and salmon need EPA and/or DHA omega-3 fatty acids in their diet to grow normally. And here’s the rub: the natural supply of EPA and DHA is limited. EPA and DHA are mostly synthesized from oily fish like Peruvian anchoveta and menhaden. This has in turn created a bottle neck and a dilemma for aquaculture. Fish farming may be the fastest growing food system on the planet but without more DHA and EPA, that growth will grind to a halt.

Enter the algae trout.

Last fall, on the advice of a former USDA aquaculture scientist named Rick Barrows, I made my way up through the parched country of the blazing two-year California drought, through a haze of smoke of a wildfire burning just on the border with Nevada to pay that trout a visit. Down a gravel road I found David McFarland noodling around his trout raceway, getting ready to close up shop for the evening. “So you probably want dinner right? Over in Susanville there’s Mexican, Chinese, what’s your pleasure?”


“What about a trout?” I said. “Yeah, we can do that.” He put his dip net into the raceway and pulled out a rainbow of about 3 pounds, every bit as vibrantly colored as a wild trout.

When he filleted the fish it was very close in flesh quality and color to Atlantic salmon and their EPA and DHA levels equal or exceed wild fish. The fish are a cross between steelhead trout, a sea-run fish close in genetics to a Pacific salmon, and a famous strain from Eagle Lake across the state border. The Eagle Lake fish are known for their deep red color. This characteristic is accentuated by the natural astaxanthin which occurs in the pigmentation of the algae.

The fact that the MacFarland trout are raised entirely out-of-ocean means a good deal of biosecurity for the ocean at large. No sea lice, no infectious salmon anemia transfer to wild stocks. Moreover Barrows and McFarland have found that eliminating fish meal from aquaculture feed can have added health benefits for the fish. “With fish meal, that stuff is loaded with calcium and phosphorous, “Barrows told me. “That will eventually cause the fish to be unable to uptake the trace amounts of copper that they need. Their color will fade, their fins will erode. That’s why farmed fish can look so nasty.” It seems then that we are just around the corner from a perfect omega-3 protein. So why aren’t we all eating it?


“The problem is it’s expensive,” Barrows explained. “If you look at pricing it’s the oil cost that’s killing us.” For up until now, nobody has figured out how to grow algae in a way that actually makes efficient use of the photosynthesis that is natural to it. Remember, algae originated most likely from a collaboration between two organisms. One organism was a simple respiratory cell that, like any non-plant cell burned sugars for energy or transformed them into oil for later use. The other, the chloroplast, was a photosynthetic creature that created sugar out of carbon dioxide and sun.

For many start-up algae companies, the surest pathway to creating a lot of algal oil has been promoting the algae’s respiratory side. As the director of one of the largest producers of algal oil put it to me, “algae are not that efficient at transforming sun and carbon into sugar. But they are extremely efficient in turning sugar into oil.” As a result most algae grown for oil has to be amped up from the distillation of sugars and the promoting of respiration.

But by pursuing this super-charged algae path once again you have a wasted industrial process. The growing of sugar cane to feed algae so that it will churn out omega-3s. And the cost is considerable. A trout or salmon fed with this feed is double the cost of a typical farmed fish. The proponents of sugar-fed algae argue that this is merely a question of scale, and indeed the largest producers have created giant distilleries in Brazil that may indeed make algal oil competitive with anchoveta.

But all this is still a work-in-progress. A work that was complicated this summer when the The Association of American Feed Control Officials ruled that oil derived from algae would not qualify as a fat suitable for aquaculture feed. The fact that algal oil can already be put in baby formula, salad dressing and a host of other direct for human consumption products makes no difference.

And so the algae trout while delicious and sustainable is not an easy fish to find….

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Paul Greenberg is author of a forthcoming book on omega-3 fatty acids and the marine food web, titled The Omega Principle: A Journey to the Bottom of the Marine Food Web. It is due out by Summer 2018. The accompanying Frontline documentary is slated for release in early 2017.

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