In oyster production area the determination of the stock, estimation of mortality and growth rates are determinant for knowledge of the fishery. Growth models can be used to predict the time to reach marketable size (76 mm in Chesapeake Bay). They are also important in term of management, when they can predict the future value of the stock (Askew, 1978). Oyster growth models can be built by analysing growth of natural oysters but absolute age is orten unknown. Many authors report growth data in Chesapeake Bay for suspended oyster culture. Unfortunalely, modelisation of the growth was not developed. In that study oyster, shell growth models have been established at three stations in the Patuxent river. Seasonal eITects on growth were integrated in the model