The supply of fresh fish is constrained both by limited natural resources—which are either unaffected or depleted by technological development— and by the face that the product is channeled through a limited number of established ports. Fishing fleets, furthermore, are fewer in number and easier to control than farmers. In the fruit and vegetable trade the sources of supply are both many and widely scattered, and transport routes and delivery points outside the wholesale market can multiply unobserved. The rapid increase in agricultural productivity and conservation techniques in the years since the war, as well as the improved efficiency of transport, accentuated these differences, making the produce trade virtually impossible to monopolize.

Diego Gambetta, The Sicilian Mafia The Busi…, loc. 559