Shellfishers’ Knowledge in Western Iberia: The Case Study of Edible Cockle (Cerastoderma Edule) In the Ria de Aveiro Lagoon

Abstract BackgroundCockles are an essential biological resource for several fishing villages in Europe, especially in Portugal. This bivalve is highly commercialized in the Aveiro coastal lagoon and has relevant socio-economic importance for local shellfishers. In the absence of a management plan, indications for carrying out new ecological studies on the cockle, and all the aggregated history of this natural resource in the Ria de Aveiro, sharing the ethnobiological knowledge of shellfishers becomes relevant in this scenario. We shared the highlights of local ecological knowledge (LEK) about the cockle (C. edule) in the Ria de Aveiro in favor of the adaptive management of this bioresource. MethodsRia de Aveiro is an ecologically prominent area in Europe due to its faunal biodiversity. Semi-structured interviews with sixty shellfishers in this coastal lagoon were carried out during April and May 2021. LEK data on the biology and ecology of the cockle (C. edule) were analyzed using an ethical-emic approach and the model of integration of different individual skills. These informal data were compared with previously published data for the species, the Fish Base, and GBIF databases. Interviews were categorized and analyzed using the Microsoft 365 MSO.Results and Discussion Five cockle capture tools were used in the traditional fishing of this bivalve in the Ria de Aveiro. The average minimum size of the cockle for capture was 23.4 mm, and the average capture per tide was 137.12 kg. The areas with the highest productivity and the most shellfish were RIAV1 and RIAV2. The habitat of the cockle is usually areas of sand and mud to an average depth of 2.71 cm. Feeds mainly small particles, plankton, mud, and algae. The main predators were crabs, European plaice, and bird species. Cockles spawn primarily in late spring and summer. As of 2010, there was a slight decrease in cockle stocks in the Ria de Aveiro due to overfishing, increased rainfall, and changes in the sediment. Shellfishers shared informal ecological and biological data often compared to previously published data for the species. Deeply considering and analyzing this knowledge is essential for a better understanding of the environmental context in the view of users of the natural resource in the Ria de Aveiro. ConclusionInformal data shared by shellfishers in the Ria de Aveiro were typical of filter-feeding bivalve mollusks. LEK may assist in planning future management plans for cockles, and unrefuted data may serve as untestable hypotheses. Understanding how fishers exploit the natural resource in the ecosystem can clarify and shape more adaptive socio-ecological actions. Ethnobiological studies in the Ria de Aveiro lagoon with other species may contribute to better management of this system since multiple fisheries are carried out in this coastal area.