Thread by @OwsWills

For a millennium it lay unseen and undisturbed, a stone's throw from one of Wales' most beautiful beaches.

But in 2007, an aerial survey revealed something astonishing just beneath the waves.

A brutally effective, colossal coastal hunting ground…

THREAD 👇

Stretching more than 276m (905ft) along the Pembrokeshire seabed, the gigantic V-shaped stone structure at Poppit Sands was used to catch fish without the need for a boat or rod.

Built during the Norman Conquest, it may have fed the Tironensian Monks at nearby St Dogmaels.

Catching fish in rivers, lakes and tidal waters using traps or weirs is an ancient practice.

Coastal traps work by trapping fish behind a barrier as the tide goes out.
Such traps are often V-shaped, and at the tip of the 'V' is a sluice - where fish are moved into a net or trap.

Fish traps were a highly controversial topic 1,000 years ago.

They were so ferociously efficient at catching fish that their use in inland rivers was banned in the Magna Carta, only being permitted on the coast.

Due to its now entirely sub-tidal position, archeologists believe that the Poppit Sands fish trap is very old, dating back to a time when the sea level was lower and the entrance to the Teifi Estuary was further towards the Poppit side.

Fortunately for 21st century fish, despite the trap's enormous size, the fact that it is rarely more than partially uncovered even at the lowest tide means that fish are no longer caught.

Ironically, the boulders used to build the trap have since become a naturally effective net of sorts – becoming home to the highly protected honeycomb worm (Sabellaria), and a dense carpet of red algae species and sea anemones.

Despite being discovered in a flypast by the Royal Commission on the Ancient and Historical Monuments of Wales, it could easily have been found on Google Earth!

More 👉

🐟 walesonline.co.uk/news/wales-new…
🌊 dailymail.co.uk/sciencetech/ar…
🎣 coflein.gov.uk/en/site/24568/…
🛶 cardigan-stdogmaels.co.uk/ancient-fish-t…

This thread is part of a wider collection on the many Secrets of Wales, spanning 220 million years 👉
bit.ly/SecretsOfWales

The Royal Commission on the Ancient and Historical Monuments of Wales sent me this incredible coastal fish trap/weir mapping app - listing and expanding upon all known examples in Wales 👉
coflein.gov.uk/en/site/search…