Stewarts Family Restaurant Hawaii

A midcentury menu from Stewart's Family Restaurant on Oahu. (Photo: Kyle Van Houtan/NOAA)

Hawaii's fish populations have undergone dramatic changes in the past century, but much of their story has been hidden by a 45-year gap in state fishing records. That's beginning to change, however, thanks to an unorthodox data source: old Hawaiian seafood menus.

Many tourists bring the colorful menus home as souvenirs, often preserving them for decades without realizing they hold valuable environmental data. In addition to these private collections — some of which date back to the 1800s — researchers tracked down vintage menus in archives, libraries and museums, revealing their findings in a peer-reviewed letter published Aug. 1. While menus don't meet the usual criteria for scientific records, they're often the only available clues to past fish populations.

"It's not something that would normally be considered data," lead author and Duke University professor Kyle Van Houtan tells MNN. "But at this point, it's all we have."

Van Houtan, who also leads the National Oceanic and Atmospheric Administration's Marine Turtle Assessment Program in Honolulu, says there's no precedent for using old menus this way. "What we're trying to do is get at historical baselines — what was normal," he says. "And to do that, sometimes you have to get creative."

Photo: Kyle Van Houtan/NOAA

The strategy seems to be working, according to results published in the journal Frontiers in Ecology and the Environment. After analyzing 376 menus from 154 different restaurants, Van Houtan and his colleagues found that reef fish and other near-shore species were common on Hawaiian menus before 1940. By the time Hawaii became a state in 1959, however, they collectively appeared on fewer than 10 percent of menus sampled.

Hawaiian restaurants began shifting toward big, open-ocean fish like tuna and swordfish in the 1960s. These species appeared on 95 percent of menus by 1975, while inshore fish had all but vanished. Changing public tastes may partly explain this, the researchers acknowledge, but their analysis of fishing records and socioeconomic data suggests the exodus of reef fish from menus paralleled declines in their wild populations.

"Back in the 1920s and '30s, these reef fish were on every menu, but now you don't see that at all," Van Houtan says. "Some of that could reflect taste, but people do still eat those fish. Their general abundance in the reef is just nowhere near what it used to be."

The idea to hunt for data in old menus began with separate research on sea turtles, Van Houtan says. After hearing that green sea turtles were once sold in Hawaiian restaurants, he set out to find proof. "I just wanted a photo of turtles on the menu, because that's not really something that's in our consciousness today," he explains. After finally finding a turtle dish among dozens of antique menus, he became intrigued by the idea of restaurants as ecological record keepers. "So I decided to see what else I could find if I just kept looking at menus. And in doing so, that kind of became the story itself."

The Tropics menu Hawaii

Photo: Kyle Van Houtan/NOAA

Some of the menus came from local resources — Honolulu's Bishop Museum, for example, and the archives of a community college's hospitality program — but Van Houtan relied heavily on private collectors. "A lot of it was word of mouth," he says. "People would hear I was looking for old menus and say, 'You should talk to this guy.' I kind of stopped after I got about 500. This was really a side project, and not a project in itself."

In a press release about the research, co-author Loren McClenachan from Maine's Colby College says this kind of creative sleuthing could be useful for an array of other studies.

"Historical ecology typically focuses on supply-side information," she says. "Restaurant menus are an available but often overlooked source of information on the demand side, perhaps a modern equivalent to archeological middens, in that they document seafood consumption, availability and even value over time."

"Most of the menus in our study came from private collections," Van Houtan adds. "They were often beautifully crafted, date-stamped and cherished by their owners as art. The point of our study is that they are also data."

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