The Role of Catch Portfolios in Characterizing Species' Economic Linkages and Fishers' Responses to Climate Change Impacts

The collective harvest behavior of fishers, as revealed by their catch portfolios, gives rise to an economic linkage among targeted species. Mapping the economic connectivity among species helps identify species that may play a role in fishers' adaptive capacity to climate change impacts. In this study, we used survey data and network analysis to map the connectivity among species harvested by small-scale Galician fishers holding the same set of fishing permits. We characterized species by describing their roles in the system of connected species via four network centrality measures: degree, closeness, betweenness, and eigenvector. We used connectivity metrics in a discrete choice framework to evaluate the relation between species roles and fishers' species choices under a hypothetical climate change impact. In particular, we asked the following question: Which species are likely to be added to a catch portfolio in response to a climate-driven negative impact on fishing returns? Galician fishers responded to hypothetical scenarios by adding species not central to the network and species that are likely to be located within clusters in the network and by diversifying their portfolios of permits. Our work suggests that species connectivity due to fishers' behavior deserves serious consideration for practitioners who seek to improve institutional arrangements that promote the resilience of small-scale fisheries.