Total Mercury Content—Fish Weight Relationship in Swordfish (Xiphias gladius) Caught in the Southwest Atlantic Ocean

The total mercury content in the edible part of swordfish (Xiphias gladius) was determined in 192 specimens ranging from 10 to 412 kg, in the period January 1997–December 1999. Total mercury values between 0.04 and 2.21 mg kg−1, with a mean value of 0.62±0.35 mg kg−1, were obtained. Data were analyzed in two subsets. One of them, for specimens under 100 kg, yielded a mean value for total mercury content of 0.53±0.02 mg kg−1, and the other, for specimens above 100 kg, had a mean value of 0.94±0.06 mg kg−1. The existence of these subsets of data is related with the rate of mercury incorporation into swordfish flesh, in accordance with a potential model for total mercury bioaccumulation. Swordfish weighing below 100 kg can be considered safe for human consumption, according to international regulations.