Macro- and microelements in eel (Anguilla anguilla) from the northern regions of Poland

The abundance of the eel (Anguilla anguilla) in Europe has been on the decline in recent years, to the extent that this fish species is now considered to be threatened with extinction. Hence, the current implementation of the Eel Management Plan in Poland, whose aim is to restore w stocks of this fish. The main natural habitats of eel are the transitional waters of the Vistula and Szczecin lagoons and lakes in northern Poland. The eel is highly valued by many consumers for the taste and texture of its meat. The aim of the study was to determine differences in concentrations of macro- and microelements and toxic metals in muscles of the eel as a function of each specimen’s length, mass and the origin. The results of the study also served an evaluation of the health benefits and risks to consumers of eel meat with regard to the content of macro- and microelements and toxic metals. Specimens of the eel (Anguilla anguilla) were caught in 2011-2013, in five regions of Poland: the southern Baltic, inland lakes in northeast Poland, the Vistula and Szczecin lagoons, and in the Vistula River. The concentrations of Ca, P, Mg, Na, K, Fe, Sr, Zn and As were determined with optical emission spectrometry. The flameless atomic absorption spectrometry method was used to measure concentrations of Cu, Cd and Pb. The content of Hg and Se were determined with atomic absorption, those of mercury with cold vapour, and of selenium with hydride generation. The concentrations of macro- and microelements in most instances, with the exception of P and Zn, were negatively correlated with the eel’s length and mass, which indicated that small fish contained more minerals than large specimens. The eel is a rich source of phosphorus, zinc, selenium and iron, and it can supply significant quantities of the daily requirements of human consumers for these minerals. The other minerals occurred in eel muscle at levels that ranged from 2 to 6% of human daily requirements. Among the toxic metals, mercury was the cause for concern, while cadmium and lead occurred at low levels in all of the specimens examined regardless of their size. The mean concentration of mercury ranged from 0.147 to 0.273 mg kg-1 and was positively correlated with specimen length and mass. The content of mercury in large eel exceeded 0.500 mg kg-1, while small eel (up to 70 cm) contained lower levels of mercury. Large eel exceeding 70 cm can pose a threat to the consumer’s health because of mercury, and especially its organic from of methylmercury. This is why consumers should limit long-term consumption of larger eel, while it is safe to consume smaller specimens since they contain less mercury and more minerals than do large eel.