Effects of Age, Fulton's Condition Index (K) and Muscle Fat on Total Mercury Content in Raw, Pre-Canning and Canned Samples of Atlantic Bluefin Tuna (Thunnus thynnus).

A total of 30 samples of Atlantic bluefin tuna were analysed for total mercury concentration. Relationships between total mercury content and age, Fulton's condition index (K) and fat content were statistically evaluated. The effect of muscle status (raw, pre-canning, canned) on mercury content was also investigated. The average total mercury content was: 1.185 ± 0.662 mg/kg in raw, 1.481 ± 0.893 mg/kg in pre-canning and 1.393 ± 0.882 mg/kg in canned samples, respectively. Canning promotes a statistically significant increase in the concentration of mercury. The weight of fish, K and fat content are useful tools to estimate the mercury accumulation in Atlantic bluefin tuna. The results of the present study represent a contribution to the assessment of the EU mercury levels in Atlantic bluefin tuna.

A representative sampling of tuna muscle for mercury control.

The mechanisms of mercury accumulation and distribution in fish tissues are related to its high affinity for sulfhydryl groups in proteins. There is evidence that mercury is distributed unevenly based on the different reactivity of these groups in the various muscle proteins. Tuna fish also shows numerous specialized anatomical features including the structure of the swimming muscles and some form of endothermy, which generates variations in the mercury content between dark and white muscle and between muscle tissues with different lipid content. The aim of the study is to verify, through a suitable sub lot of Thunnus thynnus caught by a static trap in south-western Sardinia, the effective uneven distribution of mercury in the various muscles and also identify the sites representative of the entire carcass. In agreement with other authors, the results show that even in the Bluefin tuna of the Mediterranean, the site "anterior extremity of upper loin (schienale in Italian)" is representative of the mercury average content of muscle tissues as a whole.

A case study on the development of representative sampling procedure to determine mercury levels in a lot of tuna caught by static trap.

Mercury contamination in fish products, and in large pelagic predatory fish in particular, is a remarkable food safety issue that affects fish industry. A lot made up by Bluefin tunas caught at Porto Paglia - in the south-western coast of Sardinia - was subject to several sessions of fish meat official sampling, as disputable results of mercury level determination suggested a potential non-compliance to maximum allowable limit. Local competent Veterinary Service reviewed the sampling procedure introducing more rigorous details including the identification of a specific muscular portion as sampling site, after having taken into account both statutory provisions laid down by Regulation (EC) No 333/2007 and available scientific evidence on variables affecting uneven distribution of mercury across tuna carcasses. This case-study aims to provide an initial contribution in order to ensure an appropriate and representative field sampling protocol of tuna lots that are to be analysed for mercury content.

A case study on the labeling of bottarga produced in Sardinia from ovaries of grey mullets (Mugil cephalus and Mugil capurrii) caught in Eastern Central Atlantic coasts.

The aim of this case study is to show how traditional and molecular methods can be employed to identify the Mugilidae species currently used in Sardinia (Italy) to produce the traditional bottarga for the processing of their ovaries. A total of six specimens of Mugil cephalus (n=3) and Mugil capurrii (n=3) were subjected to external morphology and meristic measurements. Subsequently, tissue samples of white muscle and ovaries from three individuals per species were underwent PCR-sequencing assay of mitochondrial DNA cytochrome oxidase subunit I (COI). The external morphology and meristic characters showed a sufficient level of reliability in the identification between the two species. At the same time, the molecular techniques showed the discriminatory power and confirmed the correct species identification in all the sampling units. DNA barcoding may be an effective aid to traditional taxonomy and can facilitate accurate species identification among the Mugilidae.

Mislabelling and Species Substitution in Fishery Products Retailed in Sardinia (Italy), 2009-2014.

Mislabelling and species substitution are major concerns for fishery products marketed in the EU. The present survey aimed to investigate the correct enforcement of the Community and National rules on the labelling and marketing of fishery products retailed in Sardinia (Italy) between 2009 and 2014. A total of 3000 labels for fresh unpacked fishery products have been considered. A total of 900 labels (30%) presented non-compliance concerning the wrong trade name, the wrong or missing information about the catch area and the production method. The highest percentage of mislabelling and species substitution has been detected in open-air markets (65%) and small-scale retail shops (40%) compared with the big supermarket chains (10%). The high percentage of non-compliances with the European and Italian legislation highlights the need to improve the essential information demanded by consumers on fishery products marketed in open-air markets and small-scale retail shops. While there are laws in place, it is unclear how effective they are and what type of penalties food business operators of open-air markets and small-scale retail shops may incur.

