Lough Ree Survey
Inland Fisheries Ireland is currently carrying out a complete fish stock survey on Lough Ree to assess the current status of coarse, pike and game fish populations in the lake. The survey will take place between 24th February and 14th March 2014 and will involve netting of 200 sites throughout Lough Ree. The survey will involve Inland Fisheries Ireland staff from the ShRBD and research staff in Swords and will include a total of five boat crews, two safety crews and processing crews, based around Lough Ree. The time of year of the survey is comparable with netting surveys on other major lakes in Ireland over the last 30 years or so. The type of information gleaned from the survey will include catch per unit effort (CPUE’s) for each fish species, size distributions of fish caught, aging for all species and microsatellite (DNA) analysis (for brown trout). Sampling to assess the distribution of introduced (invasive) species will be carried out, with particular reference to the invasive ‘Asian clam’ Corbicula fluminea. The genetic analysis of the brown trout will contribute the survey work carried out in 2013, with participation from anglers on Lough Ree, Lough Derravaragh, Lough Owel and the River Suck. In 2013 anglers sampled scales from adult trout caught in these areas and submitted these samples to IFI for DNA analysis.
In addition all the major sub-catchments around Lough Ree, River Inny and River Suck were electro-fished in 2013, to help build up a baseline by which adult trout caught in Lough Ree, River Suck or Inny Catchment can be attributed to the rivers in which they were spawned. This is very exciting work and will help build up a picture of what rivers (or parts of river sub-catchments) are contributing to the adult brown trout populations on these major lakes. Similar work on the major western lakes have shown that the native brown trout can undertake extensive feeding and spawning migrations and has also shown (for example the ‘Croneen’ trout of the Camcor/Little Brosna system) that there are genetically distinct populations of trout which undergo large migrations from specific river systems to feed in large lakes like Lough Derg and Lough Ree.
Another aspect of this current netting survey will involve floy tagging of pike. Floy tags will be inserted below the dorsal fin of the pike and each fish will be released. Each tag will have a unique reference number which can easily be identified on later recapture of the pike. Anglers will again be asked to record these tag numbers and potentially the length of fish, particularly during the major pike angling tournaments on Lough Ree in 2014. This will work as a mark-recapture method for estimating pike numbers in the lake. It could potentially provide information on the growth rate of pike also.
The survey crews will be very visible on Lough Ree over the next few weeks and all sets of nets will be marked with distinctive buoys labeled ‘IFI Survey’. Any anglers or other lake users are asked to be vigilant if out and about on the lake over the next few weeks and to avoid snagging in the nets. Inland Fisheries Ireland would like to take this opportunity to thank the relevant angling clubs for their support and contribution to the survey datasets over the last twelve months.
