BACK in August I wrote in this column about Atlantic salmon “sniffing” their way back up the rivers of Ryedale on their spawning migration.

The recent return of the once extinct salmon to Ryedale’s waterways has been a success story to cheer about, but there is another local fish whose fortunes are going in the opposite direction.

I was reminded of the fact recently while walking along the banks of the River Derwent at Old Malton, just upstream of St Mary’s Priory.

I was chatting to an angler who was trying to catch himself one of the grayling that this stretch is famous for, when the end of his rod jumped and he wound in a healthy looking eel of about 2ft long.

After an entertaining and slippery battle to remove the hook, with the eel wrapped around the fisherman’s arm, the beautiful animal was popped into his keep net.

Eels are very unusual members of their family, so much so that many people are unaware that they are fish at all – even the Environment Agency refers to, “… a lamprey, fish and eel pass…”, on the River Derwent at Howsham.

This isn’t surprising really considering their long, snake-like bodies, lack of any large fins and smooth, slimy skin devoid of fish-scales.

What’s more, as long as their body remains moist from rain or wet grass, they possess the very un-fishlike ability to travel across land by wriggling like a snake – a skill which enables them to colonise ponds with no in or outflow streams.

Even stranger than their physical appearance is the European eel’s life-cycle which, like its fortunes, is diametrically opposite to that of the salmon.

Eels migrate from sea to rivers and back again, but unlike salmon and sea trout they are born in the sea and spend most of their adult life in inland waterways.

The most astonishing part of the story is the distance involved.

Every mature adult eel in Europe makes one gargantuan swan-song of a journey, down its local river to the sea then right across the Atlantic Ocean to a small part of the Caribbean called the Sargasso Sea, where mating and egg-laying take place.

After hatching, the tiny baby eels don’t actively swim the 3,000 miles back home, but just float around and let the Gulf Stream take them there – a journey that can take three years to complete.

By the time they arrive at our shores in their millions they have grown to about three inches long and are known as glass eels due to the transparency of their bodies.

Now, you may be wondering: “If millions of baby eels are managing to reach river estuaries like the Severn and Humber then what is the problem?”

The answer is that it shouldn’t be millions – it should be trillions.

The truth is that in the last 30 years eel numbers have dropped by 95 per cent, and that’s not just in the UK but over the whole of Europe.

What is all the more worrying is that scientists don’t really know the reason for this catastrophic population crash.

It could be something hindering the adults on their long journey west (PCB pollution and nematode parasite disease have both been suggested) something killing the larvae as they float back east or a combination of the two.

One thing is certain – the problem is not water quality in Britain because our rivers are as clean as they have been for a long time.

We can do our little bit to help in Yorkshire though, by making our rivers as eel-friendly as possible.

The fish passes that the Environment Agency have built on weirs such as Howsham and Kirkham are good examples, as are catch-and-release schemes to help young eels on the last bit of their journey.

In recent years hundreds of thousands of glass eels have been netted in the Severn estuary, where they are still relatively common, and transferred to the River Aire in West Yorkshire, Potteric Carr near Doncaster and our own River Derwent.

Also, in 2014 the East Yorkshire Rivers Trust successfully lobbied to have the Derwent tidal barrage open eight hours each day.

This campaign had mainly salmon and sea trout migration in mind, but it suits those baby eels just fine as well and hopefully the next few years will see a recovery of their numbers on a par with their bigger cousins.