Social networks matter: Linking resource user's social behavior to coupled outcomes in a marine social-ecological system

Effectively managing the current and unprecedented level of anthropogenic impacts on the natural environment requires a clear understanding of the interrelationships between people (the social system) and nature (the ecological system). Yet we currently lack essential information on the pro-social behavior of resource users, and the ways in which their social relationships may influence system-level outcomes. In this dissertation, I draw on sociological and economic theories related to social organization and social capital to investigate resource user's social networks. I then examine their role in shaping environmental and economic outcomes in Hawaii's ethnically diverse, longline fishery as an example social-ecological system (SES).;I begin by adopting a network perspective to investigate the role of ethnic diversity and other stakeholder attributes on individual levels of social capital, measured by network prominence, opportunities for brokerage, and tie strength. Social capital is an important resource that can be mobilized for purposive action or competitive gain. The distribution of social capital in SESs can determine who is more productive at extracting ecological resources, and who emerges as influential in guiding their management, thereby empowering some, while disempowering others. I find that ethnicity plays a significant role in the distribution of social capital, while human capital and social capital are also positively related. Surprisingly, my results suggest formal leadership plays an insignificant role on social capital, suggesting fishery representatives and industry leaders are presently not effective channels for information flow and likely lack the ability to influence the opinions of others. In interpreting these results I argue that one minority ethnic group has succeeded in establishing a productive ethnic enclave driven by a turbulent period of settlement and resettlement as refugees. In contrast, I argue that a lack of basic social capital resources among another minority ethnic group with a less formidable history has decreased their ability to adapt to policy and environmental changes, leading to a breakdown in their participation in the fishery.;Next, I link data on fisher's social networks to detailed data on catch and effort over a period of five years to empirically estimate the relationship between information sharing relationships and rates of incidental catch (i.e., 'bycatch')---a pressing global environmental issue. The network exhibits strong homophily, with fishers organizing themselves into three information sharing network groups largely corresponding to ethnicity. Controlling for spatiotemporal factors, I find significant differences in shark bycatch among the three network groups. Moreover, bycatch rates for individuals whose majority of ties fall outside their ethnic group are more closely aligned with their network group, rather than their ethnic group. Significant differences in shark bycatch among network groups hold when controlling for spatiotemporal factors and vessel and operator specific variables known to effect shark bycatch. These results provide novel empirical evidence that network homophily is related to environmental outcomes, and indicate that social affiliations are tied to behaviors that can have a direct impact on ecosystems. I argue that the effect captured here relates to diffusion and strategic information sharing (or lack thereof) mediated by ethnic boundaries and social exclusion.;In my final essay, I link fisher's social network data to vessel cost-earnings data to econometrically evaluate the role of individual social capital on vessel economic performance. Social capital has proven to be a significant factor influencing economic outcomes in a variety of settings, yet there is little evidence of this effect in SESs. Many SESs are characterized by high levels of uncertainty and competition over limited resources, where the benefits of occupying advantageous structural positions in information sharing networks is likely enhanced. Controlling for common factors of production, I find that social capital in the form of local network prominence is positively related to economic productivity, while inter-ethnic ties as a measures of brokerage has a negative effect. I argue that social differentiation across ethnic groups inflated by high levels of competition causes actors that bridge ethnic divides to be penalized for associating with other groups, consistent with theories of social identity.;Taken together, this research contributes novel empirical evidence that contributes to the literature on social networks and social capital in SESs and among ethnically diverse populations. The primary takeaway is that social networks matter, and ethnic diversity plays a substantial role in mediating their effects on a diverse range of outcomes. These outcomes are relevant for achieving resource governance that is not only ecologically and economically sustainable, but also equitable.