Seeker Blog

Economist Jeff Sachs promotes aquaculture and global fisheries controls in the July Scientific American. Included are some interesting factoids — e.g., China is now producing about 2/3 [by weight] of global farmed fish. I’ll look into this further to verify how much of that Chinese production is “good fish”, like carp or catfish raised on plant matter, as opposed to carnivore “bad fish”, like salmon — raised on other fish species. Farmed salmon consume between three and five times their market weight in fish meal so they are a significantly net-negative food source.

…Into the breach has arrived the Blue Revolution, first in China, and now in many other parts of the world. Aquaculture yields have increased from around two million metric tons in 1950 to almost 50 million metric tons today. Thus, even though the global fish catch peaked in the late 1980s, aquaculture has enabled a continuing rise in human consumption of fish. China now accounts for around two thirds of total aquaculture production worldwide by weight and roughly half by market value.

Fish farming in China is of course an ancient activity, with several carp species grown among rice fields for thousands of years. The inter-mixing of rice production with fish farming, rather than with animal husbandry as in Europe and the Americas, made good ecological and economic sense in densely populated China. A cow requires around seven kilograms of feed grain for each kilo of meat, while a carp requires around three kilos or less. Fish farming economizes on feed grain, and of course on the land area needed to produce it.

The exciting news, however, is that recently Chinese scientists have both improved the efficiency of aquaculture and revolutionized the range of species that can be farmed. An insightful study by coastal ecologist Carlos Duarte and his colleagues in the April 7 Science documents the dramatic rate of domestication and commercialization of marine species. Of the more than 400 farmed marine species, as many as 106 have been domesticated in the past decade alone. In contrast, there has been almost no concurrent increase in the number of domesticated land species.

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