Shell yeah! Cockle farming as alternative land use in salinized coastal lowlands − A case study on Texel, The Netherlands

Food security is increasingly threatened by overfishing, climate change, and environmental degradation. Over-fishing depletes fish stocks, while climate change disrupts ecosystems and reduces arable land in coastal regions through salinization. As seafood demand rises, sustainable alternatives are needed. This study explores land-based cultivation of the common cockle ( Cerastoderma edule ) as a potential climate-resilient land use in salinized lowlands. Experiments were conducted in a field laboratory in the reclaimed Polder Wassenaar (Texel, Dutch Wadden Sea), using semi-controlled raceways under four water-flushing regimes. Growth and survival of one-year-old natural Wadden Sea cockles were monitored over the 2023 growing season. Cockles grew primarily from April to June, with an average shell length increase of 7.0 ± 1.0 mm (25.5 ± 2.8 %) by September. Higher flushing rates enhanced growth during the algal spring bloom, while condition indices peaked in May and declined post-spawning. At lower flushing rates, the building up of spawning reserves was likely limited by insufficient food input. Survival averaged 21.3 ± 2.7 %, although one raceway suffered mass mortality, reducing overall profitability. Nevertheless, other raceways achieved economic returns comparable to conventional Dutch agriculture. The findings highlight survival rates as the most important factor for economic viability, requiring improvements in stock quality, seeding time, and stress reduction. With further system optimization and higher stocking densities, high-density cockle farming may provide a profitable and climate-resilient alternative for salinized coastal regions where traditional agriculture is declining. • Cockle aquaculture can be a sustainable profitable practice in salinized lowlands. • Cockle growth follows the algal spring bloom. • Increased flushing rates during algal bloom boost high-density cockle shell growth. • Further research is needed to enhance survival during cockle farming.