PROTECTING & IMPROVING THE TAY SYSTEM
RIVER TUMMEL SMOLT TAGGING PROJECT
In this major project which commenced in the spring of 2016, salmon smolts are caught in two “rotary screw traps”, one in the River Garry and the other in the Errochty Water just upstream of where these two rivers meet at Struan. Smolts caught are tagged with “PIT” tags inserted into the body cavity and then released to continue their journey out to sea. On their return as adult salmon, surviving tagged fish are detected by an automated PIT tag detector within the fish pass at Pitlochry Dam. The objectives of the project are as follows:
1- Setting-up an “index” river of marine survival of salmon:
From a given number of tagged smolts released, the number of adults subsequently detected at Pitlochry Dam will provide an annual index of survival from smolting to adult return.
2- A means of calculating smolt production from subcatchments
Trapping will also be used to estimate the total number of smolts migrating from upstream of a trapping sites by mark-recapture. In conjunction with (1), it should be possible to determine at index sites the extent to which changes in adult salmon numbers are caused by changes in smolt production or marine survival. Specifically with regards to the Garry, this will help in the monitoring of the restoration of the upper Garry salmon population and assessing the value the rewatering of this river has had.
3- A means of establishing any losses of smolts within the Tummel system
In years when enough smolts to satisfy experimental criteria are caught, it may also be possible to assess any losses of smolts, both in travelling through the lower Garry/Loch Faskally and passing through the turbines at Pitlochry Dam. As well as releasing smolts at the tagging site, this entails transporting and releasing some smolts just above Pitlochry Dam and some just below the Dam. Should enough smolts be present, the project could, in time, be extended to establish survival rates of smolts passing through dams in the upper Tummel system, e.g. Clunie Dam or even Gaur Dam.
4- Results so far
A summary of the results of this project to 2018 can be found here.
This is a joint project between Marine Scotland Science (MSS), Tay District Salmon Fisheries Board (TDSFB), Tay Rivers Trust (TRT) and SSE.