Traditional economics has always had problems dealing with externalities -- costs or benefits that are not included in the price for a good or service. A tree has "no value" economically unless it is turned into board feet and a tuna has none either unless it is turned into sushi. The price for the wood or the fish fillet does not include the services the two biological resources provide: hydrological and erosion control in the case of forests and ecosystem stability in the case of large ...