Decline in Wales' Otter Population Linked to River Pollution

For the first time in more than a decade, a national survey reports an unexpected decline in otter signs across Wales. After its rare success story and "remarkable comeback" in the 1970s, the latest survey serves as a "wake-up call" over the British country's river pollution.

According to research by Cardiff University and Natural Resources Wales (NRW), signs of otters - such as footprints, spraint (droppings) and holts (hiding places) - had declined substantively to 70% across the visited sites. That is down 22% since the last survey in 2010.

The otter population decline was described as a "wake-up call" about the state of the UK's rivers, BBC news reported. The first national survey suggests there had been fewer signs of the mammal on almost all waterways across Wales.

The university's researchers have published a number of articles and monographs in their website called the "Otter Project".

"Complacency" over the recovery of otter populations

 

(Photo : Photo by Sam Greenwood/Getty Images)
PONTE VEDRA BEACH, FLORIDA - MARCH 10: Two otters swim during a practice round prior to The PLAYERS Championship on The Stadium Course at TPC Sawgrass on March 10, 2020 in Ponte Vedra Beach, Florida.

UK otters were considered wiped-out in parts of the UK in the 1950s and 60s, however, had managed to recover in the 1970s.

Dr Eleanor Kean, an independent ecologist said in Natural Resources Wales, "a little bit of complacency" had developed in recent years about the otter's recovery - "often held up as a conservation success story", which is why the latest findings and ongoing monitoring involving a "big group of volunteers, naturalist and mammal groups" was so important, she said.

So far, results show that the worst affected regions were the Conwy, Loughor and Teifi rivers with smaller declines evident on most other catchments. Meanwhile, only a few seemed to have stable populations, such as the Severn.

"We're not back to situation we saw in the 70s but it is a warning to us that something may be going wrong," added Liz Halliwell, team leader for terrestrial ecosystems and species at NRW. As "top predator of our freshwaters" - an otter is an "important biological indicator of the health of rivers and wetlands," she explained.

A conservation specialist also added that if the decline continues to be widespread and sustained, it "could signal a much more insidious threat to the health of our river ecosystems."

Also read: Even Low Levels of Industrial Pollution Shortens Life Span of Older People

Reason for the declines

While it is early to tell, researchers have a few theories on the latest results. After a series of repeat surveys, they concluded that what they were seeing in the original data was correct.

An expert group set up by NRW to investigate said that the extent to which the so-called "forever chemicals" were accumulating in freshwater environments is concerning. This group of chemicals called PFASs, used in food wrappers, kitchenware and clothing to make them water and stain-free, had far greater impacts in the otter population decline.

"We are gathering more data on that at the moment including tissue analysis from dead otters, fish and crayfish in rivers," said Graham Scholey, conservation specialist at England's Environment Agency (EA).

According to a recent study, livers of otter carcasses from across England and Wales had PFASs in all 50 sampled. Experts linked the widespread of the chemicals in British waters to river and sewage pollution.

In the meantime, the impact of what the otters eat on their health and population numbers has not been determined.

Also read: Toxic 'Forever Chemicals' Found in British Otters Linked to Fatal Illnesses