The Big Seashell Survey is a large–scale citizen science initiative that mobilises the public to document seashell diversity along the North Sea coast.
Launched in 2018 by VLIZ (Flanders Marine Institute) and partners in Belgium, the Big Seashell Survey transforms a simple beach activity into structured biodiversity data. Each year, on a single coordinated survey day, thousands of volunteers collect, identify and record shells using a standardised protocol.
The project demonstrates how citizen science can deliver long–term ecological insights while raising ocean literacy among the public.
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Internationalisation
Since 2022 the event is also organized annually in The Netherlands by Naturalis and partners.
In 2023, CPIE joined and organized the event in 2 beaches in Northern France.
By the numbers
- Started
- Belgium: 2018
- The Netherlands: 2022
- France: 2023
- Editions: Annual, one–day survey in March
- Coverage: >400 km coastal area (Belgium 65 km + Netherlands 350 km + two cross–border beaches in France)
- Participants: ~3,500 in 2025
- Records: ~500,000 shells identified, 72 species (since 2018)
- Data platform: minka.vliz.be
Scientific and societal relevance
The Big Seashell Survey bridges the gap between research and public participation.
The data on seashells – a diverse and appealing group of marine fauna – contribute to understanding:
Species diversity and distribution of molluscs in the North Sea
Trends over time linked to climate, habitat and human pressure
Baseline monitoring for coastal ecosystem health
At the same time, the project provides a replicable model for inclusive, low–threshold field engagement. The Netherlands and France joined the initiative.
Method
The Big Seashell Survey applies a simple but standardised approach:
- Participants collect 100 shells in a predefined way on the beach.
- Shells are identified and counted together with an non–professional experts. Extra trainings are foreseen to increase data quality. Tools - pictorial protocol description, species identification card, reference collection – are provided to help public on–site to increase data quality.
- Data are entered via digital forms (minka.vliz.be) and validated by professional experts.
- Data (Belgium and France) can be consulted by minka.vliz.be
- Future aims: data publication (FAIR and open access) in repositories like EMODnet Biology & GBIF
Partnership and coordination
The Big Seashell Survey is coordinated by VLIZ, in collaboration with:
EOS Wetenschap, Natuurpunt, Province of West Flanders, Strandwerkgroep, Kusterfgoed, and the 10 Belgian coastal municipalities.
Cross-border editions are supported by partners in the Netherlands and France.
Press coverage & materials: available on request.
