The Promise and Perils of Fish Farming

Aquaculture, if done right, can put more seafood on more plates without harming the environment

An offshore farm in Oahu, Hawaii, raises threadfish, or moi, in a netpen (NOAA).

Fish farming at a glance

• Can help fulfill growing demand for fish
• Can bring benefits, such as jobs and food for developing countries 
• Needs strong policies to protect the environment

Aquaculture, or farming seafood, is not new: several thousand years ago citizens of ancient China raised common carp in ponds. Still, most fish that people ate was wild-caught.

But in recent decades, the world's appetite for fish has surged and aquaculture is booming. Today, what you eat is just as likely to have been raised on a farm as caught from the wild.

More fish from abroad

The seafood Americans eat largely comes from abroad. Unfortunately, many nations that supply us with farmed fish do not adequately regulate these operations.

To reap the benefits of aquaculture while safeguarding our ocean resources, both policymakers and fish farmers worldwide need to implement strong standards for aquaculture operations.

Fish farming involves a range of products and practices

Like agriculture, aquaculture is not just one industry. A large number of aquatic species, from seaweeds to scallops to salmon, are produced using a variety of systems in locations around the world. Each has its own particular benefits and risks.

For example, filter-feeders like mussels raised on ropes suspended in the ocean, a largely benign system, can help cleanse waters. Salmon raised in netpens (systems open to the water) allowing waste to pass through can pollute surrounding waters (more on the perils of salmon farming).

The promise of aquaculture: More fish on plates

Over the last 30 years, worldwide demand for seafood has ballooned, as the global population swells, affluence increases, and more people eat more fish. The U.N. Food and Agriculture Organization estimates that an additional 40 million tons of aquatic food will be required by 2030 — just to maintain current levels of consumption.

Americans love seafood. Only Japan and China surpass us in total seafood consumption. In 2006, Americans ate an average of 16.5 pounds per person, up four pounds since 1980, and the U.S. population continues to increase. Consumption is expected to keep rising, fed by a growing and aging population (older people generally consume more seafood) and public awareness of seafood as part of a healthy diet.

Sadly, the ocean's ability to produce fish is diminishing. With increasingly sophisticated fishing gear, humans' ability to catch fish has exceeded the ocean's capacity to produce fish. Many of America’s favorite kinds of seafood, from Atlantic cod to grouper and snapper, are severely depleted. (See Fisheries in Decline.)

Restoring wild fisheries can add to fish supplies, but experts agree that fish farming, or aquaculture, is the only way to greatly increase world seafood supplies.

Other benefits: Food for world's poor and jobs

Aquaculture can bring benefits. The fisheries sector, including fish farming, helps alleviate poverty in many parts of the world. Over one billion people rely on fish as a main source of protein, many of them in developing countries. The dominant fish farmed worldwide is carp, which is chiefly produced in Asian countries for domestic consumption.

Other seafood items such as salmon and shrimp are produced for sale mostly in international markets: Global fisheries exports now earn more revenue than any other traded food commodity, including rice, cocoa or coffee. Aquaculture development provides jobs in production, processing and sales.

The perils of aquaculture

Unfortunately, there are cautionary tales of fish farms that do economic and ecological damage. For example, in Thailand, Ecuador and many other tropical nations, coastal forests of mangroves were cut down in the past and replaced with shrimp farms.

These degraded the water and many eventually closed or relocated, leaving local peoples without the farm or the mangroves. (Mangrove forests provide critical habitat for commercially-important fish and shrimp, filter water and buffer the coastline against storm waves.)

Main ecological problems and how to avoid them

The chief harmful effects of fish farming on the environment are listed below. A number of technologies and practices can prevent or mitigate such problems.

Problem: Polluting waters. Some production systems allow uneaten food, fish waste and drugs and chemicals to pass into surrounding waters, where they can harm ecosystems and impair water quality.

Better ways: 

• Use closed recirculating systems (used for some finfish production, such as Arctic char) to better control and treat effluents, or wastewater.
• Grow more than one species. A holistic approach uses seaweeds and "filter-feeders" such as mussels near fish farms to remove microorganisms and nutrients, thus improving water quality.
• Minimize use of antibiotics and anti-parasite drugs with an array of measures to keep fish healthy, including vaccinating fish and stocking ocean fish pens with small fish that naturally feed on parasites.

Problem: Depleting wild fish stocks. Farming predatory fish like salmon can use huge amounts of small, oily wild fish like anchovies, menhaden, mackerel and herring. These small forage fish are made into fishmeal and fish oil for feed, and more pounds of wild fish are consumed than the farm produces.

