Search

Highlights: [•] Highest concentration of Hg was not found in the central part but in the northern part of the North Sea. [•] The Hg concentrations in coastal and fjord cod increased southward along the coast. [•] Only three samples out of some 1200 cod muscle showed Hg concentration higher than 0.5mgkg−1, the EU limit for foodstuffs. [•] Cd concentrations in liver of coastal and fjord cod increased northward along the coast. [Copyright &y& Elsevier]

Abstract: Seasonality of otolith zone formation can vary between fish species, and between populations within the same species. Although information on otolith zone formation is important for fish age estimation, there is incomplete knowledge of factors influencing variation in otolith opacity. In this study, marginal increment types (opaque or translucent) of two spatially distinct Atlantic cod stocks were assessed. Cod otoliths from the southern North Sea, where the fish experience high temperatures were compared with cod otoliths from the Barents Sea, where the fish experience much lower temperatures. There was approximately a shift of 5 months for deposition of translucent otolith material between the two areas. Cod from the southern North Sea deposited translucent otolith material in the period July–November, while it occurred in the period December–April in the Barents Sea. Inter-annual differences within areas were minor compared to differences between the two areas. [Copyright &y& Elsevier]