In the 1980s, poor rice farmers in Asia and Latin America began digging out shrimp ponds to meet the soaring world demand for seafood. The environmental movement was, perhaps justifiably, aghast. The shrimp farmers had cut down lots of mangrove trees to make room for the ponds. Also, the effluent from the shrimp ponds was substantial, though we have to remember the ocean’s ability to dilute and disarm pollution quickly. Nonetheless, Greenpeace declared, “Shrimp farming has been a relentless destroyer of huge expanses of tropical coastline.”
The Global Citizen talked of “super-dense populations of shrimp . . . treated with antibiotics . . . also with pesticides to eliminate predators and competitors,” and the Worldwatch Institute warned that a “typical shrimp farm produces large amounts of waste, some of it highly toxic.” But the Greens hated wild shrimp trawling even more, and world shrimp demand kept growing exponentially.
Now, the journal Science is offering the shrimp farmers congratulations for “substantial strides in many places to reduce their toll on the marine world.” (“Down on the Shrimp Farm,” Science, 328, 18 June). Science did, however, sniff that the farmers were motivated more by economics than by environmental concerns.
- Shrimp farmers have discovered that mangrove swamps are not good habitat for shrimp; the soil is too acidic. They’ve moved their ponds to less ecologically-sensitive places, and many have replanted the mangroves.
- They’re using “biofloc technology” which cultivates microbes to recycle nutrients and reduce waste.
- Researchers are reducing the fish meal in the shrimp feed to ease wild fishing pressure, substituting mainly soybeans.
- Water exchange between the ponds and the environment has been replaced by aerators, to avoid spreading viruses. Beneficial bacteria now flourish in the ponds and help recycle nutrients.
- A devastating shrimp disease—white spot syndrome—helped drive the industry in the 1990s to a shift into disease-free brood stock, raised in bio-secure hatcheries. Female shrimp are now induced to spawn in captivity, eliminating the need to keep catching new wild brood stock.
- Tiger prawns have proven hardy and fast-growing, producing more pounds of shrimp per hectare of pond. Some shrimp farms are getting yields as high as 100 tons of shrimp per hectare per year—10 times the current average.
Note the parallel between shrimp farming’s progress and the gradual development of the world’s high-yield farming since 1960. Both have become more efficient, taking far less land per pound of food, and the wastes have been disarmed. People are getting their preferred foods at less real cost—and with far less stress on resources.
Perhaps both the shrimp farmers and the high-yield farmers have been motivated more by economics than by concern for the environment. However, as Adam Smith told us in The Wealth of Nations, “It is not from the benevolence of the butcher, the brewer or the baker, that we expect our dinner, but from their regard to their own self interest.”
Shrimp farm production sprang from 100,000 pounds in 1980 to more than 3 million pounds in 2007. Shrimp is now the biggest marine aquaculture product.
It looks like opposing shrimp farming was another Green mistake. Or perhaps their opposition pushed the shrimp industry along the path to become environmentally and economically sound and consumer safe. Most infant industries require time, profits, and encouragement to grow into “good” world citizens and shrimp farmers now certainly seem to be doing their part in protecting the seas of the world.