For most restaurant diners, a menu represents only a pleasingly difficult decision of what to eat (or, in some cases, a soon-to-be empty wallet). Yet for tourists in Hawaii throughout the first half of the 20th century, menus represented a colorful way to remember their time in an exotic land, and many diners took their menus back with them to the mainland. For marine ecologist Kyle Van Houten of Duke University, these souvenirs serve an unexpected purpose: by studying the changes in the availability of different fish species on menus from the islands, Van Houten and his colleagues were able to estimate the changes in the local fish populations over time.
Ecologists usually employ more precise information from commercial fisheries and governmental organizations to estimate changes in the ocean, but as Van Houten explains, fishery records are spotty before Hawaii’s statehood in 1959, and “there is a gap in commercial fishery data that we need to fill.” Menus from before 1940 commonly listed a variety of fish collected from near the islands’ shores, including reef fish, jacks and bottomfish. By Hawaiian statehood, however, these species were present on less than 10 percent of menus. Van Houten emphasizes that “the decline didn’t occur because of changes in people’s tastes in seafood,” citing interviews with native Hawaiians who reminisced about previously common reef species like goatfish. “The demand was there, but the fish weren’t.” The menus record the responses of restaurants to these changing times, with large, oceangoing fish such as tuna and swordfish becoming more prevalent entrees as the century progressed. These “large pelagics” appeared on 95 percent of menus by 1970, while the near-shore species had almost entirely vanished.
Although the menus are unable to explain why the changes occurred, Van Houten argues that tourism and agricultural development had the largest impacts on fish stocks. The present situation is little better; Conservation International reports that nearly 75 percent of Hawaii’s near-shore fish stocks are depleted or in critical condition, largely due to “[c]oastal development, land-based pollution, and destructive and illegal fishing.” Reef species are particularly vulnerable due the additional stresses of global climate change, which can cause coral bleaching and disrupt reef ecosystems. Mass bleaching has already been observed in the northwestern Hawaiian Islands, with more events predicted to occur.
Conservationists concerned about the future of the fisheries have begun to look into the past for the effective management strategies of native islanders. A recent study suggests that harvests under native management were five times that of current levels, and more importantly, that these catch rates were maintained for hundreds of years. This success has been attributed to aggressive management techniques such as the “kapu” system, in which fishermen found on a reef forbidden by the local ruler could be blinded or even put to death. While John Kittinger, the author of the study, acknowledges that these punishments were excessive, he stresses that “it’s easy to see there’s room to tighten up today’s enforcement efforts.”