news/editorial

30 July 2017 News/Editorial

Bear with me on this.

What is 3,000 km multiplied by an average of say 10 metres? That’s 30,000,000 (yes 30 million) sq metres?

Then what is 30,000,000 multiplied by 185 divided by 100? It’s 55,500,000 or 55.5 million.

I’m talking salmon fry, the result of Tweed’s last autumn/winter’s spawning.

Now watch the Tweed Foundation’s recent video

http://www.rivertweed.org.uk/news/?p=5957

The Tweed’s 2017 electrofishing programme is in progress and the reference above takes you to their interim report from 4 electrofishing sites. Each one shows a significant improvement on the same sites in 2016 (bad because of the 2015/16 winter floods) for juvenile salmon (fry) numbers, with 185 salmon fry per 100 square metres being the average of the 4 sites.

The accessible area for Tweed salmon spawning is somewhere around 3,000 km, and let us assume that the average width of those 3,000km is 10 metres (more in all main stems, less in the spawning tributaries), giving a Tweed salmon spawning area of 30 million sq metres.

So if Tweed produces on average 185 salmon fry per 100 sq metres, and we have 30 million available sq metres, it can produce, based on actual averages achieved in 4 sites, 55.5 million fry.

They do it themselves, it costs nothing.

Of course, up to 95% of these fry die (the “losers” as Dr Campbell calls them), because the riverine food supply and available space simply cannot support that many, leaving 2.775 million to go down the river, a year or two later, as smolts.

Of these smolts, only 5% survive their sea journey (used to be 30% in the 1960s) to come back as adult salmon, leaving the ultimate “winners”, those we anglers fish for, at just 138,750.

A lot, but maybe only just enough for a successful rod fishery on a river as big as the Tweed, when we know that anglers only catch less than 40% of springers and less than 10% of autumn/summer fish. If you press them, our scientists will confess that in 2010, when we caught over 23,000 salmon here, the adult salmon population may well have exceeded 250,000.

All of this is theoretical, of course, and the possible variations in the maths and consequent numbers are endless.

But what we know for sure, and what those who would have a hatchery must begin to understand, is that putting more juveniles into the river (and “unfit” juveniles at that, because they would have been reared in artificial conditions), at vast cost, will achieve precisely nothing when the salmon themselves produce so many millions.

Look at the video again…... and those wriggling masses of little fish. Even better, sign up to go along on an electrofishing trip and see for yourself. You would be most welcome and the Foundation gives a “Contact us“ link in the wording accompanying the video.

Those millions of wild little fish, and the adult wild salmon which produce them, are the future.

Spending £millions on a hatchery is not.

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Is anyone seeing any numbers of salmon anywhere? I walk by the river every day and hardly ever see a splash.

By the end of July there should be an accumulation building somewhere, but there isn’t.

We have had our best July ever here, but nobody ever sees one, or at least rarely. It is as if some fish arrive, you catch a few without seeing any, and then they are gone…….but where to?

Let us suppose the rod catch so far is somewhere around 2,000 to 2,500 salmon, that should in turn mean around 6,000/7,000 salmon in the system.

But where are they?

Lurking, or even skulking, and uncatchable, in a series of deep holes between Tillmouth/Tweedmill and Boleside?

It must be so.

More importantly, if all we have in the river is 6,000/7000 salmon, and so far barely a grilse in sight as we go into August, when are the numbers of salmon or grilse going to appear?

Pre 2014, I would have said they would come as usual from August onwards.

Now I am not so sure. Logic and optimism tell me…. they must be still to come.

But are they?

We will find out soon enough.