Five different types of shark have been found in the River Mersey just decades after it was declared “biologically dead”.
The river was home to no more than 15 species of animals when surveys were done before building the Mersey Gateway Bridge in 2002 - thanks to industrial and sewage pollution.
But now more than 50 different species are expected in the next year in what has been called "the best environmental news story in Europe".
Mike Duddy from the Mersey Rivers Trust, said: “Over the last 30 years, there’s been this tremendous regeneration, this renewal of the River Mersey that started slowly but is now picking up pace.
"I still think we’re right at the beginning of something special.”
The findings come after 37 different species of fish were caught by anglers in 2022, nearly two and a half times the number of species found in 2002.
As well as huge eels, sea scorpions and restaurant delicacies like turbot, scientists believe there may even be rare smelt now breeding in the estuary.
This is expected to be a boost for the environment across the whole region right into North Wales.
Humpback whales were spotted off the coast of Liverpool in 2015 for the first time since 1938 but in the Mersey itself, there have also been otters, octopus, salmon, seals and even porpoises.
Alex Campbell, from Seacombe, has been fishing since he was eight.
He said: “When I was a kid, it was just common eels and flounders which are pretty pollution tolerant.
“Then we started picking up cod and other types of fish in the water. We’re now getting what I call ‘holiday species’."
Mike added: “It’s the best environmental good news story in Europe without a doubt.
"Everywhere else nature is in decline but in the Mersey the wildlife-ometer is in the red and it’s got loads and loads to go.
"It’s full steam ahead. David Attenborough talks about an environmental crisis but the Mersey is not."
But despite the welcomed biological renewal on the River Mersey, the issue of rubbish is still a major problem.
Mike said: “This is part of the ongoing issues with the Mersey. Instead of catching fish, we’re catching wet wipes and masks.
“We’ve come on a journey where Liverpool had no waste water treatment works but now it does.
“United Utilities have improved wastewater treatment across the north of England. That’s why our rivers are full of fish but we’re only part way there.”
Many are calling for them to invest more money into improving infrastructure.
A United Utilities spokesperson said: “We’re proud to have been a key partner in the Mersey Basin Campaign and since 1991 we have invested around £3bn… we’re pleased that our investment has had a positive impact with the wide variety of aquatic life that continues to return to the Mersey.
“We agree that there is more to be done though and that’s why last year we launched our Better Rivers: Better Northwest campaign.”
This campaign will invest £230 million to improve the waterways by reducing overflow spills and will continue with greater investment from 2025 onwards.
Mike and his group are making a list of all the species they catch which the Rivers Trust will then take to councils and government organisations like Natural England.
Cllr Liz Grey, who heads up Wirral’s environment committee said: “This is really good news that more species and rare ones are being found there. We’ve come such a long way from the awful polluted mess it was becoming when I was young.
“However we’ve got to be vigilant and protect all those species and ourselves from any pollution, especially plastics. That is the responsibility of everyone using the river right from its source to the mouth.”