Inaccuracy of Labeling and Visual Inspection for Microsporidian Parasites in Anglerfish Lophius litulon (Jordan, 1902) Collected from Chinese Retail Markets in Sardinia, Italy.

The aim of the present study was to evaluate the accuracy of labeling and the efficacy of visual inspection to detect the lesions by visible parasites in anglerfish Lophius litulon. One hundred samples were collected over a 2-year period (2011 to 2012) from Chinese retail markets in Sardinia, Italy. To assess the conformity of the items with the trade name, a preliminary visual inspection of the samples by a simple morphological analysis was performed. According to the Council Regulations (EC) 104/2000, 1224/2009, and 2074/2005, the Italian labels were examined to verify the appropriate indication of relevant information on traceability (trade name, scientific name, geographical area, and production method), and the samples of L. litulon were subjected to visual inspection to detect "visible parasites." Altogether, a high percentage of mismatching (70%) between the scientific name and trade name was pointed out. Moreover, 60% of the samples were visibly infected by Spraguea lophii, a microsporidian parasite of the nervous tissue that forms typical lesions (xenomas) in the fish flesh near the vertebral column. Although S. lophii is not pathogenic to humans, the presence of xenomas can decompose the fish flesh and render it unfit for human consumption. The high percentage of mislabeling, together with the inaccuracy in the visual inspection by Chinese food business operators highlighted the need to improve the European Union control system of fishery products imported from China and marketed in Europe.

Arsenic Speciation in Fish Products and Seafood as a Prerequisite for Proper Risk Assessment.

The Boi Cerbus lagoon, facing a mining and industrial site in Sardinia (Italy), is an important fishing area for the local population. Previous studies showed high concentrations of total arsenic (Astot) in fish, molluscs and crustaceans sampled in the lagoon, and a possible exceeding of the provisional tolerable weekly intake set by the Joint FAO/WHO Expert Committee on Food Additives by some local consumer groups. However, the percentage of inorganic As (Asinorg) should be known for a correct assessment of potential risk, as its toxicity is much higher than that of the organic forms. Eighty samples of 14 different species of fish, molluscs and crustaceans, sampled in the Boi Cerbus lagoon in 3 different seasons (winter, spring and summer), were analysed for Astot by inductively coupled plasma mass spectrometry (ICP-MS) and Asinorg by high performance liquid chromatography-ICP-MS. All the data obtained from the analysis were statistically processed to evaluate significant differences based on season, taxon and habitat, in preparation for a subsequent risk assessment.

Mercury occurrence in Italian seafood from the Mediterranean Sea and possible intake scenarios of the Italian coastal population.

Mercury (Hg) settlements in the Mediterranean Sea determine a potential toxicological relevance of seafood intakes for coastal populations. To assess this possibility, fish, molluscs, and crustaceans of commercial size of 69 different species were sampled and analyzed for total mercury (Hg(TOT)) from georeferenced areas and evaluated for their compliance with the European Union Maximum Residue Limits of 0.5 and 1.0 mg/kg wet weight (ww). Accounting for the weekly estimated seafood intake in the Italian coastal population (mean 469-626 g/person/week) it was then possible to recover threshold contamination values in seafood. Under a Tolerable Weekly Intake of 1.3 µg/kg/bw/week, a threshold seafood contamination <0.10 mg/kg ww has been derived for sensitive groups. A suitable algorithm based on the parallel MeHg and Hg(TOT) analysis on the most consumed species, helped to refine the uncertainties related to the conservative assumption in seafood all the Hg(TOT) present is in form of MeHg. This work aims to improve the link between the risk management and risk assessment strategies, with the identification of those fish and seafood species, that, when regularly consumed, could determine or prevent potential Hg(TOT)/MeHg overintakes in sensitive groups.