Tagged Grayling No. 249 (tagged at Birkenside on the Leader on 16th December 2006) was recaptured there on 27th January 2009.
At four and three years between tagging and recaptures, both these fish show that the tags are holding on well and that fish can survive long after tagging.
A tagged Grayling in the river
Although the Grayling of the Tweed are an alien species introduced in the 1850’s, samples were contributed to a UK wide genetics survey organised by the Grayling Research Trust (GRT) to see if their origin could be traced and whether there were any signs of genetically distinctive populations beginning to form in different parts of the Tweed.
The results suggest that the Grayling introduced to the Tweed, Clyde and Earn originated from the Derbyshire Derwent system, while those introduced to the Annan originated from the Severn-Wye system. It was also found that while genetic variation was low within the different populations sampled from the same rivers, between these populations genetic variability was high. Low within-population and high between-population genetic variation might be explained by the formation of local breeding groups, with little tendency of individuals to move among groups, at least for breeding purposes. This finding is of great interest since it mirrors the pattern we have been finding from tagging, which is that very few Grayling ever move from the site at which they were first tagged. Any sort of long range movement, like that made by Tag No. 407 is very exceptional.
These genetic results confirm the management lesson learned from the tagging results: that good catches of Grayling do not necessarily mean large numbers of fish since recapture rates are high, and that local populations could easily be over-exploited since there is little movement between them.
Grayling tagging comprises one element of the Tweed Trout & Grayling Initiative, a programme of work which has been ongoing since early 2005. Further details about all the areas of study within the TTGI can be found at its dedicated website from this link: TTGI
The Initiative is always looking for more volunteers to get involved. If you would like further information, or to offer help with some of the practical studies which the Initiative is undertaking, contact Kenny Galt (Trout & Grayling Biologist) on 01896 848271.