Metal concentrations in female and male sperm whales biopsied in the Gulf of Mexico. Sample sizes were as follows, for 2010: 18 males, 22 females; for 2011: 25 males, and 28 females; for 2012: 21 males, and 26 females. Data represented as mean ± standard deviation in units of μg/g tissue. Data are divided into panels solely for optimal visualization. (A,B) Metals with mean skin concentrations less than 1 μg/g for females (A) and males (B), respectively; (C,D) Metals with mean skin concentrations between 1 and 20 μg/g for females (C) and males (D), respectively; (E,F) Metals with mean skin concentrations greater than 50 μg/g for females (E) and males (F), respectively.