Commercial fish farming hasn’t turned out to be an environmental cure-all, but solutions for sustainable aquaculture look surprisingly familiar.

How can a simple trip to the fish market turn into an exercise in science and morality? For eco-conscious consumers, it’s a serious catch-22: declining stocks of many wild fish populations can make farmed fish seem like a sensible alternative, but typical commercial aquaculture has its own trawler load of problems. So as the world’s demand for fish continues to increase while protecting wild stocks becomes even more critical, what makes an environmentally responsible (and financially viable) fish farm? Surprisingly, the answers may not lie in high-tech systems, but instead may be traditional techniques that have been around for centuries.

It doesn’t take a math whiz to see that current fishing trends won’t work for the future – in fact, they aren’t working right now. According to the United Nations Food and Agricultural Organization, three quarters of the world’s ocean fisheries are being pushed past their limits, including an estimated 25% that have been fished to the point of extinction. And as the world’s population grows, so will the demand for fish.

Nearly half of global fish consumption is already provided by aquaculture, but many current commercial farms simply aren’t sustainable. Crowded pens of fish along ocean shorelines make for convenient feeding and harvesting, but they bring a host of problems too. Pollution from waste and uneaten feed creates ecological dead zones; isolated populations are vulnerable to disease and genetic problems; and non-native fish that escape into surrounding waters can wreak havoc on local wildlife. Not to mention the bioaccumulation of nasty chemicals like PCBs that flow up the food chain, tainting feeder fish and ultimately ending up on the dinner plate.

But at least fish farming takes the pressure off wild fisheries, right? Not so fast. Farmed carnivorous fish like salmon, redfish and even shrimp require many times their own weight in fish feed, which has to be wild-caught in the ocean. So the net result of that farmed fish may actually represent a double whammy of environmental impact.

For The Future, Lessons From The Past

Strolling along certain stretches of Hawaii’s coast, you’ll notice huge, perfectly shaped ponds along the shorelines. These were fish farms developed 2,000 years ago, shortly after Hawaiians arrived in the islands. But there was nothing primitive about them - they were actually far more “advanced” than many of today’s commercial aquaculture operations. The ponds employed an ingenious system of gates to keep the water fresh as tides changed; they operated on a scale that wouldn’t overwhelm the local environment with waste; and maintenance was even more convenient than with today’s offshore enclosures. And perhaps most important, by raising a native, local species of fish (the prized Moi) these farms eliminated any risk to wild fish populations in the event of an escape.

This model of a native product produced and consumed locally is an especially valuable lesson for modern aquaculture. Of course, there was no alternative centuries ago in an age where the extent of globalization was a small expedition in an outrigger canoe, but it still makes sense today from an economic and sustainability standpoint. Where a farmed fish ultimately ends up is obviously part of the “green” equation, and raising locally consumed species makes good economic sense while reducing the energy footprint of the product.

For another, even older model of sustainable fish farming that endures today we can look to the Far East. Chinese aquaculture has been around since roughly 2000 BC, twice as long as the Hawaiian farms. Traditional Chinese operations are simple in principle, yet they can be vast in scale and remarkably advanced, like those that combine fish farms with agricultural lands to create a self-sufficient cycle that feeds the fish and in turn, cleans the water. But one of the biggest advantages of the traditional Chinese aquaculture approach is the use of herbivorous (or omnivorous) fish that thrive on a plant-based diet, since removing the need for wild-caught fish feed is a huge sustainability advantage for a fish farm. And many such species can thrive in either a saltwater or freshwater environment, making inland locations and maintenance far more flexible. Shellfish that require no food beyond the nutrients they naturally filter from the water are another amazingly sustainable seafood that the Chinese have cultivated for generations.

But will a modern consumer with western tastes go for exotic fish that can be raised in these traditional systems? Actually, many of the fish are already well-known options: trout, tilapia, and catfish are all popular seafood choices, and they can all thrive with a variety of water and food sources. Additionally, when it comes to introducing other lesser-known fish to consumers, local restaurants and seafood suppliers can have a huge influence - just because diners enjoy familiar fish like salmon doesn’t mean they wouldn’t try another locally supplied, sustainable alternative.

Even using historically successful models of sustainable fish farming, aquaculture alone won’t solve the world’s food supply issues. These techniques won’t work everywhere, and even the best fish farms still face important challenges like pollution control. But as the world’s appetite grows, sensible and sustainable aquaculture based on the lessons of the past can play a critical role in feeding a growing world.