With increasing oil and gas activities in the Arctic, there is a risk that Arctic marine organisms will be exposed to petroleum related compounds such as produced water (PW) discharges. Hence, there is a need to investigate the potential biological effect s of PW to marine organisms and to implement and test new biomarker methodologies for their application in petroleum monitoring. The endocrine system, whose effectors are hormones, is essential for many regulations in an organism. Hence, the assessment of the reproductive function in organisms is essential in environmental monitoring due to its crucial role in the population fitness. The polar cod (Boreogadus saida) is a circumpolar gadoid fish which distribution overlaps with that of oil and gas activiti es in the Barents Sea and that has been shown as a suitabil sentinel species for petroleum monitoring in Arctic waters Based on the acquired knowledge of the host Institution (Akvaplan-niva) this project aims to (1) implement and validate new biomarker me thodologies focusing on the endocrine disrupting effects of petroleum related compounds in polar cod, (2) investigate the endocrine disrupting effects of chronic exposure of polar cod to PW and (3) develop a new in vitro assay for the detection of (anti) estrogenic activities of chemicals in polar cod liver explants culture. Herein, Akvaplan-niva proposes to host a young researcher originating from Le Havre University to trasnfer the scientific expertise developed on temperate fish to test and optimize an assay on an Arctic fish. In addition to scientific deliverables (publications, oral communication), this project will lead to long term relationship between both institutes.