A book about the fish we eat

January 1, 2012

For Christmas Roz gave me Four Fish: The Future of the Last Wild Food, by Paul Greenberg, Penguin, 2010.

Greenberg’s childhood fish stories quickly hooked me. From there I willingly followed him through first-person accounts of the development of salmon farming, sea bass culture, the decline of the cod fishery and its substitutes, and the doomed open water fishery centered around the bluefin tuna.

Salmon became subjects for aquaculture because of their large eggs and easy fertilization.  None of the forty subspecies of Atlantic salmon were particularly appropriate for domestication because they ate too much, swam too fast, and grew too slowly.  It came down to Trygve Gjedrem, a Norwegian sheep breeder, to cross salmon adapted to long migrations up rivers (high fat content) with those from the far north for their rapid growth as juveniles.

The problem Gjedrem faced was to selectively breed a salmon which could be grown on less than the 6 pounds of fish it takes to finish a pound of wild salmon.  Within twenty generations the Norwegians had that ratio down to three-to-one.

No wild salmon live south of the equator, but the fjords of Chile have proven productive for aquaculture. Chile has quickly become the world’s second largest salmon producer.

Domesticated salmon now contribute over three billion pounds per year to our tables, three times wild salmon production.

Greenberg prefers a white-fleshed fillet like that of the largemouth bass or its marine equivalent, the striped bass.  These lazy fish have much less of the strongly flavoured red muscle tissue associated with adrenaline-fueled rushes after prey, and so their flesh tends to be light and flaky.

By the 1970s striped bass and European sea bass had been overfished to the point that the only way to meet the demand for the delicacy was through aquaculture.

The author explains how the European sea bass has had an interesting part in late 20th century politics.  Their victory over Egypt in the Seven Days War in 1967 gave Israel access to the Sinai Peninsula, and with it Lake Bardawil, a shallow lagoon which was an ideal spawning area for European sea bass.

Millions went into research on the domestication of the sea bass, a fish Greenberg insists was a poor choice for the role.  With the European Economic Union, many Euros went to Greece to take advantage of the country’s calm, crenellated shorelines, ideal sites for aquaculture.   The sea bass must be a desirable fish:  Israel wouldn’t give back the land they took from Egypt to farm it, and Greece ran headlong into debt to try to meet the market demand.

Greenberg suggests that there’s an Australian sea bass, the barramundi, which is admirably suited to aquaculture.  It can reach adulthood in fresh water ponds, and on a partially vegetarian diet in the bargain.

But while salmon and sea bass attracted buyers for special holiday meals, the day-to-day food fish for much of the world has always been cod, the ugly bottom feeder with the white, flaky flesh.  Cod’s very abundance has been a big part of its appeal.  But then cod stocks plummeted in the face of industrial fishing, and American and Canadian governments listened to scientists and closed the fishery.

Cod is a terrible fish to domesticate.  Apparently it gnaws its way out of nets with annoying regularity, hates to spawn, and is a huge feeder.

The book is at its best when Greenberg describes the lesser fish which are gradually gaining acceptance to fill the fish-sticks role.  Alaskan pollack is a good fish, though the huge fleet owners have manipulated politicians and quotas and strained the resource.

Supermarkets demand a constant, predictable, enormous quantity of fillets.  Fast food outlets are even more persistent.  For example MacDonald’s makes its fish sandwiches from hoki, a cod-like fish found in abundance off the coast of New Zealand, though they are now under pressure to reduce their reliance on the tasty fish as stocks drop.

With a change of diet a Vietnamese catfish, the Pangasius (known locally as the tra), has been upgraded to American chef’s delight.  Greenberg stresses that this air-breathing filter feeder is a good candidate for aquaculture, especially when scientists have improved its taste by eliminating the algae which causes fresh-water fish to take on a muddy taste.

The ubiquitous African tilapia has made great strides as a cod substitute.  This filter feeder requires no additional feed in many aquacultures and reproduces with abandon.  (Not to worry, Canadians:  it dies if the water temperature gets much below 50 degrees F.)

In the 1960s the world decided that whales are wildlife, not food.  Of course the green revolution with its oil-producing seeds for margarine rendered whaling uneconomic, but for the most part mankind turned away from the killing of whales when they could no longer ignore their sentience.

But the bluefin tuna is a warm-blooded animal, as well.  This sushi favourite commands enormous prices and the 700-pound monsters have been hunted to depletion.  Even more insidious, Greenberg suggests, is the netting of juveniles in the Mediterranean to raise to maturity in pens for the market.

Off the coast of Hawaii, on the other hand, Greenberg tells of a dive on deep-water pens where,  “Without any selective breeding whatsoever, the amount of fish required to produce a pound of kahala ranges from 1.6:1 to 2:1, ten times better than the feed conversion ratio for bluefin tuna (233).” And they spawn constantly.    Renamed Kona Kampachi for the sushi market, the kahala is gaining acceptance with chefs and consumers. Greenberg suggests it’s time to end the bluefin fishery.

For its insight and information Four Fish belongs on the bookshelf of every serious cook or fisherman.  It’s also a fine read.


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