Wednesday, November 28, 2012
Written by Drew McCullough/Scicats
When you eat salmon or carp or tilapia, you might imagine that the fish had once been swimming free in the wild. In recent years, however, more and more of the world’s seafood have grown up on a farm.
In fact, seafood is the most common source of protein worldwide, and more than half of it is farm raised, according to Dr. Kevin Fitzsimmons. Tilapia is the fourth most widely consumed seafood in the United States, and virtually all these fish came from a farm.
Farm-raised fish will soon surpass wild fish as a food source. “In a few years,” Fitzsimmons said, “people will look back at television shows like ‘Deadliest Catch’ and say, ‘How quaint. They used to go fishing out there in the ocean for food.’ All seafood will come from farmed operations, and it’s going to happen in the near future.”
Fitzsimmons is one of the world’s leading experts in tilapia production techniques. A research scientist in Soil, Water and Environmental Science at the University of Arizona, he was elected president of the World Aquaculture Society in 2004.
He recently developed an integrated aquaculture irrigation system that is the most efficient way today to raise tilapia while protecting the environment and using as few natural resources as possible. He presented his findings at the World Ocean Forum in Busan, Korea. The proceedings were published this year.
In this self-sustaining system, the fish are raised in ponds along with a variety of vegetables and herbs, such as lettuce, basil and cilantro. Wastes from the fish fertilize the crops. Other crops, such as algae, improve water quality and provide the fish with filtered water.
Agricultural wastes are used to fertilize the ponds or as a food source for the fish, thus eliminating additional feeding costs. These agricultural wastes include byproducts from distilleries, breweries and cotton production.
Raising both fish and crops in an irrigation system is known as aquaponics. This is the most efficient, up-to-date way to farm tilapia because it incorporates elements of both aquaculture and agriculture and minimizes the negative side effects of each system on its own.
Fish and shrimp aquaculture systems typically depend on fishmeal as a feed ingredient. Fishmeal is mostly derived from wild-caught fish and the carcasses of processed fish. This process can be harmful because it rapidly depletes the ocean’s supply of certain species of fish.
In addition, the used water from an aquaculture system is disposed of as effluent, which is dumped into a natural body of water. This process can be harmful because it decreases oxygen levels in the natural body of water, which can also decrease the supply of fish.
Harmful side effects of some agriculture systems include the need for chemical fertilizers and large amounts of natural resources, such as fossil fuels.
Although several types of fish are raised in aquaponic systems, tilapia has been “the greenest of aquaculture crops,” Fitzsimmons said.
That’s because so many tilapia farms use aquaponics and other integrated farming systems. “Tilapia is grown in over 100 countries around the world,” Fitzsimmons said, “and is going to become the equivalent of chicken in the poultry industry.”
Every year, tilapia farmers from all over the world consult with Fitzsimmons about how to use water more efficiently, make more money and be more sustainable. He has worked with tilapia farmers in the United States, Mexico, South America, Southeast Asia, Israel, Turkey and Africa.
Fitzsimmons also helped two of his former students establish Arizona’s largest tilapia farm—Desert Springs Tilapia in Dateland, Ariz.
Fitzsimmons’ work never is complete. He teaches an aquaponics short course through the UA every April, and he continues to research new ways to maximize the global potential for seafood production in aquaponic systems.
Drew McCullough is a student at the University of Arizona in Prof. Carol Schwalbe's Science Journalism Class