As can be seen from this chart, when numbers caught in the second half of the season started to increase in the late 1940’s (black line), average size (white columns) began to decline slowly (solid blue arrow). The late 1950’s / early 1960’s was the time when the Tweed, in common with other rivers, swung away from the Spring run being dominant back to the Autumn becoming the major run, the actual change-over being in 1968 (red line) when more than 50% of the annual catch was caught after the 1^st of July for the first time since 1922 (red line), which marks the previous, opposite, changeover, from Autumn to Spring dominance. This coincidence in timing suggests that there might be some link between the two trends, more Autumn fish meaning more smaller fish (Grilse). In fact, over the period before 1922, as numbers of Autumn fish declined, there was an increase in their average size (dotted blue arrow) , which does support the idea of a link between numbers  and age composition of Autumn catches and average size. During the Spring Salmon dominated phase, it was Autumn Grilse that were at low levels rather than Autumn Salmon, giving a higher average size for Autumn fish overall. As the Spring Salmon phase ended, Grilse numbers increased again, lowering the average Autumn fish size.