GFT creates a Galloway Rivers Standard for Timed Electrofishing
17th Feb 2020 by Rowan McCleary
A review of recent timed electrofishing data on the Luce and Urr in relation to a Galloway Rivers Standard
Over the winter and with the guidance of Brian Shaw at the Spey, GFT have compiled a set of standards to help categorise our Luce and Urr timed electrofishing data (please see our website Projects page).
From the colour-coded data tables, it can be seen that within the Luce, salmon fry have been absent above Lagafater Dam since 2017. Sites LT1, LT2 and LT3 where salmon have been absent in recent years are positioned within the very upper reaches of the main river. Other notable variation in annual data can be seen during 2018 when despite a very dry and hot spring/ early summer, results gathered were some of the highest abundance of salmon fry found during the timed survey period, particularly within the lower reaches of the main river. 2019 drop in densities of fry could be contributed to an increase in predation pressures since surveys were undertaken over six weeks later than normal (because of high river levels preventing safe access to the river and successful capture of fish). However, during 2019, the numbers of parr were among the best recorded across the last four years of data collected by this method.
With regards to Urr data; fry were in high abundance during 2018 but mostly found in moderate numbers in 2019. This may be a consequence of undertaking surveys over six weeks later than normal. With regards to parr findings; although parr are not specifically targeted for in these surveys and they often evade capture in higher flows and under low conductivity conditions (mostly within the upper reaches of the catchment); in general, they have been found in low to moderate density. This is not a good reflection on true numbers since the survey area often targets shallower and sometimes marginal areas of flow where fry are found, as opposed to deeper faster, mid-channel reaches where parr reside. Within the sites of Netheryett and downstream of Old Bridge of Urr, there is simply very little larger-sized substrates present that would encourage parr to inhabit.
GFT are confident they have managed to compile a Galloway timed electrofishing standard that relates consistently with their findings on the Luce and Urr to date. Ideally, the standard will incorporate at least five years of data and with future timed electrofishing efforts added, GFT will make necessary adjustments to the standard.