Monday, March 23, 2009

Aquaculture News: greenhouse gas emmissions and fish meal substitutes

A lot of interesting discussions have come out of the recent annual meeting of the American Association for the Advancement of Science (AAAS). This one was reported in Science News and concerned the carbon footprint of aquaculture operations.

I am one of those who is a firm believer in aquaculture as a method to meet seafood demands without decimating wild populations, but it is in its infancy and is experiencing all of the growing pains associated with a new technological enterprise. According to the AAAS panel, in the growing/feeding process there are greenhouse gas emissions associated with the type of food used (in addition to harvesting/catching and shipping methods). Monitoring aquaculture operations in several countries, it was determined that when certain types of plant-based meal are introduced, there is a lower level of greenhouse gas emissions. However, not all plant-based meal produces positive results; wheat gluten or palm oil produced higher gas levels.

However, there are others hard at work at other possible beneficial substitutes. Reported in the Coloradoan, a Fort Collins brewery is developing a technique in which a portion of it's brewery waste products can be converted into a fish meal substitute. (Not sure if you end up with drunken fish, though!) The significance of finding a replacement for fish meal is due to the declining populations of anchovies and sardines. These "feeder fish" not only support the fish meal trade but are important prey items for larger fish, all the way up to tuna and dolphins (not to mention its value to low-income human populations).

There are those who say that fish raised on fish meal, as opposed to plant meal, tastes better. This may be due to the different oils found in each. According to the Fish Site, a Brazilian soybean processor is developing a technique for extracting oil from algae which would be high in omega-3 fatty acids, similar to fish meal. An acre of algae can produce up to 42,000 gallons of oil compared to only 210 gallons from an acre of soybean. The company is also looking into methods for capturing the CO2 emissions given off by the processing plant and directing it to the algae which uses it in photosynthesis.

With industrial open water fishing continuing to deplete fish populations worldwide, each stride to improve the efficiency and environmental impact of aquaculture is a great step forward.

Many thanks to for the heads up on these news items.

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