Open Ocean Cage Shrimp Farming


The global shrimp market weighs in around 6 million tons annually generating about $13 billion of the total $50 billion global mariculture industry.  Shrimp are diverse sea creatures found in nearly all geographical regions of the world and thrive in habitats ranging from tropical estuaries to the open ocean.  Industrial shrimp farming began in 1980 and jumped to five percent of global shrimp production in a mere two years.  By 1990 farming produced 25 percent and the boom has continued so that today 60 percent of shrimp is farmed.  While shrimp is now the most popular and widely traded seafood in the world, its rise in popularity is overshadowed by its social and environmental costs.  Not many shrimp consumers have heard of mangrove trees, let alone understand their ecological value.  These gnarly, tangled giants grow throughout the tropics along estuary banks.  The trees' unique roots absorb both salt and fresh water and anchor one of nature's most productive ecosystems.  These trees buffer the land against hurricanes, collect sediments and other pollutants from rivers, and sustain habitats for numerous creatures.  Mangrove trees also are more efficient photosynthesizers than almost any other plant, creating a steady supply of nutrients for the tiny creatures at the bottom of the food chain.  One study found that for every acre of mangroves lost, wild harvests of fish and shrimp drop by 676 pounds per year.  

Nearly half the loss of mangroves in the world has been attributed to shrimp farming.  Shrimp farms in many developing countries are only productive for a few years thereby leading to a continuum of destruction of coastal areas.  Shrimp farms also depend on staggering amounts of antibiotics, fungicides, algaecides and pesticides polluting and robbing precious drinking water.  Global coastal shrimp fisheries are struggling to cope with collapsing shrimp stocks and record-low prices.  Large trawlers offshore compete with artisanal fishing in bays and estuaries, further depleting the resource base, engendering poverty and spurring conflict.  Land-based shrimp farming only exacerbates the situation through disputes over land use and water contamination from toxic effluents.  Additionally, land-based shrimp farming results in degradation of coastal habitats.  Unlike conventional shrimp capture and farming methods, Open Ocean shrimp farming in cages features the following benefits: no by-catch; no destruction of mangroves or impact on benthic ecosystems; no use of antibiotics, herbicides or pesticides; low levels of detectable waste; low energy use and carbon emissions; and a high level of resilience to climate change.  While in its infancy, Open Ocean shrimp farming is a promising concept, which recently produced 13 tons, or about 130,000 shrimp from one 3,600 cubic meter cage in La Paz, Mexico.  This is the average yield from a trawler fishing a 6-month shrimp season.  Moreover, the Feed Conversion Ratio (FCR) for this pilot program was .15 and the marine scientists monitoring the project believe the FCR can be reduced to zero - the Holy Grail for sustainable mariculture.