As can be seen inmale and female pink salmons of similarmass, the concentrations of elements have fewdifferences. At the level 121
of trends, only the content of Zn, Pb and Hg are slightly higher in female individuals. In chumsalmon, inwhich all of the sampleswere 122
much larger than pink salmon, the identified elements were present in larger quantities. Among the fish that were caught, chum 123
females were larger than males, and the concentrations of all of the elements, except copper, were higher than in male individuals. 124
Therefore, in wild fish that gained weight in the ocean, a direct relationship between the weight (and size) of individuals and the 125
content of trace elements is observed. This consistency is disrupted when fish are grown in stocking ponds, where the growth runs 126
in a short period of 12 to 23 months (depending on species) compared with the 2- to 5-year-long life of wild salmon. In a period of 127
rapid and extensive growth, the accumulated contaminants are “diluted” by macronutrients, such as proteins or lipids. Canadian 128
researchers Kelly et al. (2008) found a significant correlation between the concentration of total mercury in fish fillets and its size 129
(kg) for wild Chinook: the mercury content varied from approx. 0.01 ppm for 2 kg fish to 0.1 ppm for 8 kg fish.