Fish catches are the best historical information that we have and the analysis of historic and recent catch data allows us to identify the natural, long term changes in the Tweed’s fish populations. When appraising fish stocks it is always important to take the long view, and the historic catch data collected from the Tweed shows some very long-term trends for both Salmon and Sea Trout.
Historic catch records show how the sizes and run-timings of the fish have varied greatly over the years and give the context for assessing the present day situation. Establishing long-term trends shows if there are large-scale changes that cannot be countered, though could be managed, while variations outside known parameters from the past could be a warning sign of problems in the current day.
Studying the Tweed’s historical records has provided us with a great deal of insight and has increased our knowledge of variation in the Tweed’s fish stocks. Some of the more significant findings include:
A summary paper looking at the catch trends in Tweed Salmon by Dr Ronald Campbell can be viewed here.
This presentation by The Tweed Foundation's Dr Ronald Campbell describes the biology behind recent changes in Tweed Atlantic Salmon.