View Cart

Catch-22: Can We Harvest the Health Benefits of Seafood Without Destroying the Oceans?

Saturday, 15 January 2000 0:44 By Erik L. Goldman | Editor in Chief - Vol. 7, No. 4. , 2006

Wild Bluefin Tuna (Thunnus thynnus) behind the net walls of a “tuna ranch” in the Mediterranean Sea. Fishermen attract schools of tuna to the nets with large volumes of smaller bait fish. Once the tuna are corralled, tugboats tow the giant pens closer to shore. Increasing demand for ocean fish has led to overfishing and widespread destruction of marine habitats. Without careful fisheries management and greater consumer eco-consciousness, many ocean ecosystems could collapse. Photo: Greenpeace/Gavin Newman.

If you think of the oceans as the circulatory system of the planet, with the various types of fish as blood cells, then you could say that Mother Earth has a bad case of pernicious anemia, with increasingly abnormal blood chemistry, and very high risk for fatal arrhythmia. The imperiled health of the oceans is no longer just a matter for eco-activists; it is a public health issue.

Increasing demand for fish, omega-3 rich fish oils, and marine biomass for animal feed is a major stressor on the oceans, already compromised by industrial pollution, rising water temperatures, melting polar ice, changing aquatic pH, demineralization of coral reefs, and disturbing shifts in thermal currents.

The medical community’s formal advocacy of fish—strongly articulated in two recent publications, one a white paper from the Institute of Medicine, and the other, a metanalysis from Harvard researchers in the Journal of the American Medical Association—will, no doubt, stoke demand, putting further pressure on already fragile marine ecosystems.

These new reports may alleviate public concern about risks of methyl mercury and other environmental toxins in ocean fish. Both affirm the safety and health value of fish, with the Harvard authors going so far as recommending regular fish consumption to prevent heart disease. While acknowledging heavy metal pollution as a problem, they claim people can largely avoid it by limiting consumption of large fish like tuna, swordfish, and shark (see Naturopathic Perspective from this issue for Dr. Traub’s more detailed analysis of the two papers).

That’s all well and good. But the IOM report and the Harvard paper largely overlook the bigger problem: the oceans are in critical condition, with some marine ecosystems on the verge of total collapse. By increasing our fish consumption, are we buying short-term personal health gains at the price of long-term eco-catastrophe? Put another way, can we have our fish and eat them too?

The short answer to that complex question is “Yes,” say many marine ecologists. But only if we implement serious changes in global fisheries management, while raising consumer consciousness. Massive fishing enterprises must embrace a conservation ethic; consumers need to think ecologically.

Hitting Bottom

“Fisheries worldwide are in deep trouble,” said Becky Goldburg, PhD, a senior marine scientist at Environmental Defense, a major conservation group. “The UN estimates that about three-quarters of the planet’s fish stocks are now fished to their maximum limits or are already exhausted. We’re seeing a 90% decline in overall biomass of large predatory fish like cod, haddock and tuna.”

The annual worldwide commercial fishing haul peaked in the late 1990s at roughly 96 million tons. The numbers have been declining at roughly 3 percent per year since then, despite higher demand and more effective fishing technologies. Those are conservative estimates; actual declines may be bigger.

Fishing in much of the world is entirely unregulated. “Even in US waters, where we have relatively good fisheries management by world standards, one third of our fish stocks are being over-fished,” said Dr. Goldburg. Recent US Dept. of Commerce figures indicate 28% of US fish stocks are officially “overfished,” with another 19% “subject to overfishing,” meaning that it is only a matter of time.

In unregulated international waters, attrition is much higher. “People are taking fish at rates that cannot be sustained,” Dr. Goldburg told Holistic Primary Care.

Just weeks after the IOM and Harvard reports, Science published an alarming analysis by Boris Worm at the University of Halifax, predicting that if current trends continue, seafood stocks around the world will collapse completely by mid-century. Dr. Worm’s team analyzed nearly 500 million fisheries records in the University of British Columbia’s Sea Around Us Project database. They found 29% of seafood stocks that were plentiful in the 1950s were already exhausted by 2003 (Worm B, et al. Science. 2006; 314: 787–790).

