Social capital has been a key factor for co-management initiatives' success in small-scale fisheries. Nonetheless, this is a complex concept, which can be operationalized in different ways and has no specific standardized measures. This research explores Peruvian scallop aquaculture in the Sechura Bay of Peru as a case study, focusing on the development of social capital among fishers, enterprises and authorities. We evaluated social capital through three of its conceptual building components: (i) trust, (ii) collaboration and reciprocity, and (iii) common norms and sanctions. Specific indicators for each component were developed for analytical purposes. We conducted 66 surveys and 12 interviews with fishers and other key stakeholders. Based on our results, there is weak social capital among aquaculture fishers, enterprises and authorities in the Sechura Bay. This is evident through the low levels of trust and collaboration, as well as the lack of respect for common norms. Weak social capital may explain the two critical problems the system is currently facing for achieving sustainability: reduced availability of seeds and unfair agreements between enterprises and fishermen associations. Strengthening social ties and collaboration can increase aquaculture's resilience at Sechura Bay.