242 



Aqiicitic Ecosystems — Our Liviiii; Kc'sniirces 



Contaminant 

 Trends in 

 Great Lakes 

 Fish 



by 



Robert J. Hesselberg 



John E. Gannon 

 National Biological Service 



The Great Lakes region is home to many 

 large industrialized cities and extensive 

 agricultural areas that produce and use an array 

 of potentially toxic cliemicals. Some of these 

 chemicals entering the lakes" food chain have 

 been related to environmental health problems 

 including poor egg-hatching success, reproduc- 

 tive abnormalities, and birth defects in fish, 

 fish-eating birds, and mammals. Tumors and 

 other deformities in some fish and wildlife 

 species are also attributed to exposure to toxic 

 contaminants. In addition, fish consumption 

 advisories are issued annually by the Great 

 Lakes" states and the Province of Ontario for 

 certain fish species and larger sizes of Great 

 Lakes fish that accumulate toxic contaminants. 



To measure progress in reducing chemicals 

 in the Great Lakes ecosystem, the National 

 Biological Service"s (NBS"s) Great Lakes 

 Science Center began a contaminant trend-mon- 

 itoring program in Lake Michigan in 1969. The 

 program was expanded in 1977 to include all of 

 the Great Lakes and additional species of fish 

 through a cooperative agreement between the 

 NBS Great Lakes Science Center and the U.S. 

 Environmental Protection Agency (USEPA). 

 Great Lakes National Program Office. Fish are 

 sampled for this program from 12 sites. All sites 

 were sampled annually through 1982 and there- 

 after were divided into odd- and even-year sam- 

 pling regimes. Results from these long-term 

 monitoring programs are extremely valuable in 

 understanding the dynamics of contaminants, 

 developing predictive models for contaminant 

 trends, and determining the effectiveness of reg- 

 ulatory programs. 



This article presents data from the top preda- 

 tors sampled during even years for the 



Fig.l 



spots" 



, Sampling sites for the NBS/LISEPA Fish Contaminant Monitoring Program and "hot 

 of sediment contamination where tumors and other deformities ha\'e been detected in fish. 



NBS/USEPA monitoring program, lake trout 

 {Salvelinits iiiinuiycusli) or walleye 

 {Stiz(>s!ccli(m vilrfiiin vitreiiin. Lake Erie only). 

 In addition, information is presented on loca- 

 tions in the Great Lakes where tumors and other 

 deformities in fish have been observed, indicat- 

 ing potentially contaminated sediments. 



Methods 



Lake trout from 600 to 700 mm (23.6-27.6 

 in) total length were collected from Lakes 

 Superior, Michigan, Huron, and Ontario from 

 even-year sampling sites by using gill nets (Fig. 

 1 ). Walleye from 400 to 500 mm ( 15.8-19.7 in) 

 total length were collected from Lake Erie near 

 Sandusky, Ohio, by using gill nets I Fig. 1 ). All 

 fish were stored frozen until analyzed. Fish 

 were prepared for analysis by thawing, com- 

 positing fish into five samples, and homogeniz- 

 ing. Contaminants were extracted and separated 

 into nonpolar (polychlorinated biphenyls 

 [PCBs]) and polar (DDT [sum of DDT, DDE, 

 and DDD] and dieldrin) fractions and analyzed 

 by a gas chiomatograph equipped with an elec- 

 tron capture detector. Contaminants were 

 reported as total DDT. total PCBs. and dieldrin. 



Tumor surveys were conducted by the NBS 

 Great Lakes Science Center and other agencies 

 in highly industrialized rivers and harbors. Most 

 of the work focused on the brown bullhead 

 {Ameiitnis nebulosiis), a bottom-feeding fish 

 especially exposed to tumor-causing chemicals 

 in contaminated sediments. 



Contaminant Trends 



Results of DDT. PCB. and dieldrin trends 

 during an approximately two-decade period are 

 presented in Figs. 2-6. Data are from De Vault et 

 al. 1985; Hesselberg et al. 1990; and De Vault 

 and Hesselberg. in press. In general, concentra- 

 tions of contaminants in fish consistently 

 declined until the mid-l980"s, but since then the 

 downward trend has leveled off. Similar trends 

 have been observed in fish in Canadian waters 

 of the Great Lakes (Baumann and Whittle 

 1988). 



Lake Michigan 



Contaminants were higher in Lake Michigan 

 lake trout than in fish of any of the other Great 

 Lakes. Both total DDT and PCBs declined (Fig. 

 2), yet total PCBs did not decline after the vol- 

 untary contiol in 1972 but did after the manda- 

 tory ban in 1976. 



In lake trout dieldrin reached a high in 1978 

 and a low in 1987 (Fig. 2). Dieldrin is higher in 

 Lake Michigan fish than in fish from the other 