Critics, like Steve Murakowski, of the National Oceanographic and Atmospheric Administration’s (NOAA) fisheries service, debate the validity of Worm’s methodology, the main objection being that the study defined “exhaustion” as a drop of 10% or more below historic maximal yields—a questionably high threshold. But no one disputes Worm’s main point: the waters are being dangerously overfished.

Most of the global catch is going to the US, Europe and Japan. “We’re vacuuming up huge quantities from all over the world. Roughly 80% of the fish consumed in the US is imported,” she said. That sucking sound will only intensify with rising affluence in China and other Asian countries.

By-Catch: Unnecessary Slaughter & Waste

Commercial fishing is grossly inefficient. “By-catch,” is the industry’s term for unwanted marine life of little commercial value that happens to get swept up with desired species. By-catch figures are staggering. As much as 88 billion pounds of sea creatures are unnecessarily killed each year. Unwanted species, including turtles, seals, porpoises, sharks, seabirds, and a host of unmarketable fish, comprise up to 25% of the global fishing haul.

Much by-catch can be prevented with changes in fishing techniques, as has been demonstrated in well-managed fisheries in the Pacific Northwest. But world wide, regulations are lax and enforcement is nil.

According to Joar Opheim, founder of Nordic Naturals, one of the nation’s leading fish oil brands, the fishing industry is often extremely wasteful, even in well-managed waters. “We really need to look at how we are using the fish we are bringing up,” he said in an interview. His company recently negotiated a special arrangement with Norwegian Arctic cod fishermen to obtain the oil-rich livers—at a premium price—which the fishermen had been tossing into the water.

“The factory fishing boats are only interested in the fillets, and they don’t want to take up space, so they were throwing all the guts including the livers—which are an incredible resource—overboard.” Mr. Opheim stressed that unlike Atlantic cod, Rock cod and other species that have been fished to near extinction worldwide, Arctic cod stocks in Scandinavian waters are very clean and closely managed. Until recently, though, one of their most valuable assets—the oily livers—was being wasted.

The Catch-Sharing Solution

Dr. Goldburg and others concerned with marine ecology believe a key solution is to base fisheries management on catch-sharing systems in which fishermen have a direct stake in protecting stocks. Catch-sharing means allocation of defined shares of a year’s allowable catch for big market species.

“Right now, in many parts of the world the only rational thing for fishermen to do is to take as many fish as they can, because they know that if they don’t someone else will.” Dr. Goldburg said. Catch-sharing reverses the incentives. If each fishing company can only take a defined cut of a year’s catch, fishermen are motivated to conserve fish—by not killing off juvenile fish, for example—so that over time, total permitted catch size will increase. Since catch-shares themselves can be sold, the value of a share increases with the size of the allowable catch.

According to Mr. Opheim, this is the norm in Norway, where fishing is a major economic sector. “The government monitors the waters very closely to identify how many of each important fish there are. They determine overall quotas, which are divided down to the level of individual boats. You can only take certain numbers, and violations are heavily fined. It’s been that way for 30 years, and it seems like it’s working.”

It seems to work well in Alaska, too. “Management of fish stocks here is completely separate from the market. Only very finite amounts of each type of fish can be caught, depending on the size of the runs,” explained Randy Hartnell, a longtime Alaska salmon fisherman, and president of Vital Choice Seafood, a company he founded with other eco-conscious Alaska fishermen.

Variable run sizes can result in significant price fluctuations. For example, the price of wild Alaskan King salmon is up 43% this year. “Demand is up, but the runs have been steady or slightly low, and we’re only permitted to take a fixed amount. Here in Alaska, we’ve learned that the fish and the oceans are so valuable, and we recognize the need to protect them.”

