Bluefin Tuna (Thunnus thynnus L.) Muscle

Overview

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Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

tuna was below the legal limit (1 mg/kg, wet weight, w.w.) for all specimens (0.6 ± 0.2 mg/kg),
whereas the wild ones had a content over the limit (1.7 ± 0.6 mg/kg); Se concentration was higher in
genotoxicity and endocrine disruption on a wide range of vertebrates, including fish (3,4), and
methylmercury (90%) and this percentage does not vary by age of the fish.
accounting for about 65% of the world’s mercury reserves, even if it covers only about 1% of the world’s
(FAO) and World Health Organization (WHO) in fish for human consumption (1 mg/kg, wet weight,
at levels lower than the legal limit (1 mg/kg). Moreover, the apical species could show a lower Se:Hg
sampled. The overall mean length was 228 ± 33 cm (males: 240 ± 31 cm, females:
mean body weight was 238 ± 93 kg (males: 279 ± 86 kg, females: 198 ± 83 kg). Sex of fish was 216 ± 31 cm). The
body weight were measured for all tuna fish sampled. The overall mean length was 135 ± 23 cm
(males: 129 ± 11 cm, females: 133 ± 11 cm). The overall mean body weight was 45 ± 26 kg (males:
99.998%) as the oxidant gas. The Hg vapours pass through a catalyst, and the products of combustion
95051, USA) equipped with Zeeman background correction. Argon with a purity of 99.998% was
Se:Hg molar ratio, from the average Se and average Hg levels in each individual fish (see Tables S3
applied to find significant differences between groups at the 95% confidence level (33,34). Relationships
All results are expressed in wet weight (w.w). Tables 1 and 2 show biometric measurements
Table 1. Biometric measurements of farmed Atlantic bluefin tuna (ABFT).
Table 2. Biometric measurements of wild ABFT.
(<1%). For DORM-2 analysis (n = 8), Hg and Se are in agreement with certified values (p-values
generally >0.05): Hg 4.58 ± 0.10 mg/kg and Se 1.40 ± 0.09 mg/kg against certified mean values Hg
Total concentration of Hg in muscle tissue of farmed tuna is 0.6 ± 0.2 mg/kg. Concerning
Hg concentration between male and female (0.6 ± 0.2 mg/kg vs. 0.6 ± 0.2 mg/kg respectively).
Total concentration of Hg in muscle tissue of wild tuna is 1.7±0.2 mg/kg. Even in this case no
male and female (1.5 ± 0.5 mg/kg vs. 1.9 ± 0.7 mg/kg respectively). Even the relationship between
Se total concentration in farmed tuna was 1.1 ± 0.9 mg/kg. Male and female specimens show no
differences in Se content with mean values of 1.3 ± 1.0 mg/kg and 0.9 ± 0.7 mg/kg respectively (t =
Wild tuna showed a Se total concentration of 0.6 ± 0.3 mg/kg with no statistical differences
between male and female specimens (0.7 ± 0.3 mg/kg and 0.6 ± 0.3 mg/kg respectively) (t = 0.837801,
0.5 mg/kg). There are different possible explanations for this result t. The first one is ascribable to
scombrus, and Atlantic herring Clupea harengus that show Hg levels <0.05 mg/kg (37). Therefore,
months, a weight 40% higher than the original one, and with a high amount of accumulated lipids for
(farmed: 1.1 ± 0.9 mg/kg w.w. vs. wild: 0.6 ± 0.3 mg/kg w.w.) with a statistically significant
Figure 2. Relationship between Hg concentration (mg/kg w.w.) kg
Figure 2. Relationship between Hg concentration (mg/kg w.w.) and body weight (kg) in farmed tuna.
Figure 2. Relationship between Hg concentration (mg/kg w.w.) and body weight (kg) in farmed
Figure 3. Relationship between Hg concentration (mg/kg w.w.) and body weight (kg) in wild tuna.
Figure 3. Relationship between Hg concentration (mg/kg kg body weight (kg) in wild tuna.
(w.w). Our results demonstrate that almost all farmed tuna (93%) show Hg levels below the established
limit, whereas for wild ones only 9% are deemed safe according to mercury levels. Regarding with Se,
Table 3 summarizes the literature data on Hg and Se in tuna sampled in the Mediterranean or
levels in fish varies normally between 0.2–0.9 mg/kg (48) with good concentrations reported in apical
showed a value of 1.32: no other results less than 3 are reported in Table 3. Even if some authors

Methods (brief)

by atomic absorption spectrometry after microwave digestion of the samples. Hg content in farmed
Keywords: Atlantic bluefin tuna; Mediterranean Sea; selenium; mercury; atomic absorption
its concentration in all specimens sampled, to evaluate the differences due to different diets and to
Sample Collection and Treatments
Collection andsampled under the guidelines Art 36, par.1 Reg (EU) N° 508/2014 (27). The
The animals were sampled under the guidelines Art 36, par.1 Reg (EU) N◦ 508/2014 (27).
Samplingsamples of ABFT Thunnus thynnus specimens were caught by purse seine from
samplesaround theThunnus
upper jaw to the fork of the caudal fin) and total body weight were measured for all tuna fish sampled. the tip of the
sampled. The overall mean length was 228 ± 33 cm (males: 240 ± 31 cm, females:
samples examining gonads
then stored at −80 C until analysis. For each specimen, three independent samples of muscle (about on dry ice, and
were until analysis. For each specimen, three independent samples of muscle (about
10 g each) were collected.
Wild samples of ABFT were caught by traps around the island of Sardinia, in Carloforte Tonnare
sampled. Curved fork length (from the tip of the upper jaw to the fork of the caudal fin) and total
body weight were measured for all tuna fish sampled. The overall mean length was 135 ± 23 cm
under a dissecting microscope. Muscle samples were obtained from the dorsal part near the back,

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised