published in the Global Aquaculture Advocate, December 1999, vol. 2, #6

Is it environmentally responsible to buy and sell farmed seafood? This is the question increasingly being asked of consumers and food retailers alike.

Consumers do need to know more about the seafood products they buy and the impact of their purchases. Unfortunately, only one side of the story is being told. As aquaculturists, often more focused on fish farming than public relations, we need to respond clearly with the facts.

Let's start with the most important fact: Aquaculture is the only sustainable mechanism to increase seafood production.

World Food Needs

The world's population now exceeds 6 billion and is still growing, according to a recent announcement by the United Nations. To feed humanity for the next 40 years, we will have to produce more food than all the food produced since the beginning of time. How can we do that?

From the beginning, mankind turned to the seas for food, and the seas were plentiful. In the past 20 years, however, the oceans have reached their limit. World landings of edible seafood gradually have leveled off around 60 million metric tons per year. Additional fishing pressure only depletes wild stocks.

The solution to this crisis is farming - the same solution mankind developed ages ago when wild game became scarce. Aquaculture, the farming of aquatic organisms, relieves pressure on wild fishery stocks and raises food production in a sustainable way. It is a young industry, with a bright future.

In a recent New York Times interview, management guru Peter Drucker predicted that one of the new century's most exciting industries was not the Internet, but fish farming. Yet, just as our ancestors could scarcely imagine that the vast oceans would one day be fished to their limit, our own generation struggles to grasp the tremendous potential of aquaculture.

Is Aquaculture Sustainable?

The U.N. World Commission on Environment and Development defines sustainable development as: meeting the needs of the present without compromising the ability of future generations to meet their needs. However, not all environmentalists agree. Randal O’Toole of the Thoreau Institute, an environmental think tank, divides the modern-day environmental movement into two groups: preservationists and conservationists.

In the preservationists' view, nature knows best and nature should be preserved at any cost. For them, sustainability means "no impact." In this context, neither aquaculture nor any other system of food production has much growing room.

The question for preservationists is simple: how can 6 billion people survive on this planet with "no impact" from development? Humanity's need to breathe, eat, create waste, and shelter itself has a profound impact on the earth's ecosystem. We can seek to attenuate the negative aspects of that impact as much as possible, but there will always be some impact.

Conservationists are more realistic about sustainability. Their goal is to maintain ecosystems through collaborative management by public and private stakeholders at the local level.

Clearly, aquaculturists are also conservationists. In most areas of the world, water rights arc publicly-held, and access to space for aquaculture requires that farmers engage in a permitting process with local government organizations. For instance, in the state of Maine, USA, no salmon farm lease site is granted unless the request is approved by four state government agencies, which invite review by all stakeholders.

Watchdogs and Soundbites

Regardless of their preservationist or conservationist leanings, environmental groups make an important contribution by alerting the public to hazards and risks. However, as environmental groups proliferate and compete with each other to capture public attention and funding, there is a tendency to reduce facts to quick ideas and cliches, known in the mass media trade as "soundbites." Reality does not lend itself well to soundbites, but exaggeration and emotion do.

In a recent survey to quantify cancer risks, researchers sent a questionnaire to 400 cancer experts, each of whom had published an average of 50 scientific papers on cancer. The experts were asked to rank a variety of cancer risks such as sunlight, tobacco, alar, DDT, asbestos, etc.

The same questionnaire was sent to 100 leading environmental groups. Results showed that environmentalists greatly magnified many of the risks as compared to cancer experts. The challenge of the seafood industry is to resist the temptation to swallow soundbites, and to insist on a review of the facts.

The Aububon Seafood Card

Recently, the National Audubon Society released a packet of educational materials from its Living Oceans Program under Dr. Carl Safina, author of Song for the Blue Ocean. As part of the package, Audubon distributes a small, perforated card to be used at restaurants and grocery stores (see illustration below). Along a sliding scale from best to worst, the card rates 34 of the world's major seafood groups. Farmed shrimp and salmon--ranked in the worst category-are flagged by a "do not eat" symbol. The only explanation offered for Dr. Safina's sweeping rankings is a 2-page summary, "The Audubon Guide to Seafood."

Audubon's Case against Shrimp

The Audubon Guide refers to farmed shrimp in just one soundbite:

"shrimp farms pollute and destroy habitat-so much so that the Indian government recently ordered more than 100 farms closed." Let's take a critical look at the each of these assertions.

"Shrimp Farms Pollute"

Pollution to the consumer conjures up visions of smokestacks, toxic waste, and health hazards. In the case of shrimp farms, the discharge from ponds consists of natural algae and organic matter. It is neither toxic nor illegal.

Over the last 10 years, shrimp farmers have halved the quantity of water discharged per kilogram of shrimp produced, and they are continually testing new technology to further reduce discharges. So the assertion about pollution is exaggerated and out of date.

"Shrimp Farms... Destroy Habitat"

This statement refers to the misguided assumption that shrimp farming threatens mangrove swamps. Indeed, most shrimp farms are located in the tropics and some are near coastlines fringed with mangrove swamps.

Early shrimp farmers were actually encouraged by governments to tap mangrove areas as "swampland suitable for development." However, shrimp farmers soon learned that the poor drainage and acidic soils of mangrove swamps were poorly suited for pond construction.

