Preliminary Observations in Relation to an Adult Fish Stock Survey of L. Corrib completed in February/March, 2012
An adult fish stock survey of Lough Corrib was carried out by Inland Fisheries Ireland over the period February 27th to March 15th. This is the second such survey on the Lough, the only other complete survey having been carried out previously in 1996. The primary objective of the exercise was to update IFI’s knowledge in relation to the status of fish stocks in this water in the knowledge that there have been a number of major ecological changes in this water since the previous survey was undertaken in 1996 – Roach have now had a thirty year period to integrate with other stocks in the lake, a population of Zebra Mussels has become established in this water since the early 2000’s and, more recently, a South African aquatic plant (Lagarosiphon major) has been growing vigorously in parts of the lake. A management programme is in place to control the latter species.
The results of 1996 survey suggested that Arctic Char, a native fish species in L. Corrib, appeared to have become extinct in the 1990’s. It was hoped that the recent survey (2012) would update the status of this fish species.
In 2007 and 2008 a micro-‐satellite DNA study of the trout stocks were carried out in the Corrib Catchment. This allowed IFI to genetically identify the individual stocks from the major stream catchments and, subsequently, to determine the contribution of each of these to the mixed adult stock in the lake. The present survey provides the opportunity to repeat this exercise at reasonable cost because the original genetic patterns for each tributary sub catchment will still be valid and therefore only the adult sample from the lake needs to be examined genetically. This exercise will answer two questions;
a) Has the contribution of trout from individual sub catchments to the adult stock in the lake changed since 2008?
b) The fact that a GPS reading is available for every trout captured in the 2012 survey means that, for the first time, the distribution of fish from the individual tributaries throughout the lake itself can be determined.
The reader should note that comment on the status of stocks in this document is provisional. Detailed analysis of the data is required before more definitive comment can be provided.
Eel Monitoring Programme: 2009 - 2011
In response to advice from the International Council for the Exploration of the Sea (ICES) that the European eel (Anguilla anguilla L.) is endangered and that the fishery is unsustainable the EC regulation establishing measures for the recovery of the European eel (Council Regulation 11000/2007) was created. This regulation for the recovery of the eel stock required Ireland to establish an eel management plan to reduce eel mortality and ensure an increase in the number of silver eel escaping Ireland to spawn. Ireland’s management plan involved closure of the fishery, mitigation of hydropower, ensuring upstream eel migration at barriers and improvement in water quality. In June 2009 the EU accepted our national plan as an adequate address to the issues raised in the regulation. Under the regulation each member state must report to the commission initially every 3 years until 2018 and subsequently every 6 years. The next review is due in June 2012.