Why do we eat so much tuna?

Children weighing under 55 pounds should eat tuna no more than once per month, according to a report released recently, because of concerns over mercury. The controversial recommendation is stricter than that proposed by the FDA, and some experts say we should eat even more tuna, although it's already a lunchbox -- and for Minnesotans, a hot-dish -- staple.

Why did Americans fall for tuna?

Because it's cheap and bland. Most of the tuna consumed in 19th-century America was imported in cans from France and served to European guests at upscale East Coast restaurants. Mainstream Americans considered the fish too gamey, until a cannery in San Pedro Bay, Calif., figured out that the steamed white meat of albacore tuna has very little flavor if you drain the fish's own oil and can the meat with olive or cottonseed oil instead.

The company began marketing the product as a chicken alternative in 1907. It distributed thousands of free recipe booklets, which contained mostly classic chicken or canned salmon recipes with tuna as a substitute. Americans found that tuna's flavor was hardly noticeable in the right sauce, and sales began to rise.

The tuna revolution really took off during World War I. European countries, and eventually the U.S. government, bought the inexpensive canned fish to feed the troops. (Uncle Sam was so desperate for protein during the Great War that the government even tried to push whale as a beef substitute.) Returning soldiers continued eating tuna, which displaced salmon as America's fish of choice by the 1940s, and fishing boats had to venture farther and farther from shore to satisfy demand.

Canned tuna also owes its early success to El Niño. The California Fish Co., which popularized canned tuna in the United States, originally specialized in sardines. A change in the weather in 1903, however, pushed the tiny fish out of San Pedro Bay, forcing the company to experiment with substitutes like halibut and rock cod, eventually settling on albacore.

The product faced a serious marketing challenge. The only Americans who had ever heard of albacore were West Coast sport fishermen. California Fish Co. decided to label albacore as tuna, even though scientists of the day considered the two fish taxonomically distinct. While scientifically questionable at the time, the gambit worked, and Americans came to think of albacore, and not the better established bluefin and yellowfin, as the definitive tuna fish. The company was vindicated decades later, when scientists reclassified albacore as a tuna.

That wasn't the last taxonomic controversy in the commercial tuna industry. When albacore became scarce near U.S. coastlines in the mid-20th century from overfishing, canneries sought to sell the skipjack as a substitute. Skipjack belongs to the same taxonomic tribe (Thunnini) as albacore, but not to the same genus (Thunnus). The government ultimately decided to let the industry market skipjack as "light tuna," arguing that scientific and commercial names don't always have to agree.

Americans still eat twice as much tuna as salmon, their second-favorite fish. Tuna's share of the fish market has declined steadily over the past 25 years, however, and salmon could reclaim the title of America's favorite fish in the next decade or two.

In what might be considered the Official State Dish in Minnesota, however, there's really no substitute for tuna. "To many of us, tuna is hot dish, rather than tuna salad or tuna melts," said Ann Burckhardt, author of "Hot Dish Heaven." "Hamburger is more common in hot dish, but tuna is probably second in line, way ahead of salmon."

Burkhardt added that she could see problems for families that heed the new warnings. "I think there are mothers who are like my mother, who said, 'This is Tuesday, it's macaroni and cheese day,'" she said. "A lot of women who consider cooking a chore do that and maybe they are doing that because it's cheap. We're in a bad economy.

"And I've worked a lot with food shelves, and those bags more often than not will have three cans of tuna."

Some industry insiders blame dolphins for tuna's loss of market share. To earn the "dolphin-safe" label, fishermen have focused on skipjack, which don't typically associate with dolphin pods. The change may have had commercial costs, though: Many people prefer the taste of albacore to skipjack, and the difference in taste could be driving customers away.

At the Twin Cities' most popular seafood retail emporium, customers rarely ask for skipjack or albacore, but they do often request other types of tuna, said Coastal Seafoods general manager Tim Lauer. "Basically it's three groups. There are people who want ahi, which is yellowfin or bigeye. There are people who specify bluefin, which they usually want for sushi. And there are people who just say 'I want tuna.'"

Lauer added that many of his customers express concern about mercury. "Mercury is a big issue in general with fish," he said. "But most modern research shows unless you're subsisting on large predatory commercially caught fish, like shark or lake trout, there's not much danger of mercury poisoning."

Staff Writer Bill Ward contributed to this report.