Page 845 - The Toxicology of Fishes

Reproductive Impairment of Great Lakes Lake Trout by Dioxin-Like Chemicals 825

25
Total PCB (µg/g ww)
Lake Trout - Lake Michigan
20
Total PCB (µg/g ww) 15

10

5

0
1970 1980 1990 2000
A
22
Total DDT (µg/g ww)
20
Lake Trout - Lake Michigan
18
16
Total DDT (µg/g ww) 14

12
10
8
6
4
2
0
1970 1980 1990 2000
B

FIGURE 21.3 Concentrations (µg/g ww) of (A) total polychlorinated biphenyls (PCBs) and (B) 2,2-bis(p-chlorophenyl)-
1,1,1-trichloroethane (DDT) in lake trout from Lake Michigan, 1970 to 2000. (Data are from DeVault, D.S. et al., J. Great
Lakes Res., 22, 884–895, 1996; Hickey, J.P. et al., Arch. Environ. Contam. Toxicol., 50, 97–110, 2006.)

slow release of these contaminants from sediments in point-source river beds. Concentrations of both
PCBs and DDT in lake trout from Lake Michigan have declined greatly, from a maximum of greater
than 20 mg/kg in 1973 to a current average of approximately 1.0 mg/kg (Figure 21.3). The rate of
decrease in concentrations of PCBs during the last two decades of the 20th century was greatest in fish
from Lake Michigan compared to the other Great Lakes (Hickey et al., 2006). Concentrations of both
PCBs and DDT in lake trout from Lake Superior have always been the least of all of the Great Lakes
(Baumann and Whittle, 1988).
The concentrations of AhR agonists in the Great Lakes food web have declined over the past four
decades; however, with the exception of PCB concentrations, documentation of these declines in Great
Lakes fish is not as complete as that of organochlorine pesticides. The information on temporal trends
in PCDD and PCDF concentrations in Great Lakes fish is limited. A single monitoring program that has
sustained measurements of these analytes in Great Lakes fish does not exist; however, based on the
various studies that have been reported on the concentrations of PCDDs and PCDFs in fish, declines
appear to follow those of organochlorine pesticides and PCBs. DeVault and coworkers (1989) reported
concentrations of HAHs in lake trout collected in 1984 from Lakes Michigan, Ontario, Huron, and
Superior and in walleye collected from Lake Erie that same year. The concentrations of PCDDs and