55 dead sharks on Pwll du beach, Gower, 'horrific'

16 July 2014 Last updated at 10:23

A marine biologist has described the "horrific" sight of 55 small sharks washed up on a Gower beach.

Judith Oakley believes the fish came to rest on Pwll Du beach because of bottom trawling.

The fishing method involves using a large net with heavy weights to drag the seafloor and everything that comes with it.

Ms Oakley said there were three different species on the beach which were spotted on Saturday.

"It was horrific," she said. "There are always grim reminders of why I am so passionate about marine wildlife and protecting it.

"I wandered around the beach in total disbelief. There were dead small sharks - smoothhounds and catsharks - strewn across the strandline, sand and amongst the rocks.

"I counted 55 and have never seen such a terrible image on a Gower shore, and such a tragic death for these incredible animals.

"The animals were all in very good condition and it was pretty obvious that this was a case of discards from bottom trawler bycatch. Even worse is that some of these species can live for up to 25 years."

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Bottom trawling causes long-term damage to sea bed

Bottom trawling causes long-term, deep-sea biological desertification of the sedimentary seabed ecosystems, and threatens their biodiversity scientists reveal.

A recent study focused on assessing the impact of trawling on the meiofauna (small organisms, between 30 and 500 micrometers) living in marine sediments in the fishing grounds of the continental slope, about 500m deep. The results reveal that trawling has led to meiofauna being 80 per cent less abundant in this area, and its biodiversity 50 per cent lower than similar areas where no trawling occurs.

Pere Puig, researcher at the ICM-CSIC who participated in the study said: "The dragging of the gear on the seabed lifts and removes fine particles of sediment, but it also resuspends small organisms living in the sediment that constitute the base of the food chain at these depths." He warns that if deep trawling continues at the same level, the seabed may end up becoming barren, “if the constant loss of superficial sediment endures over time".

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Bottom trawling: how to empty the seas in just 150 years

The government has refused to act against 'bottom trawling', which has turned Britain's seabed ecosystem into a wasteland

Robin McKie

The Observer, Sunday 9 February 2014

"I believe there is not a portion of the ground but what the trawl destroys," explained G Cormack, a fisherman from Torry, Aberdeen. "I have dragged 50 miles off Aberdeen. I have got fast there and brought up coral about 2.5ft in circumference, lumps of soft coral, and I am prepared to say that whatever is in the way of the trawler will not escape."

It is a stark description of the damage inflicted by "bottom trawling", the practice of dragging heavily weighted nets across the seafloor to sweep up fish – like cod and haddock – that thrive there. And it is all the more alarming for having been voiced almost 150 years ago. Cormack was giving evidence in 1866 to a royal commission on the impact of bottom trawling, which expanded massively in British waters from the beginning of the 19th century. Traditional fishers opposed bottom trawling, not just because they thought it damaged the seabed by ripping up coral, oyster beds and sponges, but because they believed it wiped out fish stocks. "Twenty years ago, we used to get 600 or 700 a head of fish a day," said another commission witness, B Simpson, a line-fisherman who worked off Spurn Point, Grimsby. "Now they cannot get above 20 head, or three or four score at the outside."

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Fishing Technique Flattens the Seafloor

Fishing fleets are altering the seafloor much like farmer's ploughs have altered the landscape, indicates a study of the effects of so-called bottom trawling on the continental slope off the Spanish Mediterranean coast.

Bottom trawlers drag nets and gear to capture fish, shrimp and other marine life along the seafloor, and previous research has called out this technique for stirring up sediment and destroying habitat.

This new study by a Spanish team looked down into deeper waters than typically studied, at the upper portion of the continental slope, which drops out toward the deep ocean and offers insight into how the deep-sea landscape changes.


Continued:  http://www.livescience.com/22937-trawling-smooths-seafloor.html