The water vole is one of the key wildlife species in Wales at risk of disappearing altogether, according to conservation body WWF Cymru.
It says global threats to wildlife and habitats identified in the Living Planet Report 2018 are echoed in Wales.
The Welsh Government said it has set out its priorities for tackling the root causes of biodiversity decline, as the WWF called for politicians to “step up”.
Water vole numbers have declined by more than 90% since the 1970s, with the introduction of the North American mink – a predator – having a catastrophic effect.
At a Natural Resources Wales centre near Brecon, Powys there is a captive breeding programme, aimed at boosting the population.