Native salmon have returned to the Thames after almost 200 years, with experts hoping the fingerlings released yesterday will be the start of a breeding population filling the river in under a decade.

The young salmon were released in to Thames tributary the Lambourne River in Newbury but they are expected to move downstream to parts of southwest London over the next year.

Thames salmon died out in the 1830s.

But with the river gradually getting cleaner, other types of salmon that do not breed in the Thames moved in from 1974, and now the Environment Agency says the river is clean enough for its own breeding population.

The agency's Darryl Clifton-Dey said the new salmon were expected to stay in the river for a year before heading downstream through London then up to Greenland before returning to breed.

"People do fish for salmon on the Thames but the population is so small at the moment that there's not a great deal of chance of catching one.

"Hopefully if these come back, and if they breed and if the young from those come back, then in a few year's time there'll be quite a few salmon around."

About 5,000 salmon eggs were incubated to become 0.8in baby fish that were introduced in to the river.