Enlarging the shadow of the future: avoiding conflict and conserving fish

Abstract

Conflict of interest among fishers characterizes most fisheries and leads to competition for the resource. This puts a premium on present actions and discounts the future. As a result, most common-property fisheries inexorably move toward overexploitation. It is proposed here that the iterated prisoner’s dilemma (PD) captures the essence of the conflict between present actions and the need for conservation. The iterated PD is outlined and the ‘tit-for-tat’ (TFT) strategy is explained. This proposes that players should cooperate on the first move and then do whatever the other player did on the previous move. It has been shown in computer tournaments that TFT is most often the highest score in the iterated PD, even though it does not win every time. To illustrate how the iterated PD may serve as a model for fisheries, it is used to interpret the interactions of crabbers, trawlers and scallopers on the inshore trawling grounds of south Devon, UK. Mobile and fixed gears are separated in the inshore ground by voluntary partitioning arrangements called the Devon management system. Certain areas are reserved for crabbing only; the crabbers tend to live in small communities, and are related to one another. Small trawlers are also from local communities, but larger beam trawlers and scallopers, although based in south Devon ports, fish all around the UK. It is proposed that these differences in social and genetic structure predispose crabbers and small trawlers to respect the regulations of the partitioning agreement, whilst the larger vessels are more likely to break the agreement when it suits them.

In all of man’s written record there has been a preoccupation with conflict of interest; possibly only the topics of god, love and inner struggle have received comparable attention.

Luce and Raiffa (1957)