One might assume that sushi and sashimi have been staples of the Japanese diet for centuries, but in fact the widespread consumption of raw fish is a relatively modern phenomenon. Dependent on the sea to provide the great majority of their protein, the Japanese could not store fish for any length of time before it spoiled, so they preserved it by smoking or pickling. But when refrigerators were introduced to postwar Japan, fish that once were smoked or pickled could now be stored almost indefinitely. As the fishing industry adopted new technologies such as long-lining (using extremely long lines with many baited hooks), purse seining (deploying large nets that can enclose an entire school of fish) and onboard freezers, the circumstances became propitious for an unprecedented modification of Japanese eating habits. The bluefin tuna changed from a fish that samurai would not eat because they believed it was unclean, to maguro, a delicacy that can be as expensive as truffles or caviar. Toro, the best quality maguro, comes from the fatty belly meat of the adult bluefin. Truffles or caviar are expensive because they are rare, but bluefin tuna, previously perceived as inedible, could be found in huge offshore schools and soon became an internationally exalted menu item. In 2001 a single bluefin tuna sold at the Tsukiji fish market in Tokyo for $173,600.
In America—where the thought of eating raw fish was anathema 40 years ago—sushi and sashimi have become commonplace, sold in supermarkets, delis and high-end restaurants. Perhaps the grandest temple to sushi in the U.S. is Masa, a New York City restaurant opened in 2004 by Japanese chef Masayoshi Takayama. With a prix fixe of $350 (excluding tax, tips and beverages), Masa immediately became the most expensive restaurant in the city; a lunch or dinner for two can easily exceed $1,000.
It stands to reason that a fish that can be sold for hundreds of dollars a slice is going to attract fishing fleets. The pell-mell rush to provide tuna for the Japanese sushi and sashimi markets has—not surprisingly—intensified tuna fishing around the world. The Japanese tried to fill their larders (and freezers and fish markets) with tuna that they could catch off their own shores (this would have been the Pacific bluefin, Thunnus orientalis), but they soon observed that the bluefins were larger and more plentiful in the North Atlantic. The buyers for Japanese fish importers became a familiar sight at the docks of American ports such as Gloucester and Barnstable in Massachusetts, ready to test the tuna for fat content and, if they passed, buy the fish on the spot and ship them to Japan.
At one time, researchers believed that there were two separate populations of North Atlantic bluefins (Thunnus thynnus), one that bred in the Gulf of Mexico and stayed in the western Atlantic and another that spawned in the Mediterranean and foraged in the eastern part of the ocean. The International Commission for the Conservation of Atlantic Tunas (ICCAT), a regulatory body established in 1969, based its catch quotas for the bluefin on this two-population concept, setting strict limits in the western Atlantic (where bluefin were becoming scarce as early as the 1970s) while allowing much larger catches in the eastern Atlantic. But tagging experiments—pioneered in the 1950s and 1960s by Frank J. Mather and Francis G. Carey of the Woods Hole Oceanographic Institution and refined in recent years by Barbara A. Block of Stanford University’s Hopkins Marine Station—showed that the bluefin confounds the conventional wisdom. The Gulf of Mexico and the Mediterranean are indeed the breeding areas of the North Atlantic bluefins, but individual fishes can migrate across the ocean, and the foraging grounds of the two populations overlap. Because ICCAT has failed to stop overfishing in the eastern Atlantic, bluefin stocks have collapsed throughout the ocean.