Catch-sharing is still controversial, and certainly not the norm. First of all, it requires strong government oversight, careful monitoring of fish stocks by independent agencies, honest estimates of catch limits, and most importantly, monitoring of each boat’s “take,” and punishment of violations.

Initial allocation of shares must also be done carefully. “There can be winners and losers,” said Dr. Goldburg. If share-trading rules are too lax, large companies can end up aggregating them, leading to monopolies, exploitation of fishermen, and wreckless handling of fish stocks. Fortunately, catch-sharing at least in principle, has support from fisherman and conservationists alike; it is unlike forest protection plans, where eco-activist “outsiders” are at odds with local loggers.

Is Fish Really So Healthy?

Catch-sharing and other marine protection measures would be largely unnecessary if people ate less fish, rather than more, according to the Physicians’ Committee for Responsible Medicine (PCRM), an organization representing healthcare practitioners advocating vegetarian and vegan diets.

Taking a position in direct opposition to the new IOM and Harvard reports, PCRM claims seafood is hardly the health cornucopia it is made out to be, but rather a risky bet. “The problems go beyond mercury and other contaminants,” said Hope Ferdowsian, MD, MPH, in a PCRM press release. “Fish are surprisingly high in cholesterol and saturated fat … which accounts for 15 to 30% of fish fat. Ounce for ounce, shrimp and lobster are much higher in cholesterol than steak.”

PCRM concedes that many ocean fish are high in omega-3 fatty acids, which have cardioprotective properties, but argues that from a caloric viewpoint, these “good fats” are just as likely to promote weight gain as bad fats. Dr. Ferdowsian also pointed out that 25% of all fat in Chinook salmon or Swordfish, both valued for high omega-3 content, is saturated fat.

The most nutritious omega-3 sources, says PCRM, are plant-based, like leafy greens, legumes, soy, walnuts, and flax. That’s true, in theory, but pretty untenable in practice. Flax and other plant sources provide omega-3s, but only as alpha-linolenic acid, which must be converted to DHA and EPA, the key omega-3s, through inefficient metabolic processes. You’ll need to eat an awful lot of legumes and flax to equal the omega-3’s of a big sushi dinner.

There are many virtues to a vegetarian/vegan diet, but high omega-3 content is not one of them. If the objective is to raise omega-3 levels significantly—and many health experts believe we should if we want to decelerate heart disease, diabetes, arthritis, inflammatory disorders, and cognitive/behavioral problems—fish and fish oils are going to stay on the menu.

Serious O-3 Deficiencies

According to a recent white paper by the Council for Responsible Nutrition, 40% or more of US adults are frankly deficient in omega-3s. Average fish oil intake in the US is less than 5% of what it is in a fish-loving, seafaring nation like Norway, said Mr. Opheim. Unfortunately, we’ve got the cardiovascular and inflammatory disease incidence stats to show for it.

“The benefits [of omega-3s] are really undervalued in the US, but they are really dramatic,” he told Holistic Primary Care, his point recently bolstered by an article in the Wall Street Journal decrying American cardiology’s long resistance to fish oils in managing myocardial infarction. US doctors are about 10 years behind their European colleagues, who routinely use fish oil in cardiovascular care.

The fish oil industry, though growing fast, is thankfully leaving a relatively light mark on ocean ecosystems. According to Ian Lucas, of Ocean Nutrition Canada, supplier of the Meg-3 brand of fish oils for the supplement and functional food industry, reputable fish oil companies are obtaining their oils primarily from small fish like sardines and anchovies that are plentiful, have short reproductive cycles, and can be sustainably managed. Fish oil for nutritional supplements represents no more than 2%–3% of the total global fishing industry.

Aquaculture Clash

The relentless demand for seafood has spurred rapid growth in fish- farming. But if you think aquaculture will solve the ocean’s woes, guess again.

“Like any agriculture, fish farming is complicated. Roughly 200 species of fish and mollusks are farmed worldwide. Some, like mussels, oysters, catfish, and striped bass can be farmed in an environmentally reasonable way. Others like shrimp and salmon are huge problems,” said ED’s Dr. Goldburg. That’s unfortunate, given that Americans’ No. 1 seafood choice is shrimp, and No. 3 is salmon (canned tuna holds the No. 2 position).

