When you are eating a pan-fried fish filet, do you think about where all the leftover parts-heads, tails, bones, skins, scales, and internal organs go?
In 2008, 115 million tons of fish were used as human food, according to the Food and Agriculture Organization of the United Nations. If all the byproducts from fish account for about 10% of the whole body weight, then there were about 11.5 million tons of fish byproducts! What happened to them?
Until ten years ago it was common to dump the fish waste to the lake and ocean. This has created several problems for various ecosystems and thus drew scientists’ attention. The simplest solution they came up with is composting. In the compositing process, the fish waste is put in a garbage bag and mixed with plant waste for fermentation over a certain period of time, during which the microorganisms in the pile use the waste and convert it into rich humus.
Another solution is recycling the waste. In other words, reusing the waste for the sustainable production of human food and animal feed. There are many products we can make out of the fish waste. For example, the fish skin, bone, scale, fin, and bladder are good sources of fish gelatin, which provides an alternative for the mammalian gelatin extracted from cattle bones, cattle hide, and pork skin.
Not only does the alternative fish gelatin protect our environment through better waste management, but it can also be used as a kosher food ingredient, while mammalian gelatin cannot.
Besides using fish waste for human food, scientists are also studying how to effectively turn the fish byproduct into fish food. Fish farmers used to catch fish from the wild stock to feed the cultured fish, but the open access to the wild stock has caused overexploitation of feedstuff for farmed fish. This has limited the development of aquaculture.
Now aquaculturists have started to actively look for ways to replace fishmeal with animal byproducts. This way, the byproducts would be reused in yet another way, and the production of fish would be sustainable.
Clara Zhang is a graduate student. She can be reached at email@example.com. The Missing Link: Sustainabillity appears on appears on Mondays.