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Beyond Malthusian pessimism: Aquaculture as a milestone in human history

About 12,000 years humans initiated the domestication of plants and animals in the fertile crescent thereby developing the capacity to control the production of their food. The development of agriculture is a fundamental milestone in the history of humanity, conducive to a re-arrangement of societies, the development of cities, complex economies and taxes and even the development of writing, as the oldest known writing, the Umm el-Qaab clay tablets, dated 3400 BC to 3200 BC, are an account of agricultural yields and the corresponding taxes.

Meanwhile, we have continued to engage with the oceans in a primitive way, delivering food from the oceans through harvesting of wild stocks of fish and marine organisms, as hunters-gatherers, so our interaction with the oceans continue to be Paleolithic in Nature.

This is now changing. About 50% of all marine fish currently consumed derive from aquaculture, which now provides 30% of all marine food products, and has allowed the yield of marine food to continue to increase despite the decline in wild captures by about 10% over the past 20 years (Duarte et al. 2009). Indeed, there is no longer a margin to increase marine fish yield through harvesting of wild stocks, as most fisheries are overexploited and the challenge to reach sustainable levels requires that catches be lowered by at least an additional 20%. Indeed, fisheries should be reduced even further as aquaculture develops the capacity to produce a greater share of our marine food requirements, to eventually bring fisheries to a comparable residual activity as that of hunting.

Although marine aquaculture originated in Egypt 4,000 years ago, the domestication of marine species is a recent phenomenon, progressing at an unprecedented rate, with over 300 marine species domesticated, and more than 10 additional species being brought into aquaculture every year (Duarte et al. 2007).

Meanwhile, increased human population continues to drive a growing demand for marine food products. Marine food is not just supplementing food production on land, as the consumption of marine food delivers demonstrated benefits to human health, through the supply of healthy fatty acids, such as omega 3, as well as oligo-elements, such as iodine and selenium, and is a comparatively safer source of protein than livestock products. Health organizations typically recommend two meals of seafood per week, effective in improving our coronary, mental and reproductive health.

Aquaculture is the only avenue to meet the growing demand for seafood. However, aquaculture, as practiced today, is often not sustainable. Fin-fish aquaculture is dependent on the supply of fish flour and oils from wild catches, consuming 33 million catches of wild stocks for oil and flour to deliver 35 million tons of fish per year. In addition, excess feed generates problems in the environment and escapees from aquaculture may turn into invasive species or affect the genetic composition of wild stocks (Holmer et al. 2008). Aquaculture need to progress to achieve sustainable practices, which is an achievable target. With simple and appropriate measures, which I will describe in a subsequent post, marine aquaculture has the potential to shift from being a problem to become a positive force in the marine environment (Duarte et al. 2009).

Whereas the production of meat products from livestock represents 2% of food production, it consumes 45% of all water used by agriculture. Shifting the production of the animal protein component of our diet to the ocean can free most of this water to be used to produce additional agricultural products, while delivering healthier diets. Marine aquaculture does not require either significant freshwater nor arable land, the two major bottlenecks for further growth in global food production.

I counted 67 species for sale in this fish shop in Mallorca (Spain), of which 37 derived from aquaculture. Photo: Carlos M. Duarte

Integrating food production on land and the oceans has, thus, the potential to overcome current Malthusian ceilings and help provide an answer to the “9 billion people question” (i.e. how to feed them). In doing so, we must be intelligent and avoid the major errors made as agriculture and livestock production developed, with a big toll on the environment and human health.

Ten thousand years later we have progressed enough in our understanding of the biosphere and the oceans to recognize our capacity to impact on the environment and the consequences of these impacts on our own health and well being. We are now prepared to shift the way in which we interact with the oceans and to do so to deliver wealth and well being while improving the state of our oceans.

References

Duarte, C.M., N. Marbà, and M. Holmer. 2007. Rapid Domestication of Marine Species. Science 316: 382-383.

Duarte, C.M., M. Holmer, Y. Olsen, D. Soto, N. Marbà, J. Guiu, K. Black and I. Karakassis. 2009. Will the Oceans Help Feed Humanity? BioScience 59: 967–976.

Holmer, M., Black, K., C.M. Duarte, Marbà, N., Karakassis, I. (Eds.) 2008. Aquaculture in the Ecosystem. X, 326 p., Springer Netherlands.