A critically-endangered fish - which can grow up to 20ft in length - could eventually start to swim in Norfolk rivers again.
Sturgeon were once common in large lowland rivers around the UK, including the Ouse in west Norfolk.
But the fish, which live up to 100 years, were driven to the point of extinction centuries ago by over-fishing, the building of barriers like weirs and sluices, and pollution.
Now, breeding projects in France and Germany have led to the so-called "dinosaur fish" - which date back to the Jurassic period and survived the demise of the dinosaurs and other mass extinctions - starting to return to the sea off the south coast of England.
And it is hoped their resurgence there may ultimately lead to them returning to their former habitats - including the Ouse, Severn and Thames.
Sturgeon return to rivers in the summer months to spawn before disappearing back to sea where they feed on bottom-dwelling species such as worms and mussels.
The UK Sturgeon Alliance is attempting to reverse the decline of the migratory fish and bring it back to UK waters. It is appealing for people to report sightings.
A Save the Sturgeon website aims to raise awareness of the fish and allows users to log records of spotting the fish, which will be fed into a database to help the alliance understand its current presence.
The alliance is formed of the Zoological Society of London, Blue Marine Foundation, Institute of Fisheries Management and the Severn Rivers Trust.
Alex Hubberstey, project co-ordinator from the Blue Marine Foundation, said: "Sturgeon have survived multiple mass extinctions, but humans have driven these extraordinary fish to the brink of total disappearance.
"My hope is that sturgeon will once again be a regular sight in our rivers and coasts."
Sturgeon were considered such good eating that they were dubbed Royal fish - meaning any caught must first be offered to the monarch before being sold or disposed of.
The last recorded UK sturgeon was found in the River Tywi, in Carmarthenshire, in 1993.
People can find out more about sturgeon or record sightings at savethesturgeon.com
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here