Is Something Fishy In Aquaculture?

By Nancy K. Crevier

Fish consumption has become synonymous with good health in recent years. Low in calories, saturated fats and cholesterol, fish is also an excellent source of protein, vitamins and minerals. Headlining the good news has been salmon, one of several species high in omega-3 fatty acids, which may decrease the risk of coronary artery disease and help lower blood pressure.

A three-ounce serving of salmon provides half of the weekly dietary allowance of omega-3 oils. Two servings of fish every week, each about the size of a deck of cards, offer protection to those at risk of heart disease, according to the American Heart Association.

But as with any commodity popularized by media and word of mouth, it seems that salmon has fallen victim to its own success. As consumers eat ever-increasing amounts of salmon, the fishing industry has struggled to keep up with demand.

One of the solutions to keep American dinner plates full of the pink-fleshed fish has been the advent of aquaculture, or farmed fish. Aquaculture is the controlled production of aquatic plants and animals. It has been practiced in China for more than 2,000 years, but it is only since the 1980s that it has becoming a thriving industry in other countries.

Initially, farming fish, particularly the high-profile salmon, seemed the answer to providing sufficient quantities of fish for health-conscious Americans. More fish could be produced at lower prices on a local level. Farmed fish would be healthier for consumers, as polluted oceans and waterways threatened the quality of the fish that call those waters home.

As aquaculture has thrived, more fish has been produced at lower prices. Prices for farmed salmon are competitive with the prices for wild-caught salmon, and provide a source of salmon when wild-caught salmon is out of season. Senior biologist and certified fisheries professional Bill Manci, who is with Fisheries Technology Associates, Inc, stated in a September ‘05 report that by 2030, more than half of all fisheries products consumed worldwide will be from aquaculture sources.

But behind the good news hovers the bad: salmon and other fish produced via aquaculture may not be as healthful as was once hoped. News reports and scientific studies vary widely in opinions of the safety of eating farmed salmon vs wild caught. On one side are the proponents of aquaculture and on the other are the environmentalist groups. Health experts support aspects of both sides, adding to confusion for the average person.

Studies performed in Canada and the United States have shown elevated levels of carcinogenic contaminants in farmed fish. These contaminants include not only the much publicized mercury that taints nearly every species of wild fish, but polychlorinated biphenyl (PCB), which is a synthetic, organic chemical, and various dietary additives, pesticides, antibiotics and fungicides.

The toxins, it appears, are introduced through farming practices and via the feed used to grow the salmon in captivity. Farm raised fish are fed pellets rich in fish oils. Because PCBs are stored in fat, the oil-rich feed pellets harbor concentrated amounts of PCBs and are a highly suspected source of PCBs in farmed fish. A controlled diet and an environment that restricts natural movement mean that farmed salmon usually are fattier than those caught in the wild. More fat means more potential for elevated levels of PCBs.

PCBs occur in many other foods that are part of the daily diet. Meat, milk and other dairy products can contain far higher percentages of contaminants than farmed or wild caught fish. And because most Americans eat larger portions of these foods more frequently, toxins in the diet are more likely to come from these than from the consumption of fish.

A 2003 Science News report notes that citizens of industrialized nations, such as the United States, devour 80 kg (about 176 pounds) of meat each year per person. Frozen Food Digest in 2002 reported only two pounds of salmon per person a year is consumed.

How Much PCB?

How much PCB is allowable? The current Federal Drug Administration limits for PCBs in fish are 2 ppm (parts per million.) These standards, however, have not been updated since 1984. The stricter, 1999 Environmental Protection Agency recommendations are that no more than 8 ounces a month of fish with PCB levels of between .024 and .048 ppm should be eaten. The average level of PCBs in salmon is .027 ppm.

Three years ago, the Environmental Working Group reported that farmed salmon sold in the United States contained 16 times the amount of PCBs found in wild caught salmon. In 2004, Science journal reported ten times the amounts of toxins in farmed salmon as that of wild caught salmon.

