Monday, 23 January 2012

The Fish on Your Plate

The Fish on Your Plate by Paul Greenberg is a book that might change the way you look at fish.

He approaches the subject as a fisherman, and starts by recounting his own experiences of disappearing fish stocks, and how local fish on fishmonger’s slabs have been replaced by just four globally-traded species.

We have just passed the point where we now consume more farmed fish than wild fish. Soon wild fish may no longer be regarded as economically viable or, more probably, an expensive luxury that only the wealthy can afford. Fish domestication is happening now, rather than in the distant past, and is compared in the book to the domestication of animals (cows, pigs, sheep and goats) and birds (chickens, turkeys, ducks and geese). You might think that the choice of fish to domesticate in this modern age has been governed by scientific and rational considerations. Think again, says Greenberg.

The book is structured around the big four universal fish: tuna, salmon, sea bass and cod. Tuna is described here as the last great gold rush of wild fish. One last sushi binge before wild fishing as we have known it comes to an end. Tuna is a stateless fish, travelling over long distances, and so is difficult to manage in a sustainable manner.

Salmon represents the first wave of aquaculture. The model used was taken from agriculture: industrial monoculture. Salmon farming has been commercially successful, but it has left in its wake a raft of problems. Salmon farms are environmentally polluting, high levels of disease can occur in the farmed fish, escaped fish are breeding with wild salmon to the detriment of wild populations, and high levels of PCB are found in farmed salmon (due to them being fed pellets made from small fish trawled from the sea bed). Government advice is to limit consumption of farmed salmon, for example, to once a week, because of the chemicals it contains. Greenberg suggests that a way forward with salmon, and aquaculture generally, is to move toward less-intensive polyculture farming, involving the cultivation of seaweed, mussels and other species together to strike a more ecological balance and reduce pollution and disease.

Sea Bass is a less than obvious choice for a farmed species. It was, in fact, very tricky to domesticate. Over many years, European scientists worked out that the juvenile diet of phytoplankton could be replaced by rotifers, while artemisia (sold to kids as ‘sea monkeys’) could supplement the diet of just-hatched fish and improve what is naturally a very high mortality rate. Hormone delivery and precise control of photoperiod were other necessary steps to successful domestication. Once the techniques were mastered, however, farmed sea bass quickly became a globally-traded fish. Another upside of all the scientific work done is that there is a framework in place for domesticating practically ever other fish in the seas. On the downside, like salmon farming, adult sea bass are fed pellets made from fish dredged from the oceans, with around 3lb of fish required to produce 1 lb of fish. Sea bass domestication was a great leap forward for fish farming, but Greenberg suggests greater success lies ahead with species that are easier to breed and have better food conversion efficiency.

Cod is the workaday fish that has disappeared. Because it has been so popular, efforts have been made to farm it, using the advances made for sea bass (e.g., rotifers, artemisia). However, cod takes too long to mature and proved very expensive to farm – you just don’t get meat for your money, concludes Greenberg.
Instead of choosing fish for which there is a known market, Greenburg suggests, we need to look at previously unknown species that tick all the right boxes in terms of breeding ease, food conversion efficiency, and ability to thrive in sustainable low-pollution aquaculture. Tilapia is cited as a good choice in many respects. He suggests a number of fish, including barramundi and kahala (Almaco Jack), which you may be hearing much more of in the future.

This is a well-researched (although, note to publisher, geosmin and not geosim on page 182), highly readable, and thought-provoking book. I highly recommend it to anyone who has ever thought about why we eat the particular fish species we do, and not most of the other perfectly edible species in the sea.

Greenberg, Paul (2010) The Fish on Your Plate. Penguin Books.


Another book review you might enjoy:
The Noma Cookbook:
http://sfnottingham.blogspot.com/2011/10/noma-cookbook.html

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