A major problem with fish farming is water pollution. Fish waste, uneaten feed and fecal matter accumulate in the aquatic environment affecting the farm and neighboring water supplies. It is estimated that up to a ton of waste is produced for each ton of fish raised. Most of the waste is in the form of organic solids and inorganic nutrients such as nitrogen and phosphorus causing “over-nitrification” and the spread of algal “blooms” – massive blankets of green slime on the water’s surface that precipitate bacteria growth, deplete oxygen, and kill much of the life in the water below.
In 2001, shrimp surpassed canned tuna as America’s favorite seafood. Today, more than one billion pounds of shrimp are imported from foreign farms. While shrimp is now the most popular and widely traded seafood in the world, its rise in popularity and profitability is shadowed by its environmental costs. A solution, Integrated Multi-Trophic Aquaculture (IMTA), is a practice in which the by-products (wastes) from one species are recycled to become inputs (fertilizers, food) for another. For example, shrimp farming is combined with shellfish and seaweed farming to create balanced systems for environmental sustainability.
Scientists from Canada have been growing mussels and kelps adjacent to salmon cages in the Bay of Fundy since 2001 and are documenting its IMTA data. The rigorously examined mussels are free of contamination and of any “fishy” taint from neighboring salmon. Moreover, this nutrient abundance is having a positive impact on the growth of both species: the mussels reach market size 8-10 months earlier than normal and the kelps grow greater by 46%. Hopefully, this economically attractive and ecologically sustainable concept will be adopted globally. Consider: Expanded research and collaboration by scientists across the globe employing next generation Internet technologies for researching the efficiencies of other native shellfish filter feeders and kelp species for IMTA in developing countries.