The introduction of the tonaira and sardinal nets transformed medieval and early modern fisheries, notably impacting the salted fish proto-industry. These techniques reveal a dynamic centre-periphery model in fishing: MarseilleMarseille and ProvenceProvence as the technological core, and CataloniaCatalonia as a periphery with multiple interconnected nodes. This also highlights the paths of technological transfers in the preindustrial era. The tonaira, originating from ProvenceProvence or LanguedocLanguedoc, marked a significant shift in preindustrial fisheries, challenging traditional practices. It was first introduced to the coast of GironaGirona and the city of TortosaTortosa, a key commercial hub. Skilled fishermen, particularly from the region of la SelvaSelva, La, mastered this technique and spread the new tackle southwards. The sardinal, similarly introduced by Provençal fishermen in Girona’s productive waters, spurred legal conflicts and signalled the rise of proto-industrial fisheries. The diffusion of these technologies underscores a centre-periphery dynamic: innovations spread from the specialized northern centres, such as MarseilleMarseille, to the Catalan periphery, with Girona’s coastal villages emerging as a pivotal node, adapting and transmitting these advancements thanks to the migration of skilled workers. The interplay of fishermen migrations and institutional support, including direct investment by the city council of Tortosa, reveals the complex nature of this technological diffusion. Girona’s advantageous geography, proximity to Provence, and specialised fishing community solidified its role as Catalonia’s primary halieutic centre in the fifteenth and sixteenth centuries.