The dead dogfish were spotted by holiday maker Colin Hill, who said that there were hundreds of them covering a 500-yard stretch of beach.
Colin said that the fish seemed not to have been dead for long, perhaps three days at the most.
The dogfish, part of the shark family, washed up on Saunderfoot Harbour Beach yesterday, Thursday, May 21.
Hundreds of dead dogfish were washed up along a 500 yard stretch of shoreline. (Image: Colin Hill)
It is not known what caused the mass death of the dogfish on Saundersfoot, but the most popular theory is that they were discarded bycatch from a fishing vessel.
Other explanations for such an event could be, discarded catch from anglers, storm and tide events washing ashore already dead fish or spring mortality and wash up.
The dead dogfish were all along the beach. (Image: Colin Hill)
The Saundersfoot incident is not an isolated one.
In 2019, dozens of small-spotted dogfish washed up at Burry Port, An experienced fisheries scientist later suggested the Burry Port dogfish were probably the result of clearing a beach set net, with dead fish dumped and then washed ashore on the next tide.
In 2021 hundreds of dogfish were found dead on Knap Pebble Beach in Barry, Vale of Glamorgan, with some still carrying hooks and tackle. Local environmentalists and the angling community blamed anglers who had caught dogfish incidentally while targeting other species and then left them on the beach.
Natural Resources Wales has previously described large strandings of small fish along Ceredigion and Gwynedd beaches as a ‘natural phenomenon’, where predator fish drive shoals into shallow water and calm seas and strong tides push them ashore. A similar tide effect could gather dogfish that have already died further offshore and raft them onto one stretch of beach.
A fourth possible explanation is that the dogfish died in deeper waters from routine natural causes before drifting ashore on certain wind and tide combinations.
It is not known at this time what caused the mass death. (Image: Colin Hill)
Local conservation expert, Cliff Benson who founded Sea Trust Wales conservation charity, said that such incidents on a smaller scale to Saundersfoot are not uncommon in Pembrokeshire.
“We quite often see dogfish or catsharks seemingly intent on suicide and beaching themselves, though nobody seems to know why,” said Cliff.
“However, this is on a different scale and looks like they might have been caught by some fishing boat that was hoping to catch more commercial species and thrown overboard dead.
“Another possibility is it’s a case of some marine pollution event, but [in that case] you would expect several species to fall victim not just dogfish.”
A spokesperson for Natural Resources Wales said:
“We investigated reports of dead fish at Saundersfoot and found no evidence of a pollution incident.
“The fish appear to be dogfish, and this is likely linked to fishing by-catch being discarded at sea.
“Tides have since cleared the majority from the shoreline and no wider environmental impacts were identified. We have informed the local authority and relevant partners.”