news/editorial

5 February 2017 News/Editorial

You can tell nothing much from the 2 days of reasonable fishing conditions last week, except that there are some springers about, and more kelts than last year.

We should not expect too much of February, the average Tweed rod catch in recent decades being remarkably consistent at or around 250 salmon for the month.

But if there is any consensus emerging about what is going on with our fish after the last 3 years, it is that the pendulum has shifted in favour of (multi sea winter) salmon, rather than grilse. It is something to do with North Atlantic sea temperatures and the AMO (the Atlantic Multi-Decadal Oscillation).

The comparatively simple hypothesis is this; the warmer the North Atlantic, the more plentiful will be the food for salmon close to home, ergo smolts and post-smolts do not have to travel far from their native UK rivers for lunch, they grow and mature quickly, and come back after one year (to spawn) as grilse.

In a cooling North Atlantic, the opposite is true. Our smolts/post-smolts not only find much less food close to home, but they have to travel 1000s of miles further. They grow slower, do not mature quick enough to return after one year as grilse, and when they are ready to come home, the travel time and distance is very much more. In short, they will (mainly) come back after 2 years as (bigger than grilse) salmon.

If you asked 100 people what is happening to North Atlantic sea temperatures, all 100 would say they are getting warmer, so indoctrinated are we by reducing Arctic sea ice and ever warmer world temperatures.

They would be wrong.

For 17 years from 1990 to 2007, the AMO saw the North Atlantic becoming ever warmer, when, quite suddenly post 2007, it started cooling, and really quite sharply. It is now, in 2016/17, very roughly the same temperature as in the 1980s. The prediction, from learned scientists and meteorologists, is that it could go on getting cooler for decades (hence the “multi” in the acronym AMO) to come.

So if we are to get many more salmon than grilse, what none of this tells us is when these salmon will come back. Will they come in the spring, as in the period 1920-1966, in the autumn, as in the 1970s and 1980s, or, now that we have little netting, in the summer?

Dr Ronald Campbell provides evidence from the past that the change from grilse domination to salmon domination takes longer than the other way round…….which could account for the last 3 poor years here on the Tweed ie we have lost our grilse, but not yet developed a full blown salmon run.

All of which is quite exciting.

Will they start coming back in greater numbers in February and March, as they did between 1920 and 1966?

Probably not, or at least there is no sign of it so far.

But, after recent surprises to established norms, it could happen.

I, for one, will be watching catch numbers, over the next few days and weeks, here on the Tweed, on the Dee and on the Tay with added interest.

Something is going on…….. we just do not yet know precisely what it is.