The Evolution of the Maine Lobster V-Notch Practice: Cooperation in a Prisoner's Dilemma Game

Abstract

"The Maine lobster industry is experiencing record high catches because, in all probability, of an effective management program. One of the most important conservation measures is the V-notch program that allows fishermen to conserve proven breeding females by notching the tails of egg-bearing lobsters. Such marked lobsters may never be taken. Although thousands of lobster fishermen participate, it is a voluntary practice. The genesis of this practice is not easily explained, because V-notching poses a prisoners dilemma problem that gives fishermen an incentive to avoid the practice. The most common explanations for ways to overcome prisoners dilemma problems will not work in the case of the V-notch. An unusual combination of factors explains the V-notch program: (1) a strong belief among those in the industry that the V-notch is effective in conserving the lobster stock; (2) a low discount rate because the long-term gains from V-notching are higher than the one-time gain from defection; (3) a gain in reputation for those who V-notch. At the start of the 20th century, fishermen did not V-notch; by the end of the century, V-notching was common. We explain the change in strategies using a three-parameter evolutionary model that emphasizes the importance of culture change."