Everyone who fishes the Tweed is incredibly concerned about the great change that appears to be taking place in the catches. Autumn grilse have declined while Summer fish (mainly Salmon) have increased in number and this can now be illustrated by the graph below. This shows that in 2016, catches made before the 1st of September outnumbered those made afterwards for the first time since the 1970s.
Catch figures for the Tweed as whole do not go back much before 1950, but those for some individual beats do. The example below is from a Middle Tweed beat, showing its catches before and after the 1st September from 1887 to 2016.
On this graph, three transitions between earlier and later running fish predominating in the annual catches can be seen: the present day one (later to earlier), the one in the early 1970s (earlier to later) and a more drawn out one around in the early 1920s (later to earlier).
The present change is not just happening on the Tweed. The Environment Agency has just published a graph showing that in 2015 anglers in England and Wales caught more salmon than grilse for the first time in their records and that grilse numbers have declined rapidly in recent years. This graph can be found as Fig 18 on page 41 of “The Current State of Salmon Stocks”, Appendix 2 to “Managing Fisheries in England and on the Border Esk” which is available as a downloadable pdf here.
There are also other graphs of interest in this publication: Fig 7, page 12, shows how the size of grilse on the R. Tamar in Devon has declined from an average of around 6lbs in 2003-04 to around 4lbs today. Fig 8, page 13 shows how the return date of grilse to the R. Tamar has changed: around 2004-05 only 10% of grilse had returned by the first of August, but in 2016 over 60% did.
These trends towards smaller and earlier running grilse are also seen on the Tweed, showing how widespread these changes are. Netting data from the Tweed can also show similar changes going back in to the 18th century
You can learn more on these long-term changes in a Tweed Foundation YouTube video, which explains what our Salmon may now be experiencing throughout the UK.