Many of the world’s fish farms are in Southeast Asia or South America, where regulation is pretty lax. Sprawling aquaculture operations destroy coastal marshlands and mangrove forests, nurseries for indigenous wild fish species. Further, shrimp and salmon farms, especially in Asia, use huge amounts of fluoroquinolone antibiotics to protect fish from infections. This amplifies selective pressures favoring resistant pathogens.

Fish farms, like their land-based counterparts, are also big polluters. Essentially, they’re underwater feed lots, generating tons of filth, which diffuses out and fouls neighboring ecosystems.

Farmed fish frequently escape their pens, often to negative effect for local fish. Escapees may carry parasites foreign to their host waters. In the case of salmon, escapees inter-breed with wild species, resulting in hybrids that don’t reproduce well in the wild. This can be damaging in areas where wild salmon are already having a hard time. Escaped Atlantic salmon are now found all over the Pacific Northwest, where they compete with fragile Pacific species.

Fishing to Feed the Fish

By far the biggest eco-threat posed by aquaculture is that it swallows up huge quantities of wild marine biomass. Farmed salmon have to eat, and their salmon chow is primarily … guess what? Ground up fish. Depending on whose numbers you read, the feed industry sucks up between one-quarter to one-third of all marine biomass caught worldwide.

“The fish feed industry is enormous. It’s hundreds of billions of dollars each year. People have no idea!” said Nordic Naturals’ Mr. Opheim. “Fish farming is a big draw on resources. The industry isn’t really large enough to support the farms, so in many places, they’re feeding farmed fish impure foods containing vegetable oils and other stuff. These fish do not develop the omega-3 profiles of a wild fish. There’s no government regulation in most countries.” People who eat farmed fish might not be getting the omega’s they bargained for.

Mr. Opheim stressed that Norway has strict requirements that all farmed fish be fed equivalent nutrition to what they’d eat in the wild, so that they develop the right omega-3s. But this is expensive and requires a lot of marine biomass. It can take up to 5 pounds of wild catch to produce 1 pound of farmed salmon—not a very good ratio if you’re trying to protect the aquatic food chain.

“They’re basically strip-mining the oceans to feed the farmed salmon,” says Vital Choice’s Mr. Hartnell. “To get the omega-3 levels, they have to render lots of lower-level fish. Now they’re looking for ways to feed grain to the farmed salmon, but this decreases the omega-3s and increases pro-inflammatory omega-6s.”

The “Seychelles” Study

One year ago, scientists concerned with seafood safety gathered in Washington, DC, for Seafood and Health, a conference sponsored by NOAA. A highlight of the conference was a presentation by Dr. Gary Myers, Professor of Neurology and Pediatrics, University of Rochester, and leader of the widely cited Seychelles Child Development Study.

Dr. Myers evaluated incidence of mercury-related health problems along 60 different endpoints among 700 Seychellois families since 1983. The Seychellois, being Island people, typically eat 10–12 fish/seafood meals per week. Fish there contain similar levels of methyl mercury as do US fish. Mothers in the study had average mercury exposures during pregnancy of 6.9 ppm. If anyone would have seafood-related mercury poisoning, he reasoned, it would be these people.

Dr. Myers’ actually found no mercury-related health/developmental problems other than a couple of weak statistical correlations with no clinical significance.

His work provides an interesting contrast to Philippe Grandjean’s landmark 1997 study of mercury-related developmental problems in the Faroe Islands, where people have a similarly fish-rich diet, though one that also includes a lot of pilot whale. Dr. Grandjean, of the University of Odense, Denmark, found increases in developmental problems in kids with the highest mercury exposures.

The pertinence of Grandjean’s paper for US fish consumption has been debated for nearly a decade. The author himself attributed much of the risk to the whale meat, not the fish. Pilot whales are not only high in mercury, but also PCBs and other toxins.

