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 a “rotary screw trap” in the lower reaches of the Errochty Water, a tributary of the River Garry. The 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 will be detected by a PIT tag detector to be installed in the fish pass at Pitlochry Dam during the winter of 2015/16.
The objectives of the project is following:
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 site(s) by mark-recapture. In conjunction with (1), it should be possible to determine at an index site (e.g. the Errochty Water) the extent to which changes in adult salmon numbers are caused by changes in smolt production or marine survival.
3- A means of establishing any losses of smolts within the Tummel system.
If enough smolts to satisfy experiemental criteria can be caught, it will 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- A means of establishing the contribution of the restored River Garry
An adaptation of (2) which might take place in future could estimate the number of smolts produced in the upper Garry if and when flow is restored and its contribution to the number of adult salmon passing through Pitlochry Dam.
This is a joint project between Marine Scotland Science (MSS), Tay District Salmon Fisheries Board (TDSFB), Tay Foundation (TF) and SSE. The Errochy Water was chosen initially as the main trapping site because it is seen as a productive tributary with a flow regime particularly amenable to trapping. Other sites may be added in future.