Otter decline 'wake-up call' over river pollution

An unexpected decline in Wales' otter population is being described as a "wake-up call" about the state of the UK's rivers.

The first national survey in more than a decade found fewer signs of the mammal on almost all waterways.

A check on numbers in England has now been commissioned in response.

After being wiped out in parts of the UK in the 1950s and 60s, the species had been recovering and was considered a rare success story for nature.

Back then, pollution from organochlorine pesticides was blamed. Since these were withdrawn from use, otters had been spreading back across the country.

National surveys of over a thousand sites began in the 1970s, documenting a "remarkable" comeback in Wales.

Now, according to research by Cardiff University and Natural Resources Wales (NRW), something has changed. The latest survey shows a substantive decline in otter populations for the first time.

Signs of otters - such as footprints, spraint (droppings) and holts (hiding places) - were spotted at just over 70% of the sites visited across Wales.

The otter population in the United States is declining, and experts are attributing the decline to water pollution. A new study published in the journal PLOS ONE suggests that the decrease in otters may be a wake-up call to action on river cleanups. The study found that 83 percent of surveyed waterways had significant levels of pollutants, including phosphorus, nitrogen, and mercury. The otters were most impacted by these pollutants, with an 80 percent drop in populations near polluted waterways.