The toxins come not just from the feed, however. Overcrowded fish factories create environments that require the use of pesticides to combat rampant spread of a parasitic infection known as “sea lice.” Antibiotics and other medications are fed to fish in captivity to prevent the spread of disease and in some cases, according to People for the Ethical Treatment of Animals (PETA), drugs and hormones are administered to accelerate growth.

Not only the fish in captivity are affected by aquaculture, says PETA. The unhealthy environments in which ocean-farmed fish are raised contribute to pollution of the oceans due to the collection of fish waste on the ocean floor, and despite all efforts, farmed fish do make their way into the wild, bringing with them disease and in-breeding that affects the wild population.

It would seem that the high fat, farmed fish would be higher in heart-healthy omega-3 oils than their lean, wild counterparts. But at websites such as whfoods.com, information provided suggests that farmed fish are significantly lower in omega-3s than their wild counterparts, perhaps as much as two to three times less. In an effort to decrease the amounts of PCBs stored in fatty farmed fish, feeds are being developed with less fishmeal in them and more plant foods. Unfortunately, the salmon raised on the plant food pellets end up lower in omega-3 fatty acids. Wild salmon, which eat no plant foods at all in their natural habitat, generally contain higher levels of omega-3 fats.

Information from the Mayo Clinic in Rochester, Minn., though, states that the omega-3 levels of farm-raised fish are comparable to that of wild caught.

It is a conundrum for consumers.

Mr Manci feels that because modern aquaculture has taken many steps to rectify issues of farm-raised fish, such as the use of benign substances to stimulate fish immune systems, rather than overuse of antibiotics, and the implementation of late-stage feeding methods to concentrate omega-3 fats in the tissue at harvest while overall decreasing the amount of omega-3 enriched pellets, it will provide a healthy, affordable alternative to the overfished wild caught fish industry. He believes that totally eliminating fish from the diet because of perceived dangers could lead to health consequences that outweigh the alternatives.

Benefits Exceed Risks

Dr Julie Conner of Healthy Weighs in Brookfield is a registered dietician and nutritionist who has been in practice for 23 years. “I think that regardless of what you eat, you can find some controversy about it in the nutrition field,” she said. Even so, she believes that the benefits of eating fish exceed the risks.

A big advocate of the omega fatty acid rich salmon, she added, “Wild salmon is definitely my first choice. The problem I would have with addressing farmed vs wild salmon is that when you purchase salmon in a regular grocery store, where it comes from is usually not listed on the label.” This can be confusing and frustrating to the consumer, she said, if the source of the salmon is not listed.

Toxins in wild salmon can vary based on where it is caught. Wild salmon caught in the vicinity of fish farms have shown increased levels of mercury in their flesh, according to an April 2006 article from the American Chemical Society.

Further confusing the issue, salmon marketed as “organic” has shown up in supermarket fish cases across the country, even though organic standards for the seafood industry have not yet been set by the United States Department of Agriculture.

What is available from certain purveyors is salmon that is raised without the use of antibiotics, hormones, coloring agents, or pesticides. This salmon is fed a certified organic fishmeal and grain feed. Opponents scoff that environmental issues are still not resolved by so-called organic farming practices and consumers pay a premium for the more naturally raised salmon, putting it out of the reach of the average shopper. If salmon is not affordable, it is not purchased. If it is not purchased and eaten, then any benefits a person would obtain from this superior source of omega-3 fatty acids is not derived.

The facts remain that all salmon is lower in saturated fats than red meat. All salmon are an excellent source of omega-3 fatty acids, too. As with so many other choices in the modern world, a moderate approach to fish consumption is key to reaping the unchallenged benefits of this food. It is a consumer’s feelings toward supporting an aquaculture industry that by many accounts has a way to go in the ethical treatment of and the potentially hazardous practices of raising fish in captivity that may hold sway when faced with the decision at the fish counter: farmed or wild?