257 



Results 



Quality Assurance 



The results of the quality assurance analyses of mercury measurements of various 

 environmental samples are shown in Table II. Accuracy and precision of the measurements 

 are within acceptable limits of expectation. The sampling precision values for plankton and 

 water are high and may be due to variant flow conditions encountered and values near the 

 detection limit (for water). 



Table II. Analytical Characteristics of Mercury Measurements* 



•Numbers in parentheses refer to the number of samples or sample pairs associated with the entry. 



''Precision divided by mean measurement x 100%. 



Precision for fish is based on replicate analyses of the same fillet 



''Certified reference materials are as follows: walleye - Nat. Res. Cncl., Canada EKDRM-l dogfish 



muscle; water - Nat. Bureau of Stds 1641b water; and sediment - Nat. Bureau of Stds 1645 



Buffalo R. sedimenL 

 'Includes Sl Louis River water samples from Sorensen eial. (1992a) 



An additional check was made for internal consistencies in the data by testing the 

 relationships among fish size parameters Gength, weight, and age). Plots of these 

 relationships are shown in Figures 2, 3. and 4 where power curves (Y=A*X^) have been fined. 



The weight vs length plots in Figure 2 show no significant outlier points relative to the fitted 

 curves. However, numerous departures from the fitted curves (suggesting varying growth 

 rates) are found in Figures 3 and 4 where length and weight are plotted against age. This is 

 especially true for the case of channel catfish where several weights (or lengths) are 

 significantly above the norm. Many of those outliers (dark circles) are from channel catfish 

 taken fixim the Fond du Lac Reservoir (site 1610). 



Mercury in Fish. Summaries of fish mercury concentration statistics for each species across 

 all sites are given in Table III and a summary of species length, weight, and age are given in 

 Table IV. Individual results for each fish are given in Appendix B. 



