Outdoors: '"Otters are great indicators of the health of our environment"'

It can perhaps best be reflected in a lack of angling prowess than any other reason, but the highlight of my recent season's fishing on the River Devon, Clackmannanshire, was not the capture of a glistening plump brownie but rather the sighting of a sleek free-swimming otter in a pool in one of the more remote parts of the river.

It was dusk in the early part of the season and as I waded upriver, repeatedly casting a trio of wet flies to search out the darker confines below overhanging branches, an otter suddenly appeared from behind a bend and swam straight towards me.

I froze with rod part-raised just as I was about to put in another cast. But rather than panicking, the otter simply altered its course and veered past me, its half submerged head glancing in my direction a couple of times.

I had seen coastal otters many times before in the Hebrides and Shetland, but this was my first ever river otter, which are always elusive and difficult to see.

This has especially been the case in central Scotland where for much of the 20th century industrial pollution, including contamination from organo-chlorine pesticides, had decimated the otter population in many areas.

However, in recent decades concerted moves to clean up our freshwater systems have resulted in a gradual increase in numbers and today virtually all of Scotland's rivers hold otters.

While this is good news, Grace Yoxon of the Skye-based International Otter Survival Fund, says it is important not to become complacent. She points out that although widely spread throughout Scotland, the number of individual animals is actually quite small, signalling an underlying fragility in status.

"It is estimated there are about 6,500 otters in Scotland, which is not a great number when you consider that this is significantly less than the human population of Skye," she says.

"It is hard for otters to quickly build up numbers because they are slow breeders. A mother otter will typically look after her two or three cubs for up to 15 months, which means she will not give birth every year.

"An otter only starts to breed after two years old and lives for about six years, making it a species with very limited capacity for population expansion."

The best chance of catching sight of an otter is on the west coast of Scotland and the Northern Isles. The coastlines of these areas hold rich pickings in the form of inter-tidal fish such as eelpout and butterfish, as well as crabs. Shore-living otters are often about during the day, making observation relatively easy.

The most reliable way to determine the presence of freshwater otters is to walk along the edge of a watercourse and if there are animals about, then it won't be long before you will find their tarry-black and sweet-smelling droppings or "spraints" conspicuously deposited atop a boulder or grassy mound. The spraints, which act as territorial and social markers, can also be found along the smallest of hill burns, for even here otters will seek out small trout in pools.

As well as fish, otters will occasionally take rodents, rabbits, frogs and waterfowl. Freshwater otters particularly favour eels and, according to Grace Yoxon, there is real concern that the dramatic decline in eel numbers in recent years may impact upon numbers.

"Otters eat a lot of eels and the eel population has crashed, so we are unsure what impact this may have," she says.

"Other threats include being run over by cars, and new housing developments by rivers. The accumulation in their bodies of heavy metals from pollution is still a problem in some areas.

"While it is encouraging that our environment has improved to bring otters back into certain areas, we still have a responsibility to protect them. Otters are great indicators of the health of our environment as they use both land and water habitats - both of which need to be in pristine condition for them to thrive."

This article was first published in The Scotsman, 13 November, 2010