Social networks and environmental outcomes

Significance Understanding how social dynamics drive outcomes in environmental systems is critical to advancing global sustainability. We link comprehensive data on fishers’ information-sharing networks and observed fishing behaviors to demonstrate that social networks are tied to actions that can directly impact ecological health. Specifically, we find evidence that the propensity for individuals to share information primarily with others most similar to themselves creates segregated networks that impede the diffusion of sustainable behaviors—behaviors that could have mitigated the incidental catch of over 46,000 sharks in a single commercial fishery between 2008 and 2012. Our results suggest having a better understanding of social structures and bolstering effective communication across segregated networks has the potential to contribute toward more sustainable environmental outcomes. Social networks can profoundly affect human behavior, which is the primary force driving environmental change. However, empirical evidence linking microlevel social interactions to large-scale environmental outcomes has remained scarce. Here, we leverage comprehensive data on information-sharing networks among large-scale commercial tuna fishers to examine how social networks relate to shark bycatch, a global environmental issue. We demonstrate that the tendency for fishers to primarily share information within their ethnic group creates segregated networks that are strongly correlated with shark bycatch. However, some fishers share information across ethnic lines, and examinations of their bycatch rates show that network contacts are more strongly related to fishing behaviors than ethnicity. Our findings indicate that social networks are tied to actions that can directly impact marine ecosystems, and that biases toward within-group ties may impede the diffusion of sustainable behaviors. Importantly, our analysis suggests that enhanced communication channels across segregated fisher groups could have prevented the incidental catch of over 46,000 sharks between 2008 and 2012 in a single commercial fishery.