Fish may process heavy metals differently than marine mammals. Many ocean fish have high selenium levels, while whale meat does not; selenium may cancel the effects of mercury (see Does Selenium Cancel Out Mercury in Fish? below).

“The consensus at the Seafood and Health meeting was that mercury scares are doing more harm than good. The health problems associated with omega-3 deficiencies are far more damaging than the risks associated with mercury in fish,” said Vital Choice’s Mr. Hartnell, who attended the meeting.

He believes environmental groups have emphasized the mercury risk as a way of calling attention to the bigger issue of ocean pollution, which is a valid impulse. “It makes the issue relevant to consumers. Pollution is an issue, to be sure, but people tend to paint the picture with a very broad brush.”

A Blind-Eye on Pollution

Though risk-benefit analyses seem to favor seafood consumption, ED’s Dr. Goldburg urged the medical community not to ignore the very troubling changes in the oceans.

Changes in water pH, coupled with once rare diseases like white-band and black-band disease are destroying coral reefs. Biologists estimate roughly 20% of the world’s reefs are damaged beyond recovery, at least in our life times. Fifteen percent of the world’s total sea grass beds, critical habitats for everything from invertebrates to dugongs, have disappeared over the last decade. Three-quarters of the kelp beds off the Southern California coast have died off in recent years. Dead-zones—oxygen-depleted stretches of water entirely devoid of life—are found with alarming frequency all over the world (for an excellent analysis of the state of our oceans, seek out the April 2006 edition of Mother Jones magazine).

“In the Gulf of Mexico, there’s a huge dead zone the size of New Jersey. It is very disturbing,” said ED’s Dr. Goldburg. The Gulf dead zone is the end result of agricultural runoff from the Midwest, which washes into the Mississippi River and ultimately down to the Gulf. Nitrogen-rich fertilizers in the runoff feed massive algal blooms, which basically suck the oxygen out of the water. “The dead zone in the Gulf has been there for years, but the US has not had the political will to take actions to abate the problem because that means confronting agribusiness.”

Algal bloom problems are compounded by the fact that commercial fishing is destroying one of nature’s primary control mechanisms: filter-feeding organisms.

Consider the menhaden, a rather unglamorous bony fish once plentiful in the Chesapeake Bay. Menhaden swim in schools of hundreds of thousands, mouths open, vacuuming phytoplankton and algae, keeping upper strata of the water clear. This allows light to penetrate, which promotes growth of marine plants. But menhaden are being scooped out of the Chesapeake in football-stadium sized nets and ground up into animal feed, linoleum, soaps, and cosmetics.

What menhaden do for the upper waters, filter-feeding oysters do for the bottom. Or at least they used to. Overfishing and pollution have decimated native Chesapeake oysters.

Eliminate the filter feeders, and you eliminate one of the primary checks on algal blooms. In an interview with Mother Jones, Marine biologist Sara Gottlieb described lowly filter feeders as the “liver” of the oceans; just as the body needs the liver to filter and neutralize toxins, so do the oceans need their filter feeders.

The point is, marine organisms exist for reasons other than human consumption; they are knitted together in an elegant web of reciprocal and multifunctional relationships. Like the relationships between our organ systems, these systems are resilient and able to withstand great stresses, but only to a point. It seems we humans are pushing that point.

Conscious Consumers Are Key

To be sure, we’ll need strong fisheries management and serious local, federal and global environmental policy change to prevent oceanic calamity. The other essential factor is consumer awareness. Marine ecology is complex, and it cannot be reduced to simple “fish good/fish bad” nostrums. People who choose to eat fish need to understand that various fish species differ in their omega-3 profiles, their tendency to store toxins, their relative sustainability in the wild, and the likelihood that they can be farmed ecologically.

This requires meaningful education, not simplistic rhetoric, and physicians can be key players in the education process.

