Part 3: Pizza Crusts and Hot Dogs as Fish Food
Published: February 6, 2018
By Bobby Bascomb
(Photo: SUNY College of Environmental Science and Forestry)
(stream/download) as an MP3 file
Pizza crusts and hot dogs - if cafeteria food is good enough for college students, is it also good for aquaponic fish? Closing the food waste stream. (broadcast 111202)
GELLERMAN: Our voracious appetite for seafood vastly outstrips the world supply. Globally, fish stocks are in steep decline. As a result, fish farming or aquaculture is booming – and so is a relatively new industry: aquaponics, growing fish and plants together in a closed symbiotic system.
In Syracuse New York, far from the ocean, a young scientist is experimenting with aquaponics - feeding fish with a... well, let's let Living on Earth’s Bobby Bascomb tell you the story. She has the latest installment in our series: Go Fish: Striving for Sustainability.
[CAFETERIA SOUNDS, MUSIC: “I WAS BORN THIS WAY” BY LADY GAGA.]
BASCOMB: The State University of New York’s College of Environmental Science and Forestry in Syracuse serves meals buffet style.
AMADORI: They have a salad bar, a pizza bar, you know, your stir fry bar, taco bar.
BASCOMB: Michael Amadori is a graduate student here majoring in ecological engineering.
AMADORI: There’s a huge array of different samples of food to choose from.
BASCOMB: All those choices lead to a lot of leftovers. In 2009, the university composted 200,000 pounds of food waste.
AMADORI: FDA regulations, a lot of this stuff after it’s been out, cannot be used again and again and again. So, after being used for a day, anything that’s left at the end of the day is trash. They get a box of cucumbers, and two of the cucumbers have like soft or moldy spots, that whole box of cucumbers is now trash.
BASCOMB: Roughly 40 percent of all food produced in the United States is wasted. So Amadori came up with a thesis project to convert some of his University’s waste into a valuable resource…. fish food.
AMADORI: The cafeteria usually closes around 8:00 pm, so I’ll go there right around 8:30. So, what I’m getting a lot of times the left over meat off the grill is still warm. I’ve contemplated making myself a sandwich off some of the stuff I find back there!
BASCOMB: He doesn’t make himself a sandwich, but he does feed the meat to his fish. In general he keeps an eye out for any foods they might like.
AMADORI: This corn and bean salsa right here, I mean, that’s like gold right there. If I get some of that, I’ll put all of that in the food - the corn, beans.
BASCOMB: All the food he collects, except dairy, goes into the grinder to make a mush the consistency of play dough. Then he squeezes it through an extruder to make spaghetti shaped strands that are baked, dried, and broken into bite sized fish pellets.
[WALKING SOUNDS, DOOR OPENS]
BASCOMB: Amadori leads the way across campus to a small greenhouse where his thesis experiment is growing and eating.
AMADORI: So, in each fish tank there’s 50 gallons of water and about 19 tilapia fish.
BASCOMB: There are 6 tanks in total, and above each tank is a 50 gallon drum cut in half and filled with gravel. That’s where Amadori cultivates the other half of his experiment.
AMADORI: Aquaponics is the combination of aquaculture and hydroponics. You raise fish in your standard fish tank like people have at home. But instead of using those commercial filters that clean the water, you pump the water up into a hydroponic grow bed which cleans the water just like the commercial filters, but you also get value added produce out of it.
BASCOMB: The fish deposit their waste in the water. That waste acts as a fertilizer for Bibb lettuce plants, and the water filters through the gravel to drip back to the fish.
[RUNNING WATER SOUNDS]
BASCOMB: Tilapia are omnivorous. Amadori feeds the cafeteria diet to the fish in three tanks. Fish in the other three tanks get the industry standard corn-based fish food.
AMADORI: I like to say that there are three main ingredients: ground corn, ground fish and ground up Flintstone vitamins. So it’s a vitamin and mineral pre-mix and just a corn-based feed and a lot of fish.
BASCOMB: It’s all that fish in aquaculture feed that worries Amadori. He says it’s not sustainable.
AMADORI: We’ve pretty much outfished all of the main commercial fishes in the ocean, so what we’re doing now is we're harvesting their food. The smaller based fish that is feed for the haddock, feed for the tuna, feed for the salmon, we’re taking their feed and grinding it up just so we can grow fish in aquaculture setting, so it’s not the most sustainable practice.
BASCOMB: Sustainable or not, fish love it. Amadori takes out a plastic container of food.
[PELLETS SHAKING IN BOX UNDER TRACK]
BASCOMB: And shakes some into the tanks. The fish immediately come to the surface and gobble it up.
AMADORI: The commercial food has been formulated after decades of research so it is catered exactly to what the fish want to eat. They really like this. It’s like they get to eat their favorite cereal every day.
BASCOMB: We’re feeding them Fruit Loops basically here.
AMADORI: Yup, the sweet delicious cereal that they love.
BASCOMB: Amadori says the fish don’t like cafeteria leftovers as much.
BERNSTEIN: My concern about taking the food waste stream from a university is that that doesn’t necessarily translate into something that is consumable by a fish.
BASCOMB: Sylvia Bernstein wrote the book Aquaponic Gardening: a Step by Step Guide to Raising Vegetables and Fish Together. She says cafeteria tacos and stir-fry might not provide all the necessary nutrients.
BERNSTEIN: Fish need vitamin C. If fish don’t get enough vitamin C they get something called broken back syndrome. Another thing that can happen is there have been peer reviewed studies that if you feed any sort of mammalian protein to a fish that they get something called fatty liver disease that can kill them as well.
AMADORI: I’ve done analysis of the pellets and they're comparable in terms of protein content, fat content, carbohydrate content, and mineral content to the commercial fish feed. So, in terms of their basic nutrient requirements, they’re being met.
BASCOMB: Aquaponics expert Sylvia Bernstein thinks it’s a good idea to use food waste, but there could be an even better way.
BERNSTEIN: The alternative would be to take this waste stream and put it into a vermicompost or worm process where the worms are now breaking down the food waste. They will create vermicompost, which would be tremendous for the school grounds and the worms are something that is excellent for the fish.
BASCOMB: Pelletized pizza or compost worms, either way the fish food is basically free. So, even though the cafeteria fed fish grow more slowly, Amadori says it still makes economic sense. Furthermore, the fish really aren’t the most profitable part of the system.
AMADORI: In one week I’m getting three heads of lettuce in that fish tank. Between the whole system, I’m getting 18 heads of lettuce a week. And that organic lettuce sells for three dollars a head. That’s where your real moneymaker is.
BASCOMB: And aquaponics is a very efficient system. It uses about one tenth as much water as traditional farming, making it ideal for areas prone to drought - much of Africa, the US Southwest, or Australia.
AMADORI: You can also grow tomatoes, cucumbers, just about any other crop you can grow in your garden - outside of root vegetables - you can grow in an aquaponic system.
BASCOMB: Amadori is eight months into a year-long project. When he’s finished, some of his fish will be analyzed and compared to the commercially fed fish as a food source. But he’ll still have a lot left over for dinner.
AMADORI: When I’m done, we’re going to be eating lots of fish tacos, I guess. I’ve put in a year of hard work growing these fish in this system and I intend to eat them all and savor the flavor.
BASCOMB: For Amadori, this project is a possible way to kill two birds with one stone: reduce food waste and grow sustainable food. Though he’ll spend a year caring for his tilapia, they are anything but his pets. For Living On Earth, I’m Bobby Bascomb.
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