The economic theory of harvesting single-species systems is already well developed. The economic analysis of ecologically interdependent systems, however, is still in its infancy. Endogenizing a second species leads to quite complex model structures, which can only in part be resolved analytically. However, results can be derived that relativize certain views of single-species models. The paper discusses the economic utilization of ecological competitive systems in different settings of industrial organization (social optimum, open access, sole owner, monopoly). The central results are compared with each other and with the single-species model.