RANCHO SANTA FE, Calif. – Pacific bluefin tuna leave Japan’s coast and swim east at breakneck speed to school in North American coastal waters. Many of them return on nonstop flights from Los Angeles as slabs of fresh toro, the “foie gras of the sea,” fattened, refrigerated and ready for the sashimi knives.
The transformation happens in underwater pens that are 150 feet wide and 45 feet deep, where wild-caught bluefin are fattened on fresh sardines to develop the buttery texture prized in Japan.
Bluefin “ranches,” which offer a reliable source of toro sushi that is higher in oil than lean fish straight off the boat, have popped up in waters from Spain to Australia. In the past decade, Mexico’s Baja California and Southern California emerged as a chief source to the lucrative Japanese market.
“It’s basically an underwater feed lot,” said Philippe Charat, who runs a Mexican bluefin operation from his home in chi-chi Rancho Santa Fe, north of San Diego. “We take something that has very little value when it’s in a can and turn it into a very high-quality product.”
Bluefin, or toro, is richer than the yellowfin, or ahi, tuna typically scarfed in American sushi bars. Top-grade cultivated bluefin regularly fetches more than $10 a pound for wholesale buyers at Tokyo’s famed Tsukiji fish market. One wild specimen once fetched $395 a pound.
Pacific bluefin spawn in Japan’s warm coastal waters and journey east a few years later, arriving off Big Sur and running 1,500 miles south to the tip of Baja California.
The fish are caught several hundred miles offshore and then towed to pens that dot the sapphire bays around the Coronado Islands in Mexican waters near San Diego and Ensenada, Mexico, 70 miles south of the border. The pens are tended by crews who guard against poachers, sharks and sea lions.
Months later, the bluefin are harvested. Divers wrestle the flailing silver-blue tuna onto the tarp-covered deck of an outfitted boat. They are rapidly brained, gutted and bled before being suspended in near-freezing saline water to prevent “burn,” or the buildup of stress-triggered lactic acid that can ruin the fish’s firm, translucent flesh.
Wholesale buyers in Japan, who get the bluefin as little as 72 hours after it’s pulled from the sea, call the Mexican shipments “laxfish” after the initials “LAX” stamped on the manifests from Los Angeles International Airport.
“The Mexican fish has a very good reputation in Japan,” said James Joseph, a tuna fisheries consultant and former head of the San Diego-based Inter-American Tropical Tuna Commission, an international body that regulates tuna fishing in the eastern Pacific. “The water is cool, and they’re feeding them fresh sardines all the time, which gives the fish a sweet taste.”
The key to Mexico’s success lies in the abundant supply of sardines, which has long lured a variety of tuna species to the Pacific coastline, from the relatively rare dark-meat bluefin to the more common white-meat albacore and yellowfin that end up in tins.
San Diego and Baja California became hubs for tuna fishing and canning in the early 1900s, when white-fleshed tuna was marketed as an alternative to chicken.
Rising labor costs and the development of tuna-industry dolphin-safe standards in the 1980s decimated the region’s commercial fleet, sending boats to the far western Pacific waters of American Samoa and Guam.
Enter Charat, 67, a French-born Mexican citizen who left a shrimping business on Mexico’s Gulf Coast and began fishing tuna out of Ensenada in 1983.
Unlike the more common yellowfin species, bluefin don’t run with dolphins, exempting them from catch restrictions. In 1997, after a tour of Australian ranches, Charat went into the bluefin business in the San Diego area, facing a lone competitor who soon bailed out.
In its first year, Charat’s privately held, Ensenada-based company, Maricultura del Norte, netted 30 tons of bluefin. The following season, they took in 60 tons. This winter, Maricultura fattened more than 1,500 tons of fish in two dozen pens anchored in a hidden cove tucked around a point of land south of Ensenada harbor.
The ranches are a lifeblood for the $350-million-a-year bluefin market in Japan, generating waterfront jobs in Ensenada and San Diego. Charat thinks growing worldwide demand for bluefin can help San Diego and northern Baja California regain luster as a tuna capital.
Bluefin stocks in the Atlantic have fallen 80 percent in the past 30 years, prompting the chief European Union fisheries official earlier this year to press for cuts in worldwide catch quotas.
Australian authorities imposed new limits on bluefin catches last October amid concern about dwindling supplies.
A handful of Japanese-owned operators have followed Charat into Ensenada, anchoring pens just north of the harbor. Baja Aqua Farms, which is managed by Australians, keeps pens off the Coronado Islands and brings harvested tuna by boat to a packing facility in San Diego, avoiding long waits at truck crossings on the U.S.-Mexico border.
“They said it could not be done in Mexico because the water was too cold, the area of the fish migration too big,” said Charat. “Now it’s by far the most active thing going on in the region as far as fishing goes.”