Mercury accumulation in Yellowfin tuna (Thunnus albacares) with regards to muscle type, muscle position and fish size

• Published in: Food chemistry Vol. 190; pp. 351 - 356
• Main Authors: Bosch, Adina C., O’Neill, Bernadette, Sigge, Gunnar O., Kerwath, Sven E., Hoffman, Louwrens C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2016
• Subjects: Animals; Cross-carcass variation; Fish muscle; HPLC–ICP-MS; Mercury - analysis; Mercury - metabolism; Mercury speciation; Methylmercury Compounds - analysis; Muscles - metabolism; Size effects; Tuna - metabolism; Yellowfin tuna; Size effects; HPLC–ICP-MS; Yellowfin tuna; Mercury speciation; Fish muscle; Cross-carcass variation
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2015.05.109

•No variation in Hg species accumulation was detected within the white muscle.•tHg and iHg had higher concentrations (p<0.001) in dark muscle than white muscle.•Positive linear correlations between fish weight and both tHg and MeHg were found.•Yellowfin tuna above 70kg fresh weight are likely to exceed the tHg maximum limit. The concentrations and relationships between individual mercury species and total mercury were investigated in different muscle parts and sizes of Yellowfin tuna (Thunnus albacares). Fourteen Yellowfin tuna caught in the South Atlantic off the coast of South Africa had an average total Hg (tHg) concentration of 0.77mg/kg wet weight. No differences were detected (p>0.05) in tHg, MethylHg (MeHg) or inorganic Hg (iHg) accumulation among the four white muscle portions across the carcass, but both tHg and iHg were found in higher concentrations (p<0.001) in dark muscle than white muscle. Positive linear correlations with fish weight were found for both tHg (r=0.79, p<0.001) and MeHg (r=0.75, p<0.001) concentrations. A prediction model was formulated to calculate toxic MeHg concentrations from measured tHg concentrations and fish weight (cMeHg=0.073+1.365·tHg−0.008·w). As sampling sites and subsampling methods could affect toxicity measurements, we provide recommendations for sampling guidelines.