Ancient Hawaiians Caught More By Fishing Less
Centuries ago, Hawaiians caught three times more fish annually than scientists generally consider to be sustainable in modern times — and maintained this level of harvest for more than 400 years, researchers report in a new study in the journal Fish and Fisheries.
The findings could be instructive for agencies that enforce fishing limits in overfished waters around the globe.
A school of manini fish pass over a coral reef in Hanauma Bay in Honolulu.
Native Hawaiians caught about 50 percent more fish than modern fleets catch today in both Hawaii and the Florida Keys, the two largest reef ecosystems in the United States, said a co-author of the study, Loren McClenachan, a fisheries researcher at Colby College in Waterville, Me.
Hawaiians harvested about 15 metric tons of fish per square kilometer of reef annually from the years 1400 to 1800, the study found. That’s five times the median harvest in island nations worldwide today.
Dr. McClenachan and her co-author, John Kittinger, a researcher at the Center for Ocean Solutions in Monterey, Calif., drew on a variety of historical records and a method called catch reconstruction to estimate historical harvests in the Hawaiian Islands and the Florida Keys.
The Hawaiians used many techniques similar to those employed today, like temporary or permanent bans from fishing in certain areas, restrictions on certain species and gear, and catch limits. But they enforced the rules strictly; breaking them could mean corporal punishment or even death.
While the authors obviously don’t advocate such extremes, penalties in some areas could be stricter, the authors suggested, and enforcement could improve. In Hawaii today, “you get penalized much more harshly if you shoplift sunglasses from a store than if you take a bunch of fish that are the wrong size or kind,” Dr. Kittinger said in an interview.
Dirk Zeller, a fisheries scientist at the University of British Columbia who was not involved in the study, said that the conclusion made sense: Hawaiians were able to maintain such high levels because their fishing activities were so well managed and focused on a variety of different species, he said. They also left well enough alone, regularly outlawing fishing in spawning grounds and other areas to allow populations to regenerate, Dr. Zeller said.
The two places studied tell very different stories. As historians have documented, native Hawaiians employed a carefully controlled community-based system of regulations on fishing. Rules were passed down by oral tradition and recorded when missionaries introduced printing presses to the islands in the early 1800’s, Dr. Kittinger said.
In the Florida Keys, however, where intensive fishing didn’t take off until the mid-19th century, there have been fewer regulations and a repeating pattern of overfishing of one species for sale on global markets followed by a crash in that fish population and a switch to a new species. This cycle has severely depleted green turtles, sponges, sawfish and other creatures.
Now reefs in both places are overfished — “and there are less fish coming off the reef then back in the day,” Dr. Kittinger said.
Given that enforcement agencies are often underfinanced, he said, they might do better to devise a bottom-up approach. That is already happening in some areas, where officials have adopted co-management schemes with community groups that help draft rules and regulations.
Most productive reefs in long-ago Hawaii had community managers who knew a reef well and made rules unique to their own part of the ocean, Dr. Kittinger noted.
The researchers reconstructed historical harvest levels by calculating the amount of fish consumption per capita necessary to maintain estimated population levels in Hawaii over the last 700 years. Dr. Kittinger said the results were conservative because he and his colleague used the low end of anthropologists’ population estimates in their calculations.
While some may question the use of such historical data, Daniel Pauly a researcher at the University of British Columbia, said that such information was probably just as accurate as current harvest estimates. One can estimate the catch of an isolated society like Hawaii by using population rates, which can be inferred quite reliably by anthropologists, said Dr. Pauly, who was not involved in the study.
Dr. Zeller suggested that the study showed “that we must learn from the past to save the future.”
If more marine reserves were established and limits were firmly imposed on fishing, he said, the fishing industry could actually catch more fish while making less of an effort.
But the blame should not be assigned solely to regulatory agencies, Dr. Pauly said. “We moderns cannot stomach restrictions on fishing that are necessary to maintain the stocks,” he said.