In the wake of increasing difficulties with producing enough food from land areas through the world, attention is being given to the sea as a source of food. Because the sea constitutes a common property resource, factor productivity is heavily influenced by technological externalities. The sea is also subjext to the spectre of Malthusian scarcity since man cannot manipulate the ocean environment (Barnett and More, 1963). We estimated the parameters using ordinary least squares of the dynamic Schaefer production model of the intervention of man into oceanic ecosystem. A second production model for the sea specifying diminishing returns to capital and labor for any fixed biomass was developed. The parameters of the latter model were estiamted by a computer search technique. The results indicate that the industry production function for marine life is subject to diminishing physical returns to capital and labor. For the cases considered in this study it also appears that the parabolic yield function developed by Schaefer, assuming constant returns to factors inputs, is not as realistic as a production function with diminishing returns to inputs with a given biomass.