A HUGE ancient fish trap more than 250 metres long and probably at least 1,000 years old has just been discovered in the Teifi estuary.

The underwater structure was first identified on aerial photographs and a recent exploratory dive at the site near Poppit has revealed the structure is protruding about 30 cm above the sand, allowing for a fuller investigation by divers.

A collaborative project is currently underway between Pembrokeshire College and the Dyfed Archaeological Trust, and members of the public are being asked to help with information for research into the conundrum of the ‘Poppit fish-trap’.

Dr Ziggy Otto, lecturer in the coastal zone and marine environment research unit at Pembrokeshire College, explained: "A large, underwater structure has been identified on aerial photographs and there can be little doubt that this rather impressive – and quite apparently man-made -structure is an ancient fish-trap.

"The structure is entirely underwater (at all stages of the tide); it has never been surveyed, but is approximately 260 metres long, and is possibly made of locally quarried rock, although use of boulders carried in during the last glaciation cannot be ruled out either.

"Its age is unknown, but because of its now entirely subtidal position, this fish-trap is very old, possibly dating back more than 1,000 years, when the sea level was lower and the entrance to the Teifi Estuary further towards the Poppit side."

He adds that the structure’s orientation precludes the possibility that it was designed to catch migratory fish, such as salmon and sea trout, going up the Teifi.

"The structure is a true conundrum, and certainly worthwhile investigating further, because it forms part of the historic and cultural seascape of the area."

The fish-trap can be viewed on Google Earth, north-west of the RNLI station at Poppit in front of the cliffs. If members of the public have any information, however anecdotal or minor, the investigators would like to hear from them.

Jen Jones, scientific diver and co-proprietor of the West Wales Diving School at Mathry, who undertook the first exploratory dive with Dr Otto, said: "This fish-trap is probably the oldest man-made structure in Wales ever to be scientifically investigated by way of scuba-diving."

She added that the section of the fish-trap dived is buried in the sand; it is about one metre wide and protruding about 30 cm above the sand. The rock boulders used in the construction of the fish-trap are encrusted with tube-dwelling worms, including the highly protected honeycomb worm (Sabellaria), a dense carpet of a variety of red algae species, with some sea anemones.

"This fish-trap has therefore metamorphosed from an entirely man-made structure to a naturally functioning reef, which adds to the biological diversity not only of the local area but also to that of the Cardigan Bay Special Area of Conservation as a whole," she said.

Louise Austin, head of heritage management at the Dyfed Archaeological Trust, said: "Fish-traps were a widely used means of catching fish in the past which made a significant contribution to the economy of many coastal and estuarine communities. Today only a few are known to survive in Wales. Recent aerial survey work has identified a handful of additional sites, such as the Poppit example, but there are few opportunities to investigate and record in detail these important underwater sites."

Further dives are now planned by Ziggy and Jen to complete a full underwater survey of the fish-trap.

Ziggy and Jen would like to express their gratitude to Paul Oakley (Cardigan Outboards), and Ray and Lynda Jordan for providing boat support for the dive.

If you have any information about this underwater structure contact Ziggy on z.otto@pembs.ac.uk or Jen on jenjones04@btinternet.com.