Hair sampling location in harbor seals (Phoca vitulina) affects selenium and mercury concentrations: Implications for study design of trace element determination in pinnipeds

► Hair is often used to determine trace elements exposure and status of pinnipeds. ► Few studies have examined how sampling methods affect trace element concentrations. ► We compared Se and THg hair concentrations at two body locations on harbor seals. ► Both elements concentrations differed between mid-dorsal and neck samples. ► The collection site of hair should be standardized for trace element determination.