Natural populations are affected by a range of factors, including climate and contaminants. In this study, we have used use data from both population monitoring as well as contaminant monitoring to analyse variation in abundance of Atlantic cod on the coast of Skagerrak and black-legged kittiwake in mainland Norway. For Atlantic cod, we found significant effects of both climate (temperature and wind) as well as contaminants (concentrations of HCH-A, HCB and PCB-153 in blue mussels). For black-legged kittiwake, a population model confirms that for the southerly populations Runde and Sklinna, either adult survival is lower than in more northerly populations, or that chicken mortality is extremely high (~95%)
