hydrocarbons is that involving the analyses of liver tissue for the 
activity of detoxifying enzymes. Both of these tests have demonstrated 
that fish from Eagle Harbor and the Duwamish Waterway had been 
contaminated significantly with hydrocarbons. 
Sister chromatid exchange . A test similar to the anaphase aberration 
bioassay of sediment extracts has been used in Puget Sound with fish. 
Sister chromatid exchanges are among the types of chromosome damage that 
can be caused by mutagens. These mitotic mistakes have been observed in 
the kidney cells of English sole captured in the Duwamish Waterway at 
prevalences significantly exceeding those of fish from rural sites. 
Impaired reproductive success among fish . Recent studies have provided 
preliminary evidence that the reproductive success of some English sole in 
the Sound may be impaired by certain contaminants. This research is 
continuing. 
Health of marine birds . Studies of several species of resident marine 
birds in 1983 showed that among the many hundreds of chemicals in Puget 
Sound, only a few (notably PCB, lead, mercury) appeared in the tissues of 
marine birds. The PCB concentrations in some eggs and adults were very 
high. Studies completed in 1985 set out to determine if the birds were 
suffering any major effects. Focus was placed upon tests of reproductive 
success, histopathological disorders and changes in population size among 
Glaucous-winged Gulls, Great Blue Herons and Pigeon Guillemots. Clutch 
size and hatching success were about equal among colonies near the urban 
bays and in the remote areas. Parasitism was somewhat higher in birds 
caught near urban bays than in those from remote areas. Gulls from the 
Duwamish area appeared to have enlarged livers compared to those from 
elsewhere. The thickness of heron eggshells collected in 1984 had 
apparently decreased Sound-wide, relative to 1947 values. 
So, while some individuals may have shown some subtle signs of stress, the 
populations, overall, appeared to be doing well. Population sizes of 
resident Great Blue Herons, Glaucous-winged Gulls and Pigeon Guillemots 
appeared to be equal to or greater than those recorded historically. 
However, the possibility exists that some types of effects were occurring 
that were not measured, since most of the birds that were studied were 
outwardly apparently healthy. 
Health of marine mammals . The Strait of Juan de Fuca/Puget Sound region 
is home year-round for about 3,000 to 4,000 harbor seals and is visited 
periodically by other seals, sea lions, porpoises, killer whales, minke 
whales, and other whales. Since the harbor seals live in the Sound 
year-round, they have been studied most intensively. As was observed in 
marine birds, these seals seem to concentrate very few chemicals in their 
tissues relative to the variety found in the Sound. Concentrations of 
PCBs in most seals are comparable to those encountered by scientists at 
many places throughout the world. However, some animals collected in 
the mid-1970s had relatively high PCB concentrations in their blubber. 
Studies conducted in 1984 showed that seals from Gertrude Island (south 
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