Why flow rates have killed River Thames salmon

I do love a coincidence! I was about to tell you about historic Thames flow rates, and the decline thereof, thanks to a 1975 Angling magazine loaned to me by a lovely man called Eric Pace, who used to fish for turbot.

He has an article in the edition he lent me, bemoaning the fact that numbers of turbot in the West Country are in decline. That decline proved terminal, a bit like the Thames salmon experiment and therein lies the coincidence.

In the magazine there’s a remarkable segment where Dave Steuart, a genuine angling legend who ran a tackle shop close to the tidal Thames, asks searching questions via an open letter to Peter Black JP, head of Thames Water.

Replies were printed and the questions are relevant still but that isn’t my thrust here. Information comes from the statistics on river flow rates for the Thames.

In 1975 the flow over Teddington Weir, the tidal limit on the River Thames, was 1,300 million gallons per day (mgpd) on average. In 1973 – a drought year (and 1976 and 77 were to come) this was as low as 450mgpd. In 1975 the statutory minimum flow over Teddington Weir was 170mgpd. Obviously this low figure must have been unusual for the average to be as high.

In 2006 the flow over the weir only reached 170mgpd on 15 days and on some days it was zero – unless one takes into account the ‘salmon pass’ built to enable the silver tourists to make their way upstream to spawn. Sadly – or stupidly and wastefully - by the time the passes were finished, abstraction from the Thames and its tributary the Kennet, was so bad none of the pea gravel which salmon need to cut their spawning redds was exposed. This is due to silt build up due to lack of flow (abstraction, and silt incursion from the Kennet and Avon canal, which another band of geniuses decided to open up at that time).

The lack of freshwater flow on the tidal river would mean any salmon, except at times of flood, would be trapped there swimming back and forwards with the tide.

I used to see salmon in the Thames in the 1980s, several on some days. There were one or two anglers fishing for them in the weirs at Sunbury and Molesey – and they’d catch a couple each year. I’ve not seen one for more than 20 years and haven’t heard of one in almost as long.

Thanks, EA, for wasting all our money for all that time.