Juvenile fish survey 2009: summary

Posted: Friday 2 October, 2009 @ 14:30:45

Between July and September, electro-fishing surveys were carried out on the following river systems: Kanaird (Langwell area), Ullapool, Broom, Little Gruinard (around Fionn Loch), Gruinard (Gleann na Muice), Allt Beith, Tournaig, Sguod, Ewe (Kernsary, Loch Maree burns, Kinlochewe, Coulin areas), Ling, Croe, Glenmore, Glenbeag, Arnisdale and Barrisdale.

 

Most sites were surveyed using the SFCC ‘semi-quantitative’ protocol, where stream sections were fished in a standard way over a timed period, and all fish caught measured and counted. This provides Catch per Unit Effort (CPUE) data, expressed in numbers of fish caught per minute, and provides a good indication of the relative and absolute abundance of different year-classes of salmon and trout at respective sites.

 

CPUE for salmon fry (young of the year) and parr were high in core sites in all systems, though juvenile salmon were not present at all sites. In the north, only salmon parr were found in the upper Kanaird above the Langwell falls. In the Rhidorroch River (Ullapool) salmon fry and parr were found at all sites to the top of the accessible area, at relatively high CPUE. In the River Broom, sites were led by Ross Gardiner of Marine Scotland (who has been carrying out an e-fishing survey of 4 sites in the river most years since 1990); densities were higher this year than last year.

 

Salmon fry and parr were present at all sites in the Abhainn Gleann na Muice (Gruinard catchment) at higher CPUE than in previous years. Around the Fionn Loch (Little Gruinard system) salmon fry and parr were recorded at all sites; but also the first minnow (at mouth of Beannach system) and a charr fry (same site). The little Allt Beith is of interest as a fish pass was installed by Scottish Water several years ago into the Loch Bad a’ Luachraich (’Goose Loch’) so we checked out the spawning burn at the head of the loch for the first time; no juvenile salmon were found. Big salmon parr but no fry were found above the old fish pass below the loch: no evidence of spawning above the old fish pass in 2008. Salmon fry and parr were found throughout the accessible area at Tournaig; salmon fry were found at highest CPUE by an enhanced spawning habitat area in the Sguod system.

 

In accessible parts of the Ewe system, at Kernsary salmon fry and parr CPUE were high, in the Tollie burn (where stocked) parr were present at high CPUE. Around Loch Maree, CPUE of juvenile trout was high in burns; salmon fry were found at highest site in Docherty burn and at moderate CPUE in the Kinlochewe River (rapid growth downstream of village!). In the A’ Ghairbhie below Cromasaig, sal fry were found at high CPUE suggesting adequate spawning habitat in mainstem (therefore less concern about water abstraction from the the Allt a ’Chuirn). Higher upstream in the A’ Ghairbhe, sal fry and parr were recorded at high CPUE in core areas below the Cruive Pool and in rivers above Loch Coulin.

 

In the south of the area, juvenile salmon were found at moderate or high CPUE throughout accessible parts of the Ling and Croe,  and for the first time in headwater areas above falls in the Glenbeag rivers. Salmon parr were found for the first time in the upper Glenmore river above the Bealachasan falls. Only parr were found in the Barrisdale River, we visited stocked areas in the Arnisdale where salmon parr were present. 

 

Survey data will be worked up into a series of reports for river managers during the autumn and winter. Please contact the WRFT biologist for further details. 

 

Many thanks to David Mullaney, Roger McLachlan, Garry Bulmer, Colin Macdonald for  assisting this year and to Ewen Scobie, Alan McGillivray, Alan Cameron, Mark Williams and family, Ewen Ballantyne, Jamie Kuggleman, Alex Day, the SNH Beinne Eighe NNR French student volunteers, Tournaig Estate and other estates for their help and support.