Fortunately, a number of tools have recently become available to help the process. The Marine Stewardship Council is a London-based independent research and monitoring group founded in 1996 that, “is seeking to harness consumer purchasing power to generate change and promote environmentally responsible stewardship of the world’s most important renewable food source.”

MSC, a non-profit group with no industry ties, does comprehensive species assessments in key fisheries throughout the world. The Council established criteria for sustainability and certifies fishing enterprises and seafood companies with an easily identifiable blue sustainability seal that consumers can look for.

A number of conservation institutions, including Environmental Defense and the Monterey Bay Aquarium, publish wallet-sized “Best Choice/Worst Choice” cards that detail which fish have the lowest toxin burdens, the most robust and sustainable populations, and the highest omega-3 levels, as well as which should be avoided due to contamination, over-fishing, or ecologically unsound farming.

Best choices include: wild Alaskan salmon and pollock, wild Pacific halibut, herring, sardines, and farmed arctic char. Fish to avoid include: Chilean seabass, Atlantic cod, Atlantic flounder and sole, grouper, farmed salmon, orange roughy, and red snapper.

“Most of the arguments for fisheries conservation have come from marine biologists or ecologists, but doctors could be an important voice in this,” said Dr. Goldburg. “We need abundant fisheries for everyone’s health, now and in the future. Exploitation of the oceans is bad for public health.”

Does Selenium Cancel Out Mercury in Fish?

One of the scientific nuances that gets overlooked in the contention over mercury in fish is the fact that roughly half of all methyl mercury in the oceans has been there since the dawn of time; it comes from underwater volcanic activity.

Life evolved in a soup that included methyl mercury, though admittedly human industry has added a lot to that in the last century. The point, though, is that higher organisms have biochemical mechanisms for detoxifying naturally occurring trace levels of environmental mercury. One of these appears to involve selenium.

Mercury and selenium have a very high binding affinity for one another; together they form a harmless and excretable selenium-mercury compound. Dr. Nicholas Ralston, of the University of North Dakota’s Energy and Environmental Research Center, has been at the forefront of this line of research. He believes selenium may be able to neutralize the neurotoxic effects of methyl mercury.

The good news for fish-eaters is that wild ocean fish, in addition to being good sources of omega-3s, are also good sources of selenium. The selenium effect may partially explain the low observed rates of mercury associated health problems in the Seychelles study. Selenium obtained in the subjects’ fish-rich diet may have canceled out the impact of mercury to which they were exposed.

It remains to be determined if selenium supplementation has any effect on environmental mercury toxicity. The hypothesis is compelling, but has not yet been tested.

What Makes a Good Fish Oil?

Obtained from Sustainable Species: Though large fish like wild salmon and tuna get the glory as omega-3 sources, reputable fish oil brands obtain their oil mostly from small fish like sardines and anchovies that can be sustainably managed.

Toxin Free: A fish oil manufacturer should be able to tell you what environmental toxins they test for, and what their batch results are. Obviously, good fish oil supplements must be free of mercury, cadmium, lead, PCBs, dioxins and other common toxins.

Cold Processing: High heat is not good for fish, said Nordic Naturals president Joar Opheim. You can lose 60% or more of the omega-3s with high-heat processing. Ideally, fish bound for fish oil production should be processed as soon as possible after catch, using a cold process that prevents both the heat denaturing and the oxidation of the oils.

Freshness: Oxidation is deadly for omega-3s in fish oil; it also turns the oil rancid making it bad-tasting and burp-inducing. Fresh oils will have a clear taste with minimal “fishiness.” There are two widely used freshness measures: peroxide value, which indicates oxidation-in-progress, and anisidine value, which indicates total accumulated oxidation. Both should be as low as possible.
The two oxidation values can be combined as the “Totox” score, which is twice the value of the peroxide measure plus the anisidine value. “Totox should never be over 26,” said Opheim. “Our goal at Nordic is to keep the PV below 1, the AV below 8, and the Totox score below 10.”

Seafood and Marine Ecology Resources

 

Copyright © 2026 Holistic Primary Care. All Rights Reserved.