In 2006 and 2007, 35 fish samples from the Somme River and its tributaries were analyzed to measure their concentrations of dioxins, furans, and dioxin-like polychlorinated biphenyls. Interpretation of these data is limited by the small number of samples and the lack of information on the composition of the samples. Exceedances of standards are therefore sometimes difficult to assess and have led to "precautionary" bans. The study provides local authorities with the technical elements of a sampling protocol to be implemented to yield results sufficiently precise to aid decision-making. It was developed by integrating local data and involving local stakeholders (fishing federations, government agencies, professional fishermen, etc.). Ultimately, six sites on the Somme River and three on its tributaries are proposed. Five fish species have been selected. Other elements of the sampling plan are also addressed: number of composite samples, number of fish per composite sample, sampling period and method, pollutants to be measured, and sample preparation. (R.A.)