At Wageningen Marine Research I mainly work on shellfish stock assessments, and improving the techniques we are using. Annually, the stocks of commercially relevant bivalve species in Dutch coastal waters are assessed as a basis for fisheries management (e.g. to determine fisheries quota), commissioned by the Ministry of Economic Affairs and the Dutch Mussel producers' organisation (PO Mossel). Annually, we monitor shellfish stocks in the Dutch Wadden Sea, Delta waters (Oosterschelde and Westerschelde), and the Dutch coastal zone. We focus on the commercial species (mussel, cockle, Pacific oyster, Atlantic jack knife clam and cut trough shell) but register all bivalve species and some other benthic species as well. I lead these surveys, and carry out field work in the Wadden Sea and Delta waters. These surveys started in the early 1990s, which means we now have a dataset of about twenty years. This dataset forms the basis for a variety of studies including impact assessments and studies on ecological functioning, which I am involved in. Additonally, many shorter-term or more localized monitoring projects benefit from the annual shellfish stock assessments, since the sampling can easily be extended to additional locations, and the annual surveys provide shorter-term and more localized monitoring projects with ample reference data for the surrounding area and previous years. I enjoy knitting different monitoring projects together in order to maximize the efficiency (solving power vs costs). Every additional research project involving analysis of the long-term data set gives me the opportunity to learn more from all the data we have collected so far, and to get a better insight in what factors steer the population dynamics we observe. I also enjoy the practical side of this type of work: improving sampling gears, determining the efficiency of sampling gears, and getting my hands and feet dirty in the beautiful surroundings of the Dutch Wadden Sea and Delta waters.