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Seaweed Aquaculture: A False Promise

A response to “Blue Revolution”

Michael Holtz’s story on new technologies for expansion of seaweed cultivation in Indonesia (“Blue Revolution,” in the current issue of EIJ) answers none of the questions that any environmentalist worth her salt would ask about such project. Holtz relies entirely on the testimony of the seaweed entrepreneurs. He would have done well to interview a few conservation biologists or marine ecologists, people who might have anticipated the concerns of the readership of an environmental journal.

Holtz describes seaweed farming as “ecologically friendly” and “ecologically sustainable,” and then makes a favorable comparison with salmon and shrimp farming. That is an awfully low bar. What anyone familiar with the disastrous history of modern aquaculture in Southeast Asia will want to know is: What is growing in these Indonesian shallows now? What will be displaced?

Indonesia is close to the center of diversity and dispersal for the fauna of the Indo-Pacific coral reef. After tropical lowland rainforest, this is the richest, most diverse ecosystem on earth. These Indonesian shallows that are to be planted with seaweed, are they now fringing reef?

Southeast Asian aquaculture – shrimp, milkfish, carp, perch, oysters, mussels – has often been accomplished by clearing of mangroves, which we know now is a vital nursery for reef fish and oceanic fish and a crucial buffer against storms. What is currently growing in the shallows to be planted to seaweed? Hopefully not mangroves. Maybe eelgrass or turtle grass? Another indispensable nursery. From the story’s opening illustration I would guess some kind of seagrass. It looks like that kind of habitat.

This is particularly important question in evaluating the seaweed option, in that Holtz frames seaweed as one answer to the worldwide decline of fisheries. He correctly names overfishing and climate change as causes of the decline. But in the area he calls the “Coral Triangle” another huge factor has been the destruction of mangrove and seagrass nurseries for aquaculture and for other coastal construction. Will the proposed seaweed boom simply be robbing Peter to pay Paul? Will it be (to use a grim metaphor from the US misadventure in Vietnam) destroying the village in order to save it?

Holtz notes that the biggest market for seaweed and its carrageenan is in processed foods. He fails to acknowledge the long campaign by foodie environmentalists, locavores, environmental-justice advocates, and dietitians against processed foods. This seaweed carrageenan, he tells us, will answer the growing worldwide demand for processed foods. Hooray?

The ultimate goal, Holtz writes, is to establish factories in which seaweed juice will be made into bio-stimulants for crops. We know this old story: the sea robbed for the benefit of land. What effect will inshore expansion of seaweed aquaculture, as a crop stimulant, have on the nearshore fish that are a principle source of protein for so many Indonesian villagers?

In the next paragraph we learn that bio-stimulants are actually not the ultimate goal. Holtz misspoke a moment ago. The stimulants are just “a stepping stone.” The ultimate-ultimate goal is biofuels. How can Holtz tout the promise of seaweed biofuels without mentioning what has proven to be the false promise of corn and sugarcane biofuels?

The reason corn biofuels are controversial, Holtz’s seaweed entrepreneur tells him, is that on land “you get this food vs. fuel debate.” (You certainly do.) “But if you could do agriculture in the sea, that would completely change the equation, because there is so much area out there in the sea.” This raises a couple of questions: 1) No food comes from the sea? And 2) How much of that vast area of the ocean is actually suitable for cultivation of seaweed?

Holtz tells us that the “MIT of India” has developed industrial farming methods and a sea combine “that allow seaweed to be grown virtually anywhere in the ocean.” This also raises a couple of problems:

1. For almost a century the conservation movement has been warning against the disasters that industrial farming methods have wrought on the land. No one familiar with history and precepts of environmentalism would use the term “industrial farming” so blithely.

2. The sea combine would allow for seaweed cultivation virtually anywhere in the ocean. Really? Seaweed is benthic and requires shallow water. Most of the ocean is miles deep. Polar seas are frigid and freeze solid in winter. The Southern Ocean is divided latitudinally according to the volume of its howl: the Roaring Forties, the Furious Fifties, the Screaming Sixties. How would you anchor your “chorizos” stuffed with seaweed over deep ocean? How would you keep them from disintegrating in heavy seas? How would you find your farm again on the open ocean after a gale? How would you harvest?

In fact, most of the ocean is unavailable. If by misfortune this contraption, the sea combine, actually proves to work, it would have to do its clanking in the inshore waters that are the most naturally productive on Earth.

The “promise” of seaweed aquaculture includes many more pitfalls than the author recognized.

Ken Brower is the author of many books, including Hetch Hetchy: Undoing a Great American Mistake and Freeing Keiko: The Journey of a Killer Whale from Free Willy to the Wild. A regular contributor to National Geographic magazine, he is a member of the board of directors of Earth Island Institute.


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