Overexploitation of these small fish can deprive larger fish and other sea life of food. Over the past two decades, close to one third of the current annual catch has been used for animal feed.

Better ways:  

• Farm vegetarian or semi-vegetarian fish such as tilapia and catfish or filter-feeders like mussels or clams.
• Feed predatory fish a semi-vegetarian diet supplemented with byproducts of fish destined for human consumption.

Problem: Introducing risks to wild fish species. Escaped farmed fish can pose serious threats to wild fish populations by competing with them for food and habitat and transmitting disease and parasites.

Better ways: 

• Farm species native to the region to reduce the potential harm from introducing a new fish species.
• Use closed systems like tanks, rather than "leaky" netpens or cages, to prevent escapes.
• Mark fish and require public reporting of escapes, to identify culpable suppliers.

Problem: Endangering sea animals. To keep them from feeding on captive fish, wildlife such as seals, sea lions and birds are often harassed with firecrackers or loud underwater speakers that can cause disorientation, pain or hearing loss. Marine mammals and bird predators are sometimes even shot.

Better ways:  

• Site farms far from places where marine mammals live or hunt, or birds congregate.  
• Use tight nets to prevent access by predators to ponds, tanks, and net cages.

Farming of the future: Polluting feedlots? 

Historically, most marine (or salt water) farming in the U.S. has been done nearshore (generally up to 3 miles out). But the dramatic increase in coastal development in recent years means that clean water and suitable sites are at a premium. Fish farming requires dedicated space for pens, cages or tanks, competing with traditional uses like boating and recreational fishing.

A lack of locations to site new farms has in part stimulated more seafood imports. More than 40 percent of seafood from abroad is farmed (primarily shrimp, salmon, catfish and tilapia). But recent reports of farmed fish and shellfish from China tainted with potentially harmful chemicals may prompt American consumers to look increasingly for U.S.-produced fish.

To expand the supply of domestic fish and lower the seafood trade deficit, the U.S. Commerce Department has called for expanding the $1 billion aquaculture industry fivefold by 2025. At the request of the National Oceanic and Atmospheric Administration (NOAA), several members of Congress have introduced legislation to spur fish farming in the deep ocean, primarily in federal waters (generally 3-200 miles out), beyond the reach of state laws.

Without strong standards, large-scale industrialization of fish farming in deep offshore waters would be analogous to animal feedlots on land, bringing similar problems with waste and environmental degradation. Unfortunately, NOAA to date has not incorporated adequate environmental protections into the agency's proposed legislation.

What Environmental Defense is doing

Environmental Defense has long been at the forefront of efforts to meet fish farming's ecological challenges and develop strong national policies to protect the environment.

Working for strong national standards in offshore waters. Our expert Dr. Becky Goldburg served on the Marine Aquaculture Task Force, convened by the Woods Hole Oceanographic Institute to recommend standards and practices for U.S. marine aquaculture for protecting the health of marine ecosystems. (Read 2005 news release.)
 
Developing sound national organic standards for farmed fish. Robust growth of farmed fish, coupled with environmental and health concerns, have fueled interest in organic aquaculture. Although some fish labeled organic are sold in the U.S., they are certified by a myriad of private European agencies with varying standards. The only state prohibiting sales of "organically" labeled fish until U.S. standards are in place is California.

Dr. Goldburg serves on a working group created by USDA's National Organic Standards Board to develop strong standards.

Showing that seafood can be farmed in a profitable, eco-friendly way. Ocean-friendly seafood can provide many opportunities to improve the growth and longevity of seafood businesses. Our experts work with suppliers and retailers on purchasing standards for farmed fish, with some notable successes. We have partnered with Wegmans Food Markets, one of the country’s most successful and innovative grocers, to develop a purchasing policy for sustainably produced farmed shrimp.

In the past, we worked with Wegmans and Bon Appétit Management, a leading on-site restaurant company, to help them develop and adopt new purchasing policies for farmed salmon. The policies, which include stringent health and environmental standards, serve as model for others in the industry.

Promoting ocean-friendly seafood to consumers. Environmental Defense's staff of experts on fish, aquaculture and health have compiled the latest research on more than 180 different kinds of popular seafood for our Best Choices list.  We partnered with the Monterey Bay Aquarium to provide environmental and health advice on our web site and Pocket Seafood Selector based on the best available science so consumers can make ocean-friendly seafood choices that are safe to eat.

Posted: 01-Jan-1900; Updated: 30-Oct-2007