Total and Methyl Mercury Concentrations in Antarctic Toothfish (Dissostichus mawsoni): Health Risk Assessment

Abstract

The concentrations of total mercury (THg) in different organs of the Antarctic toothfish (Dissostichus mawsoni) collected from CCAMLR research blocks in Subarea 88.3 and Division 58.4.1 off the coast of Antarctica were determined. The results revealed THg concentrations of 0.165 ± 0.095 mg/kg (0.023-0.454 mg/kg, wet weight) in the Antarctic toothfish. In muscle, methyl mercury (MeHg) accounted for approximately 40% of the THg. In a comparison analysis, muscle and liver tended to bioaccumulate the highest levels of THg, and both THg and MeHg contents showed correlations with fish length and weight. Compared with international guidelines, fish contained 2.5-6.4% and 4.0-10.3% of the provisional tolerable weekly intake for THg recommended by the Joint FAO/WHO Expert Committee on Food Additives and the tolerable weekly intake for MeHg proposed by the European Food Safety Authority, respectively. These results suggest that consumption of the Antarctic toothfish presents no health risk to humans.

High mercury levels in Antarctic toothfish Dissostichus mawsoni from the Southwest Pacific sector of the Southern Ocean

“…Other studies conducted between these years are more consistent with earlier results, reporting mean mercury levels below 0.25 mg kg -1 in the southwest Pacific sector and elsewhere in the Southern Ocean (Son et al 2014, Yoon et al 2018. We calculated the size of fish using allometric equations, while previous studies used measurements of whole fish (Hanchet et al, 2012;Son et al, 2014;Yoon et al, 2018). This may have contributed to the lower mean size of fish in our study.…”

“…The model was not improved by the inclusion of either depth (p≈ 1.00) or standard length (p≈ 0.67) (Annex 1). There was little difference between intercepts for different levels of the grouping variable, longline (variance = 0.0006), and the similar values for R 2 m and R 2 c confirm that the fixed effect variables explain almost all of the explained variability ( Mean mercury levels in D. mawsoni muscle recorded in the current study were higher than those reported in all previous studies (Hanchet et al, 2012;Son et al, 2014;Yoon et al, 2018). The highest single value in this study (1.94 mg kg -1 wwt) was almost 3 times higher than the previous maximum value [~0.70 mg kg -1 in D. mawsoni captured in 2006 (Hanchet et al, 2012)].…”

“…Furthermore, regular commercial fishing in different Southern Ocean regions (CCAMLR, 2018) provides a way to monitor multiple areas. Although this fishery began in 1997, mercury levels have so far only been assessed for five seasons (1998, 2006, 2012, 2016 and 2017) (CCAMLR, 2018;Hanchet et al, 2012;Son et al, 2014;Yoon et al, 2018).…”

“…kg -1 in 1998, ~0.17 mg kg -1 in 2006 and 2012 and ~0.20 mg kg -1 in 2016) (Hanchet et al, 2012;Son et al, 2014;Yoon et al, 2018), but have remained below the upper food safety limit of 0.5 mg kg -1 for most marine species recognized by several agencies (EC, 2006;FSANZ, 2004). These previous studies provide limited information about how mercury levels vary between locations and how this interacts with the size and age of fish.…”

Productivity and Change in Fish and Squid in the Southern Ocean

“…The main comprehensive source of information on Hg bioaccumulation in Southern Ocean squid is the recent work by Seco et al (2020), which documents the concentrations of total, and proportions of organic, mercury in the tissues of 8 squid species caught around South Georgia between 2007 and 2017. While several studies have shown that Patagonian toothfish D. eleginoides have elevated mercury levels (Méndez et al, 2001;McArthur et al, 2003;Guynn and Peterson, 2008), Hanchet et al (2012), Son et al (2014), andYoon et al (2018) reported lower levels of mercury concentrations for the Antarctic toothfish D. mawsoni, usually not exceeding the 0.5 mg kg −1 food safety threshold.…”