mercury residues found in the SI study were in the flesh of spotted seatrout
from Hackberry, Cameron Parish, La. The initial analysis by WARF Institute
revealed 2.2 ppm of mercury, four times more than the FDA maximum of 0.5. In a
repeat analysis by WARF, the level was 1.8 ppm. The seatrout were procured from
a commercial fish company in Hackberry, and they had been caught in adjacent
Lake Calcasieu, a brackish body of water connected to the Gulf of Mexico. On
the Gulf coast, seatrout are generally not migratory but localized in one
estuary. Last July after SI obtained the fish, the FDA, in an entirely
unrelated move, halted interstate shipments of crabs, spotted seatrout, redfish
and flounder from Lake Calcasieu because of high mercury levels.
The flesh of
striped bass from California also surpassed the FDA limit on mercury. The
California Department of Fish and Game took the flesh and eggs from 15
different females caught in the Delta near Antioch, composited flesh and egg
samples separately and forwarded them to WARF Institute. The department
retained the remainder of the flesh and eggs for testing on its own. At WARF
Institute initial flesh analysis was 0.70 ppm; the repeat analysis was 0.68. In
order to obtain California striped bass for testing, SI agreed to allow the
California Department of Fish and Game to review the results before publication
and then to comment upon the significance. After reviewing the data, L. H.
Cloyd, deputy director of the department, says that the WARF finding "for
the level of mercury was consistent with one of our state laboratory
reports." Cloyd also points out "the levels of mercury in stripers, as
well as in some catfish, sturgeon—and pheasants—have prompted our governor to
assemble a special task force of state agencies and cooperating federal
agencies to investigate mercury pollution in California."
Mercury in excess
of the FDA limit of 0.5 was also found in the flesh of Spanish mackerel caught
four miles off Charleston, S.C. Initial analysis by WARF Institute was 0.57 in
the flesh; the repeat analysis was 0.56. The Spanish mackerel is a pelagic
fish, one that spends its life near the surface of the ocean and is not known
to frequent shallow water. The fish ranges off the coasts of the Carolinas and
Florida, and it may migrate into the Gulf of Mexico.
Other species had
mercury levels close to the FDA maximum. False albacore from South Carolina,
another pelagic fish, had residues of 0.40 in the flesh; spotted seatrout from
Shell Point Reef on the panhandle of the Florida Gulf coast had 0.40; striped
bass from the Hudson River, 0.34; bluefish from South Carolina, 0.31; and white
perch from the James River, Virginia, 0.31. Little is known about the natural
or normal mercury level in the flesh of fish, but it is probably not more than
300 parts per billion. The lowest level discovered by WARF Institute was 0.10
parts per million found in the flesh of Atlantic mackerel from Long Island
Sound, American shad from the James River and spotted seatrout from South
Carolina. SI did not ask WARF Institute to analyze eggs for mercury
Institute analyzed the egg and flesh samples for DDT residues, dieldrin and
BHC, all chlorinated hydrocarbon pesticides. These synthetic compounds have
several factors in common. They do not readily break down in nature; indeed, it
takes at least a decade for them to lose their toxicity. They are also highly
poisonous to a broad spectrum of living organisms. They are used to attack
insect pests because they can penetrate the external shell of chitin, a thin
layer of hard fatty material that covers an insect body. Once applied, be it on
insects, on the ground, on vegetation or in the air, these long-living
pesticides are spread by wind and water. Aerial applications of DDT can enter
the atmosphere and circle the earth in only two weeks. Last year Drs. Eugene F.
Corcoran and Douglas B. Seba of the University of Miami reported surface slicks
containing pesticides washing into Biscayne Bay after heavy rains. These areas
were several miles long and from five to 300 feet wide, and they contained
10,000 times more chlorinated hydrocarbon pesticides than the water surrounding
into the food web, chlorinated hydrocarbons are able to move up from
phytoplankton to zoo-plankton to fish to bird or mammal, and they become more
and more concentrated as they are retained by a higher level of animals. The
chlorinated hydrocarbons tend to center in the body fats, such as those in the
reproductive organs, and it is generally agreed that these chemicals are to
blame for the current decline in North America of the brown pelican, the
peregrine falcon and the bald eagle, our national symbol. All have fish in
their food web.
In the past two
years the FDA has seized shipments of coho salmon from Lake Michigan and jack
mackerel from the Pacific near Los Angeles for exceeding 5.0 ppm of DDT
residues, and the U.S. Bureau of Sport Fisheries and Wildlife has noted DDT
levels of from 31 to 45 ppm in the flesh of white perch taken from the Delaware
River at Camden, N.J. Last month John MacGregor of the U.S. Bureau of
Commercial Fisheries announced that a federal study of fish from Santa Monica
Bay contained new research information. The study showed DDT residues in those
fish to be astronomically high, ranging from 63 ppm in the liver of Dover sole
to 1,026 ppm in the liver of starry rockfish. A major source of the residues
was two sewage plants emptying into the bay. The City of Los Angeles plant at
Hyperion was releasing one to seven pounds of DDT components per day, while the
Los Angeles County White Point plant was daily discharging from 200 to 400
pounds of DDT residues. However, none of the flesh samples tested for SI by
WARF Institute approached the federal maximum. DDT residues were detected in
the flesh of every species submitted, but the closest to the FDA maximum were
the Hudson River striped bass that had DDT residues totaling 2.42 ppm.
Institute also tested all eggs for chlorinated hydrocarbon residues. Inasmuch
as these pesticides have an affinity for fat, it came as no surprise that there
were higher residues in the eggs than in the flesh. DDT residues in the eggs
can affect reproduction or the survival of young fish. In Jasper National Park,
Canada there was a 70% mortality of brook-trout fry hatched from eggs with 0.46
ppm of DDT residues. In Michigan 700,000 coho salmon fry died in hatcheries in
1968. They had been hatched from eggs with DDT residues of 1.5 to 3 ppm. When
the larval salmon were three weeks old and absorbed their yolk sac during the
so-called "button up" stage they died. DDT residues were in the yolk,
and quickly made contact with the central nervous system. Dr. Philip A. Butler
of the Bureau of Commercial Fisheries Laboratory in Gulf Breeze, Fla. reports
that in a joint study with the Texas Department of Parks and Wildlife virtually
no young spotted seatrout were observed in the Laguna Madre in 1968 and 1969.
The gonads of females had DDT residues up to 8.0 ppm.
of fish seem to have different levels of tolerance to DDT residues in the eggs.
Precise levels are simply not known for most marine fish, but based on the
above 0.5 ppm seems to be cause for concern and 1.5 ppm serious cause for
concern about survival of the young. According to WARF Institute results, the
highest DDT residues in eggs were in the California striped bass, 9.05 ppm.
Commenting upon DDT residues in California stripers, L. H. Cloyd of the
Department of Fish and Game notes: "Numerous studies conducted by our
department of the levels of recruitment of striped bass demonstrate no adverse
effects from the levels of DDT and its metabolites in striper eggs and larvae.
We are, however, continuing to investigate this aspect."
Striped bass from
the Hudson, which migrate to New Jersey, New York and Connecticut coastal
waters, had 7.40 ppm of DDT residues in the eggs. They also had 0.33 ppm of
dieldrin. By FDA standards, the eggs of these striped bass should not be eaten.
Dieldrin is more toxic than DDT, and the FDA has imposed a maximum of 0.30 ppm
of dieldrin on fish products.