A tragedy of the commons case study: modeling the fishers king crab system in Southern Chile

ZAMBRANO, ALAN; LAGUNA, MARÍA F.; KUPERMAN, MARCELO N.; LATERRA, PEDRO; MONJEAU, JORGE A.; NAHUELHUAL, LAURA

PeerJ

PeerJ

Año: 2023 vol. 11

Illegal fishing in small-scale fisheries is a contentious issue and resists a straightforwardinterpretation. Particularly, there is little knowledge regarding cooperative interactionsbetween legal and illegal fishers and the potential effects on fisheries arising from theseinteractions. Taking the Chilean king crab (Lithodes santolla; common name centolla)fishery as a case study, our goal is twofold: (i) to model the effect of illegal-legal fishers’interactions on the fishery and (ii) analyze how management and social behavioraffect fishery’s outcomes. We framed the analysis of this problem within game theorycombined with network theory to represent the architecture of competitive interactions.The fishers’ system was set to include registered (legal) fishers and unregistered (illegal)fishers. In the presence of unregistered fishers, legal fishers may decide to cooperate(ignoring the presence of illegal fishers) or defect, which involves becoming a ‘‘superfisher’’ and whitewashing the captures of illegal fishers for a gain. The utility of bothplayers, standard fisher and super fisher depend on the strategy chosen by each of them,as well as on the presence of illegal fishers. The nodes of the network represent the legalfishers (both standard and super fishers) and the links between nodes indicate thatthese fishers compete for the resource, assumed to be finite and evenly distributed acrossspace. The decision to change (or not) the adopted strategy is modeled considering thatfishers are subjected to variable levels of temptation to whitewash the illegal capture andto social pressure to stop doing so. To represent the vital dynamics of the king crab,we propose a model that includes the Allee effect and a term accounting for the crabextraction. We found that the super fisher strategy leads to the decrease of the kingcrab population under a critical threshold as postulated in the tragedy of the commonshypothesis when there are: (i) high net extraction rates of the network composed ofnon-competing standard fishers, (ii) high values of the extent of the fishing season, and(iii) high density of illegal fishers. The results suggest that even in the presence of superfishers and illegal fishers, the choice of properly distributed fishing/closure cycles orsetting an extraction limit per vessel can prevent the king crab population from fallingbelow a critical threshold. This finding, although controversial, reflects the reality ofHow to cite this article Zambrano A, Laguna MF, Kuperman MN, Laterra P, Monjeau JA, Nahuelhual L. 2023. A tragedy of the commons case study: modeling the fishers king crab system in Southern Chile this fishery that, for decades, has operated under a dynamic in which whitewashing andsuper fishers have become well established within the system.