A rare caviar-producing fish has caused a splutter after being caught in the River Thames at Greenhithe.

Anglers and commercial fishermen were alerted when it was confirmed on Monday that a 10lb Siberian sturgeon had been caught.

It is the second time in three months the species, which produces expensive caviar, has been found in British waters.

The first was 200 miles away near Pembroke Dock, South Wales, and that was the first one reported in Britain since 2004.

After being quickly weighed and photographed, it was put back in the water unharmed by Greenhithe angler Peter Johnson, who caught it on lugworm bait.

It was caught on November 2, but was not revealed until Monday when the fish had been positively identified from photographs by experts at the National Research Institute of Science and Technology for Environment and Agriculture.

Just 1lb of the caviar sourced from the Siberian sturgeon costs in the region of £630.

Steve Colclough, chairman of the Institute of Fisheries Management (IFM) marine specialist section, said the fish could possibly be one lost from cages in the Gironde river in France several years ago during a caviar farming experiment - but was more likely an escapee from the UK pet trade.

Anyone catching a sturgeon should take a photo, measure it and then release back into the water unharmed, he added.

They should then contact the Inshore Fisheries and Conservation Authority or Cefas at Lowestoft on 01502 562 244.

Mr Colclough would also like to hear from anyone who catches a sturgeon at srcifm@gmail.com or 01634 327899.

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