It seems that freezing temperatures mean more salmon on all major Scottish beats

In recent years, the first day of the salmon fishing season on the River Tay has tended to bring as many bad news stories to the surface as fish. However, today, when the pipes and drums lead the anglers to the banks of the river at Dunkeld for the first cast of 2011, the tune might just be a bit jauntier than usual.

For 2010 was a good one and autumn, in particular, a bumper time for landing salmon. Interestingly, if you chase the king of fish, probably the best thing to do is to pray for snow, for scientists believe one of the reasons for last year's successes was the bitterest winter in Britain for 31 years.

Jackknifed lorries, school closures and burst pipes might not have been everyone's cup of tea. For the scaly kind, however, the weather was lovely.

Scientists believe Atlantic salmon or salmo salar have been returning to our rivers in lower numbers and in poorer shape in recent years because something has been changing out at sea - and not for the better.

Because salmon generate millions of pounds for economies, cross-country scientific collaborations like SALSEA, put in place by the International Atlantic Salmon Research Board, have been ploughing resources into finding causes for the change.

One of the most quoted, and probable, theories is that rising sea temperatures, caused by global warming, have led to the plankton eaten by salmon moving further north to cooler water. This is believed to cause the salmon to prolong their already improbable journeys to reach food. As a result, more are suffering, risks are higher and some believe the fish are not genetically programmed to tap these more northerly feeding grounds.

"The general decline of recent times coincided with milder winters and this has affected other fish as well," says Dr David Summers, director of the Tay Salmon Fisheries Board.

"The last two winters have been different and much more severe. Some beats in 2010 on the lower half of the Tay did their best for a number of years and this was borne out by other rivers, too, like the Tweed. What it points to is better conditions at sea," he says.

Of the 16 lower Tay beats in 2010, almost all reported catches significantly higher than in 2009. Almondbank, near Scone Palace, had increased from 322 fish in 2009 to more than 700, while at Cargill, three miles north of Stanley, 419 fish were landed compared to 245 the year before. This was up almost 80 fish on the five-year average.

It was here, at Cargill, that the biggest salmon of the year was hooked. The 34lb hen fish - the biggest taken from the Tay in five years - was caught, then returned, on the very last day by Alistair Sheach.

"At Cargill, we were probably in line with everyone else; up on the five year average and a fantastic summer and autumn after a poor spring," comments David Godfrey, chairman of the Tay Ghillies Association.

"The harder winter has got to have helped. There is a direct link to sea temperatures and the cold winter probably helped to keep the salmon's food source in the right place, which meant the salmon came back earlier than in recent years, and fatter.

He adds: "I think there has been a bit of a downward spiral on the Tay but I believe we are on the way back again."

Despite this return of confidence, the controversial 100 per cent catch-and-release policy, introduced last year, will not be lifted this season. All salmon caught until June will have to be returned.

Still, if winter continues to freeze everyone to a halt, at least it may save some ghillies from going part-time and fishermen might fork out the cash again to fish one of the most famous salmon rivers in the world. That, surely, can only be a good thing.

For more information, www.tdsfb.org

• This article was first published in The Scotsman on January 15, 2011