The Shark Trust’s Great Eggcase Hunt
Project Overview:
SeaKeepers is supporting the Shark Trust’s longest-running flagship initiative: the Great Eggcase Hunt. This global citizen science project invites beachgoers, divers, and snorkelers to search for and report shark and skate eggcases (also known as mermaid’s purses) either washed ashore or observed still developing underwater. Participants can search the shoreline specifically for eggcases or can keep an eye out when joining a SeaKeepers’ shoreline cleanup!
Participants follow four key steps:
- SEARCH the strandline or underwater habitats for eggcases
- IDENTIFY finds using the Great Eggcase Hunt identification resources
- RECORD details via the online recording form or citizen science app
- DISCOVER how your finds build a bigger picture through the online results maps!
Program Partners
- Shark Trust
Location
- Global
Expected Time Frame
- Ongoing
Citizen Science activity parameters listed above are flexible and negotiable.
Background:
The Great Eggcase Hunt began in 2003 with a single discovery on a beach in Devon, UK. Since then, it has grown into an international movement, collecting over half a million eggcase records, with nearly 50,000 submitted in 2024 alone.
Approximately 44% of shark, ray, and chimaera species lay eggs encased in tough, leathery capsules. Once hatched, the empty cases may wash ashore, where each species’ unique shape and features allow identification.
By recording empty eggcases found washed up on beaches, or observing those seen still developing in the wild by divers and snorkelers, participants help pinpoint egg-laying grounds, providing valuable ecological data.
The Shark Trust has expanded the project globally with regional ID guides available in the UK, across much of Europe and the Mediterranean, the USA (Atlantic and Pacific coasts), Gulf of Mexico, and Australia. Materials are translated in languages including Spanish, Dutch, Greek, Turkish, Arabic, and Hebrew.
Mission:
Originally launched to raise public awareness of elasmobranch diversity in British waters, the Great Eggcase Hunt has become a powerful educational and conservation tool. It builds local ecological knowledge, strengthens community engagement, and promotes skill development in species identification.
By reporting eggcase finds, participants help researchers understand where and when oviparous species are laying eggs and which habitats they prefer. Underwater sightings can also link to beach findings, creating a fuller picture of elasmobranch reproduction.
Data Impact:
Great Eggcase Hunt data have been submitted to processes including marine planning, Environmental Impact Assessments, and the IUCN Important Shark and Ray Areas (ISRAs) project.
The Shark Trust is currently standardizing datasets to make them open access, increasing their value for conservation science worldwide.
Relevant/Previous Scientific Publication(s):
How to Participate:
To join The Great Eggcase Hunt, please email SeaKeepers’ Citizen Science Manager at rosemarie@seakeepers.org.
Program Partners:
Get Involved
If you’re interested in learning more about this specific program opportunity, please reach out to our team below to find out more about this program or get involved in other opportunities with SeaKeepers.
Explore More Opportunities
At-Sea Opportunities
Citizen Science Opportunities
Education Opportunities
