In France, the sampling strategy for the official monitoring of lipophilic phycotoxins in bivalve shellfish relies on the definition of risk areas and high risk periods, during which a systematic weekly analysis of toxins in shellfish is performed. Since 2010, high risk periods are defined as follows: the occurrence of one result above the European regulatory limit (160 μg equivalent okadaic acid/kg shellfish) over the last 3 years leads to that month being considered a high risk period. This definition was established according to a statistical analysis of the official monitoring results for the period 2003-2008, based on the mouse bioassay (MBA) as the official analytical method. As of the 1st January 2010, the MBA has been replaced by LC-MS/MS. In 2014, a new statistical analysis was performed, based this time on results for the period 2010-2013 for which quantitative LC-MS/MS data are available. We tested the robustness of the definition set in 2010 and identified a new methodology to improve our sampling strategy for lipophilic toxins in bivalve shellfish, based on Bayesian inference.