AS the rivers and streams of Britain get ever cleaner the increase in the fish stocks grab the headlines.

Next in publicity list come the aquatic birds. But how much publicity do our mammals receive? The answer is not much.

Fortunately the Wildlife Trusts and Water UK have organised the "Otters and Rivers Project 1998-2001" but which also sets out to conserve the equally threatened water vole.

David Bellamy, the president of the Wildlife Trusts, writes: "More than 20 Wildlife Trust staff and any army of volunteers have built up a wealth of knowledge and experience in otter and wetland conservation and are ready and willing to meet the challenge ahead. To do this they will need the full and continuing support of the public, their partners in the water industry and the Government."

THE OTTER feeds almost entirely on fish and obviously high levels of pollution make life intolerable for this beautiful mammal. Prior to the industrial revolution the treat majority of Lancashire's rivers had large and healthy populations of otters.

Otters also have been around in Britain for a long time and fossils have been dated to the pliocene period (around 10 million years ago). By 1900 Lancashire's otters were almost extinct and it is still hard to imagine that these lovely creatures were once so common.

In the 1870s otters were still a feature of the river Irwell at Radcliffe near Bury.

"As through the wild country I rambled,

And live at extravagant rate,

On eels, chubs and gudgeons I feasted,

And fishermen all did me hate;

Yet still up the rivers I went

Where the fishes me stomach did cheer,

Till a challenge from Radcliffe they sent me

That they quickly would stop me career."

This proves that at one time there was widespread fishing and otter hunting almost up to the centre of the expanding settlement of Manchester.

The fish are thankfully on their way back, but it is not realistic to suggest that otters will return. Within 10 years they will become more common than is the case at the moment.

The WATER VOLE is one of our most ancient mammals and fossils have been found in the pleistocene geological age which takes it back as far as eight million years.

The scientific name for the water vole is arvicola terrestris which is very surprising.

Arvicola derives from the Latin arvum which means a ploughed field and colo which means "living in." Now we come to the word terrestris which means "of the ground."

While it is true to say that the water vole does burrow into the ground it always digs its way into river banks. Prior to 1835 this mammal was known as arvicola amphibian which seems to be a much more accurate name.

"Ratty" of Wind in the Willows is not actually a rat. It does not have a very long and hairless tail or a pointed nose like a rat but looks more like a domestic hamster.

Its diet is more than 90 per cent vegetable and is an excellent indicator of water quality as the water vole reacts adversely to high levels of pollution.

Water UK and the Wildlife Trusts are working very hard to give the otter and the water vole a chance not only to survive but to increase their range and population.