The case

Climate change is tough on small fishermen: it means they do not know how many fish there will be in the future – but, even worse, it makes them change their tactics so that fish stocks are even more likely to decline. The problem, the researcher says, is that the uncertainty due to climate change makes a fisherman less sensitive to the impact on his self-esteem of taking selfish actions like increasing fishing effort. That psychological component is ignored by traditional economics, which would have predicted that in the face of uncertainty, fishermen would have tried to reduce their risk exposure by fishing less. But involving actual small fishermen in a game introducing uncertainty in the fishing effort exposed what is really likely to happen, according to the researchers.

Fishermen participating in the decisions game. Photo and copyright: César Mantilla.
Fishermen participating in the decisions game. Photo and copyright: César Mantilla.

The above conclusion is the result of a study focusing on the choices made by small fishermen in Colombia. The conclusion, based on behavioral economics and a carefully-designed game that the fishermen played, is the opposite of what a traditional economic analysis would have predicted. Basically, the study shows that when environmental fluctuations happen, fishermen who as a result saw their economic fortunes fall take action to increase their fishing in future. Fishermen who saw their economic fortunes rise because of the environmental change just keep fishing as usual. The net result is that the probability of depleting the fishing stock increases - by a significant sixteen percent. The way to fight that tendency is to give small fishermen better, more comprehensible information on fish stock changes and finding ways for small fishermen to share the risk of environmental change so they do not need to change their tactics to their own detriment.

Game decisions

Scene from the decisions game. Photo and copyright: César Mantilla.
Scene from the decisions game. Photo and copyright: César Mantilla.

The researchers who embarked in this study collected the decisions from a game emulating the harvest of a shared fishing pond in a community of Colombian artisan fishermen. In this game fishermen got paid according to their decisions and their simulated harvest, as if they were fishing in real life. Each participant decided how many fishing trips to make by folding paper boats, knowing that each fishing trip granted a die roll indicating the harvest. Fishermen understood how their decision was part of a dilemma: a larger number of folded paper boats granted them a larger harvest, but decreased the available resource for the future. The economic shock was thus artificially “created” in the game throughout the die roll. An unexpectedly (low) high die outcome indicated a (dis)advantageous economic shock for the fishermen. Fishermen rolling the dice played on average for 6 rounds before depleting the fish pond; without the dice roll (i.e., each paper boat gave always the same harvest), the game lasted 7.5 rounds.

Read more about this project in: Mantilla, C. "Communication networks in common-pool resource games: Field experimental evidence," Journal of Economic Behavior & Organization 118 (October 2015): 215-26, doi: 10.1016/j.jebo.2015.06.003 (journal subscription required to read full article)

Authored by: César Mantilla, Assistant Professor at the Economics Department of Universidad del Rosario, Bogotá, Colombia, e-mail