It is far better to build farms on higher ground, and leave mangrove areas intact to help recycle discharge nutrients-and protect farms from erosion and storm surges. Shrimp farmers recognize the value of mangroves and are leading mangrove conservationists. In Honduras, high altitude imagery shows that the area of man-groves in the vicinity of shrimp farms actually has increased in the last 10 years.

"The Indian Government Recently Ordered More than 100 Farms Closed"

This assertion is misleading. In 1995, shortly after shrimp farming began in India, a shrimp disease passed through many farms, resulting in financial loss and bankruptcy for some. This led to accusations of nonsustainability and unnecessary social disruption of coastal communities. A legal battle culminated in a 1996 Indian Supreme Court ruling to close all shrimp farms within 500 m of the high-tide line. However, the decision was later stayed before it could take effect, saving hundreds of thousands of small farmers from ruin.

The Indian government now proposes to introduce an aquaculture bill with environmental safeguards for sustainable development. Meanwhile, Indian shrimp farmers are learning to manage disease, and their production has increased to some 70,000 metric tons per year.

Accusations Against Salmon

The Audubon Guide to Seafood refers to farmed salmon in one sound-bite: "salmon farming pollutes, displaces wild fish, and prompts the shooting of predatory seals near farms." Let’s consider each assertion.

"Salmon Farming Pollutes"

This statement is a distortion of the truth. Most salmon are raised in floating net pens anchored in cold, deep water along the protected coastlines of Norway, Chile, Scotland, Japan, U.S., and Canada. Regulatory frameworks are well established in these regions, and siting of salmon farms is subject to strong oversight based on sophisticated water quality models. Regulators often send divers to the ocean floor under fish pens to take samples and monitor the health of the ecosystem. Lease applications are not renewed for sites that do not meet strict environmental standards.

It is important to put waste discharge in context with the amount of tidal flushing. For example, a typical salmon farm with 18 cages and 500,000 salmon produces a total of 147 pounds (dry weight) of fecal matter per tide change of 864 million gallons of water. In an everyday context, this amounts to the equivalent of 2 tablespoons in 24 backyard swimming pools.

In British Columbia, Aquametrix Research analyzed data from three provincial Canadian government studies reviewing the environmental impact of salmon farming waste in B.C. The conclusions: "the actual loss of wastes to the environment by today’s industry is approximately one-third of what it was in the late 1980s. This in spite of the fact that production levels at these sites have increased approximately three times." A study by the Nature Conservancy in Maine showed that in Cobscook Bay, which hosts the state’s greatest concentration of salmon farms, less than 10 percent of organic loading could be attributed to salmon farming.

The degree of pollution caused by the use of antibiotics also creates heated debate. Using the worldwide industry average as an example, no more than 2 percent of feed given to farmed salmon is medicated with antibiotics, which are used to minimize the impact of naturally occurring bacterial infections. Why is the number so low?

In the case of Atlantic Salmon of Maine, all egg and sperm in their hatcheries are tested for disease, thus ensuring that baby salmon are disease-free. As extra insurance, each baby salmon is vaccinated, much like a child is immunized, before it is placed in an ocean pen. Thanks to this preventive step, in 1998 Atlantic Salmon of Maine had an infinitesimally small amount (0.00183%) of feed medicated, which by law is done through veterinarian prescription.

"Salmon Farming Displaces Wild Salmon"

This assertion is unfounded. The question of farmed salmon escapees mating with or weakening wild salmon is greatly contested. DNA testing of wild stocks is underway in several production areas to see if any contain markings that suggest crossbreeding. So far, geneticists disagree on whether testing shows a crossbreeding link. In fact, by keeping a variety of salmon genes thriving through salmon farming, a broad gene pool is being preserved for future generations.

With the advent of vaccinations and disease-free brood stock, the argument that salmon pens spawn diseases that kill wild salmon is difficult to substantiate. It is known that for 100 years before salmon farming started in Maine, the federal government stocked millions of salmon into the rivers of Maine and never once did a self-sustaining run ever materialize. Some believe that to discover what has happened to wild salmon in Maine, the 100 years of federal government hatchery-restocking work needs to be as closely scrutinized as the work of the newly-arrived aquaculture industry.

"Salmon Farming Prompts the Shooting of Predatory Seals near Farms

This assertion is not supported by facts. A 1998 study by Drs. Gilbert and Guldager at the University of Maine's Department of Wildlife Ecology found that in the region of the state where salmon farming is located, harbor seal population growth is more robust than in any other part of the state. In fact, the researchers concluded that the Downeast region’s annual 17.6 percent population growth rate in the last 17 years (about the time when salmon farming began in Maine) was a strong signal of the health of the seal pup populations near the salmon farms.

Other studies have shown that populations of lobsters, mussels, and various shellfish as well as bald eagles and osprey also flourish near Maine's salmon farms.


Aquaculturists should recognize the need of seafood buyers and consumers to be better informed about the impact of their purchases. From an environmental perspective, aquaculture dovetails with conservationist goals more than many standard agricultural practices do.

As environmental groups try to simplify their arguments for mass media, they tend to exaggerate the facts and appeal to emotion. The National Audubon Society has asserted that it is not environmentally responsible to consume farmed shrimp or farmed salmon. However, their soundbite judgments are not supported by the facts. The truth is that aquaculture is a young, rapidly-growing industry with a promising future as the only sustainable means of increasing seafood supply to meet world food needs.

For more information about this reprint or aquaculture, contact P0. Box 7488, Portland, ME 04112-7488