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Green Ormer Survey

Tagging an ormer

This blog gives you a glimpse into what it's like to participate in a Green Ormer survey with the AWT. Being a marine volunteer is more than just data collection; it's about resilience, consistency, and a shared commitment to conservation.

Recently, I had the chance to join an ormer survey with Mel Broadhurst-Allen, the AWT Living Seas Coordinator, and Lou Collings, an AWT marine volunteer. Here’s what I learned—and it’s pretty fascinating!

If you live in Alderney, you’ve probably heard of the Green Ormer (Haliotis tuberculata). This sea snail has an ear-shaped shell with a row of raised holes along the edge. The outer shell is mottled with green and brown hues, while the inner shell features a shimmering layer of mother-of-pearl. Its sturdy foot helps it cling to rocks and move around. 

Green ormer inner side

Green ormer inner side

Green Ormer

Green Ormer

Every three months, the Alderney Wildlife Trust (AWT) conducts a Green Ormer survey to monitor their populations and growth rate at key sites around the island. Each survey involves checking 100m² squares across various locations.

Getting Ready to Survey

Before heading out, we carefully checked the weather and tide times to ensure safe and smooth surveying conditions. Once on-site, our first task was to locate the specific square for the day using a GPS device. Following the GPS, we marked the square’s corners with brightly coloured buckets—such a clever and simple way to set boundaries!

Ormer squad

Ormer squad

Finding Ormers

Next, we were each assigned a path to avoid re-checking the same rocks, making the process efficient. Then, the real work began: turning over rocks to look for ormers.

Turning rocks

Turning rocks

Ormer with a tag

Ormer with a tag

When we found an ormer, the first step was to check if it had been tagged before. If it had, we measured it again to track its growth. If not, we measured its length and width using a calliper. Any ormer over 60 mm long got a new yellow tag with a character and a series of three numbers on it. The tag is attached to the shell carefully using non-toxic glue.

Measuring the length of an ormer

Measuring the length of an ormer

Lou was our go-to person for measurements and tagging—her small crossbody bag was packed with everything we needed: tags, glue, callipers, and a phone for recording the exact GPS coordinates and to take a photographic record once an ormer was measured. Once the data was logged (including square location, size, and any observations like sponges or parasites on the shell), we gently placed the rock back, making sure the ormer has a safe smooth return to its original position.

Tagging an ormer

Tagging an ormer

Why It Matters

These surveys contribute to a detailed database of Alderney’s Green Ormer populations, including their growth rates and overall health. Green Ormers hold significant cultural importance in Alderney and play a vital role in the ecosystem. These gastropods help control seaweed growth and serve as a crucial food source for whelks and seabirds.

Why It Matters These surveys contribute to a detailed database of Alderney’s Green Ormer populations, including their growth rates and overall health. Green Ormers hold significant cultural importance in Alderney and play a vital role in the ecosystem. These gastropods help control seaweed growth and serve as a crucial food source for whelks and seabirds.

An ormer clings - Thanh Doan

Why It Matters

These surveys contribute to a detailed database of Alderney’s Green Ormer populations, including their growth rates and overall health. Green Ormers hold significant cultural importance in Alderney and play a vital role in the ecosystem. These gastropods help control seaweed growth and serve as a crucial food source for whelks and seabirds.

Take a photographic record once an ormer was measured - Thanh Doan

Take a photographic record once an ormer was measured

While the survey process is straightforward, the real challenge is maintaining consistency. Regular monitoring is key to gathering meaningful data over time. If you’re passionate about Alderney’s marine life, why not join us? Whether it’s Green Ormer surveys, crab surveys, eelgrass walkovers, or seawater parameter surveys, there’s always an opportunity to get involved.

Please reach out to Mel at marine@alderneywildlife.org to find out more.

How many ormers can you find in this photo?

How many ormers can you find in this photo?

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