We investigate critical multi-level links between oceanographic change and equitable outcomes in the Mexican Humboldt squid fishery. The local fisheries authorities aim to increase economic benefits from the fishery through market interventions. Therefore we conceptualize empirically observed social-ecological dynamics at multiple levels in the squid fishery in a modeling framework to test these interventions (BEM+). We compare equity and fishery outcomes of our model to a standard bioeconomic model underlying decision making in fisheries management during oceanographic change (BEM). We consider the proposed market intervention and alternatives that explicitly account for multiple links between changing species dynamics and adaptive responses of squid fishers and squid traders. The predictions of the empirical model with multiple social-ecological links more accurately predicts observed fishery data compared to the standard bioeconomic model. Our empirical findings show that oceanographic variability leads to contradictory results for squid fishery livelihoods, during cold conditions squid fishers benefit from high catches but are trapped in a traders monopoly that fixes low prices. In contrast catch volumes reduce and competition increases during warming conditions. Our model analysis demonstrates that the implemented market interventions strengthen already severe economic equity of fishers. The market interventions need to account for the adaptive responses to oceanographic changes at trader and fisher level to maintain and strengthen equitable conditions in the fishery. We offer an example, how to operationalize this added complexity in a yet simple modeling framework, to guide situated policy design. Our model is one of the first implementations of a social-ecological model examined with local data to inform policy design.
