Study
Project update June 2007
The Lough Derg Native Fish Biodiversity Project is now is now into its second year and it is timely that we should have a newsletter just to give people an update on the developments so far. Its been quite exciting really and we’ve come along way from our humble beginnings! Just to recap, the Lough Derg Native Fish Biodiversity Project (Lough Derg NFB Project) was set up to answer a number of questions concerning the native fish community using the most up-to-date and sophisticated scientific techniques. Such question include; Are there different types of trout in Lough Derg and if so how unique are they? Are the different types recognized by anglers in Lough Derg really different? If they are really different, what does it mean? Are they unique?Do these different types of trout have different feeding ecologies? i.e., do they depend on different aquatic animals to survive? Are Gillaroo trout still present in Lough Derg? Do Croneen trout use Lough Derg as a feeding ground? Do trout in Lough Derg compete with other fish species, in particular non-native ones such as roach, bream and rudd? If so are the trout under threat?
And what about that rare fish known as the pollan or “freshwater herring” which only occurs in 5 loughs in the entire globe (see below for more info.) Where do Lough the Derg Pollan spawn? Are zebra mussel, a non-native new arrival to the lough, a threat to pollan eggs in the spawning beds? Do non-native fish species such as roach, bream and rudd compete with pollan?
Sample collection
2006 saw the beginning of the sample collection with anglers enthusiastically taking part in the scientific exercise. Three workshops on sample collection were held for the anglers in Killaloe. Over 100 trout samples have been examined from the lake and another 30 Croneen from the Camcor River near Birr, Co. Offaly, are currently being processed.
2007
The Lough Derg Angling Association which represents eleven angling clubs who fish the lough are currently collecting trout samples for both genetic analysis and stable isotope analysis (i.e., foodweb analysis). The fish are also being photographed according to a specified protocol so any visual differences can be identified. The samples are collected together, dried and labeled in the Shannon Regional Fisheries Board laboratory prior to shipping to scientific experts in Northern Ireland (team leader Dr. Paulo Prodohl, Queens University) for genetic analysis and Canada (team leader Professor Mike Power, University of Waterloo) for stable isotope analysis. In 2006 regrettably not all samples had matching photographs, genetic and frozen tissue (for stable isotope analysis) though and sample collection has continued into 2007 so we can improve on the overall quality of samples. Sampling by the use of gillnets has continued in a selective sampling programme to target coarse fish species within the lough.
The Lough Derg Sub-aqua Club also joined up to give a hand and collected 25 sediment samples from around the lough to see if we could find where the pollan were spawning. No success yet but the sub-aqua team will continue their efforts into the winter 2007. Currently they are collecting zebra mussel samples and invertebrates samples to complete the stable isotope sampling. The identification of the pollan spawning ground is essential for the sustainable management of navigation and flood water management on Lough Derg.
How many spots on a Lough Derg trout
Anglers are well aware that trout have spots. Nothing new there, but trout in the same lake can also have different numbers of spots from each other. The big question is, does this mean anything or is it just part of natural variation you would expect in a lake? A recent international study on rainbow trout showed that the spotting pattern is genetically fixed, and so it is therefore likely that the same applies for the Lough Derg trout. So with the assistance of three transition students from Villiers school in Limerick, we counted the spots on trout taken in Lough Derg and Croneen caught in the Little Brosna and the Camcor Rivers and we got the following; the average number of spots for Derg trout were 208 against 136 spots for the Croneen. The difference is even more dramatic when we compare maximum numbers of spots per fish, with a massive 399 for Derg fish compared to only 231 for the Croneen. We are not sure what this means yet but indications are that there really are different breeds or types of trout within the lough.
Funding
The project partners have managed to secure welcome and necessary funding for the project. Tipperary Leader are funding elements of the trout and pollan programme and the Heritage Council are funding part of the pollan sampling (e.g., substrate mapping) not covered. We have recently supported Queens University bid for funding for an EPA Biodiversity PH-studentship to examine in more detail the genetics of the trout in the catchment as well as the juvenile fish.
The pollan are not only special; they are a different species Goddamnit!
The recent report by Paulo Prodohls team in Queens University makes for stunning reading. Dr. Catherine Bradley who carried out the genetic study, including on Lough Derg samples found that the pollan are unique to Ireland having split from the mother population of whitefishes known as Coregonus autumnalis some 165,000 years ago. That’s long before the end of the last Ice Age. The pollan should now be formally recognised as Coregonus pollan. And the Lough Derg pollan are genetically different from pollan in the other three Irish lakes studied.
Pollan - Local Area Species Biodiversity Action Plan
A species action plan has been developed by the Shannon Regional Fisheries Board for the Clare Biodiversity Forum concerning pollan in Lough Derg. This details where work is urgently needed to protect this unique fish and we hope to launch this in August 2007. So keep a look out for details…………………..
Media coverage of the project
Print articles have appeared in the Limerick Post, Nenagh Guardian, the Tipperary Star and the Irish Examiner. Radio interviews have been conducted on RTE radio 1 and Tipp FM.
If you have any information on Pollan, or other rare species (we are also collecting specimens on lamprey which are sometimes found attached to fish caught by anglers) or would like some information we would love to hear from you.
You can also get more information on rare Irish fishes including pollan at the Irish Char Conservation Group website www.charr.org or write to The Secretary, ICCG, 11 Poddle Green, Kimmage, Dublin 12.
Supported by the Shannon Regional Fisheries Board, Lough Derg Angling Association, Lough DergSub-aqua Club, Irish Char Conservation Group, Lough Derg Science Group, University of Waterloo Canada, Queens University Ulster, Clare Biodiversity Forum, Tipperary Leader, Heritage Council.
The Lough Derg Native Fish Biodiversity Study is ongoing with the first batch of samples sent to Canada and Belfast for analysis. The samples consist of representative samples of perch, pike, roach, bream, eels and trout. When results are available it is intended to hold a seminar in Killaloe in the autumn of 2007 to deliver the preliminary findings. A random aging of an 8lb brown trout by Dr Fran Igoe, Shannon Regional Fisheries Board showed that it lives for 2 years in a river before migrating to the lake and becoming cannible. It was found to be 8 years old. Dr Igoe will demonstrate the methology in aging scales to anglers in September. The Lough Derg Native Fish Biodiversity Study members wish to acknowledge the assistance of Tipperary Leader in supporting this research project. Without their support it would not have been possible to engage the services of the Universities in Canada and Belfast.
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