Seafood is increasingly subject to traceability requirements set by importing countries and global buyers. These demands place significant pressure on value chain actors to change seafood production and trade practices to align to the standardized norms around legality and food safety. While processing companies are recognized as critical players in facilitating access to global markets there is currently a lack of understanding about how they respond to traceability demands. To address this gap, this paper employs a social practices perspective to analyse how and why the actual practices performed by tuna processing companies in Indonesia change in response to BRC certification and the EU IUU regulation catch certification requirements. The results demonstrate that responses are determined by the performance and embeddedness of existing social practices that make up tuna value chains. Furthermore, our findings showcase short term adaptive responses for practices within the direct control of processing companies while practices beyond the control of processing companies, for example those performed by middlemen and government officials, were more rigid and required new social and material arrangements to be developed. With traceability demands likely to expand, conceptualizing value chains as sets of interrelated social practices offers a novel way to understand the uptake of traceability demands.