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FRESH AND SALTWATER SEAFOOD AND THE ENVIRONMENT

As wild creatures, fish and shellfish live in their native environment, consume their natural diets, and are among the foods we are best adapted to eat. But because environmental pollutants may contaminate them, they should be selected with care. This chapter provides an overview of the water pollution problem and of influences affecting the quality and flavor of seafood in general. A more thorough guide to understanding and selecting fish and shellfish for both enjoyment and maximal health benefits is provided in appendix 2, where particular attention is paid to the issue of how one may determine which species are likely to have been least affected by water pollution as well as specific nutrient characteristics.

WATER POLLUTION

Many highly toxic pollutants contaminate coastal waters and even the deep oceans. These chemical compounds and heavy metals accumulate in the fats of fish. Many shellfish particularly concentrate pollutants because they constantly filter water. Thus fatty fish and shellfish are often avoided by many people; in recent years, a misbegotten fear of cholesterol and all animal-sourced fats has added to concerns. Fears about pollutants in fish and shellfish are more reasonable.

People have always used waterways for waste disposal. In earlier times, fewer people used fewer chemicals and created less sewage; many chemicals now widely used did not even exist back then. Today sewage, industrial wastes, detergents, and other pollutants (many highly toxic) are discharged into rivers, lakes, and oceans.

Treatment of sewage fails to adequately remove nitrates and inorganic phosphates. These major pollutants lead to eutrophication, an excessive growth of algae that decays in slow-moving estuaries, rivers, and bays. The resultant foul-smelling substances are toxic to fish, shellfish, and other wildlife that live in these coastal areas or must pass through en route to breeding grounds.

Agricultural fertilizers and spray residues include chlorinated hydrocarbons such as DDT and organophosphates such as parathion and malathion. Organophosphates are related to nerve gases developed in Nazi Germany during World War II. These substances all reach water via seepage and runoff. Wind carries mercury and other poisons in dust that is blown from chemical factories near waterways. Discharge of wash water and industrial wastes, dumping of trash and highly toxic chemicals, and oil spills are the other principal modes of contamination of coastal areas.

The principal industries contributing to this are the paper industry in the Pacific Northwest, Alabama, and Mississippi; chemical plants in the Gulf and mid-Atlantic states; and the oil industries in New Jersey, Louisiana, Texas, and California. All are concentrated at seashores or on large rivers, and much of the wastes discharged do not receive any type of treatment. Mercury, nickel, fluoride, oil, cement, white lime, caustic soda, hydrocyanic acid, and lactonitrile are among the many items discharged in large quantities.

Drums containing highly toxic materials, especially chlorinated hydrocarbons, have been dumped a few miles offshore from major coastal cities. They eventually leak.

Millions of tons of oil have been spilled into the world’s oceans, mostly in coastal areas. The resulting oil-laden sediments move considerable distances with bottom currents. For as many as seven years after a spill, oil has been shown to be incorporated into the body tissues of crabs in sufficient quantities to drastically affect their behavior, reproductive capacity, and ability to survive.

Mercury and PCBs (polychlorinated biphenyls) are two industrial pollutants of particular concern because of their ubiquitous presence in the environment. Mercury is also used in agriculture; millions of pounds of mercury marketed yearly in the United States wind up in croplands. Although the Food and Drug Administration prohibits the sale of foods containing mercury, tests show grains, apples, eggs, milk, and other products contain levels in the range of 0.01 to 0.1 ppm. The World Health Organization suggests a maximum of 0.05 ppm.

Once in waterways and the sea, mercury is absorbed into plankton and moves up the food chain. Highly carnivorous species that live for several years and grow large acquire the densest concentrations of it. Although living in open ocean, tuna and swordfish are especially susceptible; the metal concentrates in the fats of these large fatty carnivorous fish.

PCBs are used in transformers and capacitors, as hydraulic and heat-transfer fluids, as plasticizers and solvents in adhesives, and as sealants. In the 1970s, four thousand tons entered waterways yearly, largely through sewage, leaching of industrial fluids, and from landfills and dumps. An outbreak of illness in 1968 in Japan was called yusho, or rice-oil disease, because the patients had eaten rice oil contaminated with tetrachlorobiphenyl (a PCB), which had leaked from the pipe of a heat exchanger during manufacture of the oil.

The patients numbered about one thousand. They developed darkened skin, a cheese-like discharge from the eyes, severe acne, numbness, nerve pains, swollen joints, edema, and jaundice. Among the eleven live and two stillborn babies born of these patients, all but one showed at least some of these symptoms. The disease lasted in many cases for more than three years. Shortly before these people became ill, seven hundred thousand chickens had been contaminated and died of the disease.

