The electro-fishing effort in 2008 centres on the Leader and Whiteadder systems covering all major/significant trout spawning burns. Whilst the Whiteadder system will be sampled in late August, sampling has already begun on the Leader system. Shown below are two electro-fishing sites on a Leader Water trout spawning burn.
Photo A Deep water sampling site Photo B Shallow water sampling site
The results from this burn were of great interest as there is a weir towards the bottom of the burn, the influence of which on the trout population was unknown. The first site (Photo A) is a “deep” water (relative to the burn sampled) sampling site designed to sample trout parr (one year old and older juvenile trout) and the second site (Photo B) is a “shallow” water sampling site designed to sample trout fry (0 year old or young-of-the-year).
Whilst the trout sample from the deep site, shown below, would at first seem encouraging, larger fish like these are uncommon in a burn of this size and takeable sized trout (the biggest trout in the bucket is takeable) are very rare.
Sample of fish from deep water site recovering after being fished out of the site
for monitoring purposes, and before being returned to the water
Normally trout reaching this size would have migrated out of this burn to find deeper water and greater food supplies (in the process of doing this trout “stock” the areas fished by anglers). This suggests that the obstacle further down the burn was, at least to some extent, “isolating” the trout population and restricting migration in and out . (In an isolated population adults must remain in the isolated section or there will be no fish to spawn and produce juveniles in the future.) To further back up this conclusion, no fry were found in the shallow site indicating that no adults had spawned in or near this part of the burn suggesting that the obstacle was un-passable or very restrictive during the dry autumn last year when trout would have tried to ascend their spawning burns to reproduce. The results of the survey therefore indicate that this trout spawning burn is not fulfilling its potential in helping to stock the area where anglers fish due to the obstacle.
As you would expect the next step for the TTGI is to ease trout passage over the obstacle!
Further information about the Tweed Trout & Grayling Initiative can be found by clicking here.