Historic catch records show that there have been significant changes in the numbers, run timings and sizes of Tweed Salmon over the last 200 years or so and that these changes are largely due to sea surface temperatures.
In this review paper, the Tweed Foundation's Dr Ronald Campbell discusses the catch trends in Tweed Salmon and what they could mean for the future. The review paper can viewed using the link below and the full paper can be issued on request.