A tuna steak at the Pike Place Market was more expensive than their halibut. Halibut was more expensive than cod. Cod was more expensive than rockfish. Rockfish was the cheapest. Therefore, I ate rockfish. I only dreamt of tuna. Fish prices are largely determined by rarity and as tuna and other species become overfished and expensive, it makes sense to start eating other, more abundant kinds.
Meanwhile, three researchers from Duke University wanted to know what fish populations in Hawaii used to look like. But government data and market surveys failed to provide enough information. So they hit on another market proxy – seafood restaurant menus.
The team analyzed over 300 menus from more than 100 restaurants dating back to at least the 1940’s. Most of the menus had been kept as souvenirs or art and were donated from private collections. The menus revealed that back in the 1940’s many restaurants were still offering local or reef-dwelling species, but as time wore on these were slowly replaced by larger, oceanic fish such as tuna and swordfish. By 1970, most restaurants had stopped offering reef fish altogether.
This sudden decline was striking, but the numbers seemed trustworthy.“Historical ecology typically focuses on supply side information,” said Loren McClenachan, who co-authored the study. “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.”
Population studies are important tools for both ecological studies and the fishing industry as a whole.