DURHAM, N.C., Aug. 5 (UPI) -- Scientists studying changes in fisheries in Hawaii say they've discovered a unique resource -- colorful restaurant menus tourists bring home as souvenirs.
Researchers at Duke University, with U.S. colleagues, say the menus, some dating back more than 50 years, contain valuable data for tracking long-term changes to important fisheries in the Aloha State.
The menus area being used as part of a project to fill a 45-year gap in official records of wild fish populations in the state's ocean waters during the early 20th century, they said.
"Market surveys and government statistics are the traditional sources for tracking fisheries," Duke researcher Kyle S. Van Houtan said. "But when those records don't exist, we have to be more creative.
"Here we found restaurant menus were a workable proxy which chronicled the rise and fall of fisheries."
The researchers' analysis of 376 menus from 154 restaurants showed near-shore species such as reef fish, jacks and bottom fish were common on Hawaiian menus before 1940, but by its statehood in 1959 they appeared collectively on less than 10 percent of menus sampled.
Restaurants began serving large pelagic species, such as tuna and swordfish, and by 1970 95 percent of the menus contained large pelagics and inshore fish had all but disappeared from their menus, the researchers said.
"The decline in reef fish in just a few decades was somewhat of a surprise to us," study co-author Jack Kittinger of Stanford University said. "We knew at the outset the menus would have a unique historical perspective, but we did not expect the results to be so striking."
While changes in public tastes might explain part of this extreme shift, the researchers said, analysis suggests the disappearance of reef fish from menus paralleled drops in their wild abundance.
"The menus provide demand-side evidence suggesting inshore fish were in steep decline," Van Houtan said.
"Most of the menus in our study came from private collections. They were often beautifully crafted, date stamped and cherished by their owners as art," he said. "The point of our study is that they are also data."