The patients had each consumed from 0.5 to 2.0 grams of the PCB; fat tissue from the skin contained from 13.1 to 75.5 ppm of the substance. (One-tenth of a teaspoon equals 0.5 grams.) Thus great harm may be done by small amounts of PCBs. Concentrations may vary widely within the same area. While apparently some PCBs and mercury are found in seafood from even the most remote waters, a dramatic difference in the concentration of poisons is based on the life history of the seafood consumed.

Species spending most of their lives in deep waters far out at sea are most likely to be least contaminated; coastal species living in polluted waters are most contaminated. Shellfish and fatty fish especially should be from relatively unpolluted waters.

Also, as we have mentioned, pollutants become more concentrated in fish that are higher up the food chain, making smaller species more desirable. Smaller, deep-water fish include herring, sardines, and anchovies; the smaller salmon such as pink, coho and sockeye; some members of the cod family, including scrod, hake, haddock, and pollock; and mackerel, pompano, red and yellowtail snapper, striped bass, butterfish, squid, octopus, and tilefish, among others. Tuna, bluefish, swordfish, and king salmon are best eaten when taken from waters off coastlines in unindustrialized areas. A wide variety of anadromous fish (oceangoing species returning to rivers to breed) are best eaten when taken in the unpolluted bays and rivers of unindustrialized and lightly populated areas, as are freshwater fish from similarly located lakes and streams.

The habitat of most commonly eaten shellfish is coastal waters. Since all are bottom dwellers, and since bivalves such as oysters and clams constantly pass water through their systems to filter nutrients, shellfish in contaminated waters concentrate undesirable substances. A knowledge of the waters shellfish are taken from is thus imperative when judging their desirability. Good fish merchants know where their stock is from.

GUIDELINES FOR PURCHASING SEAFOOD

I remember a small fish market I once frequented many years ago on the docks of the fishing village of Menemsha on the island of Martha’s Vineyard off the coast of Massachusetts. The cement floors were always wet from a recent rinsing, a sea breeze blew through open windows, and out the back door one saw fishing boats tied up at docks. Fish eyes shined and scales glistened; fish on ice in glass cases were so fresh they looked almost alive, and all one could smell was the ocean and the faint sweet fragrance of prime seafood.

That is quality.

When examining a whole fish, first look at the eyes, which should be clear and full. If milky and sunken, look no further; this fish is not fresh. The flesh when pressed should be firm, rather than soft—one’s fingers should leave no indentation. A clean fragrance, unblemished skin color, and bright red gills confirm the diagnosis of fresh fish. Fillets or steaks should appear clean, crisp, moist, and firm. Yellowing, a dried out appearance, or any strong odor indicate lack of freshness.

Less oily species generally keep well longer than those with a high oil content. Few species have more than about 15 percent fat content; those that do include herring, mackerel, and some varieties of salmon at certain times. The fat content varies greatly with both the diet of the fish and the season, most species being prime in fat and flavor in autumn. The seasonal variation is greatest among larger fish.

Any species may be excellent in one area and poor in another. The presence of pollutants in the water; various types of algae; the foods available to the fish in the locale; seasonal variations in fat content, freshness, seasoning, and method and amount of cooking all combine to determine whether a given fish lives up to the potential for the species.

The species with the most health benefits may be those found in more northern waters, perhaps because of their higher EPA content, and I generally recommend seafood from northern waters over tropical and subtropical species. However, I’ve never found any problems with eating the tropical and subtropical species as well. Avoid farm-raised fish because of the use of chemicals and artificial feed.

Seafood has been central to the lives of all traditional people who lived near the ocean. In many native cultures, fish and other animals of the hunt were in a very real sense worshipped—considered to be sacred food. Procuring and eating the wild creatures of the sea and the land was a sacrament, a sacred and ritualistic series of acts of great spiritual as well as physical significance. This sense of the sanctity of all life, of the essential oneness of the hunter and the hunted, of human and animal, is totally lost on most modern people. Ultimately, this loss of sanctity in our lives, of spirit—of love, if you will—is the reason we suffer, first emotionally and eventually physically. As we consider the constituents of an ideally healthy native diet, I believe we must give equal consideration to the spiritual aspects of food and eating—indeed, of living—which were an integral part of native cultures everywhere. If we do not, our efforts to attain health through diet alone will ring hollow and, I believe, ultimately fail.

Next we will turn to dairy foods, first conventionally produced products that are best avoided. Modern mass production methods unfortunately have taken much that was good out of these foods. As with meat, however, a growing number of producers are making grass-fed, high-quality dairy foods available. In the following pages, in our ongoing quest for enhanced health, we will examine conventionally and alternatively produced milk and milk products.