Inland Fisheries Ireland, with the assistance of the Office of Public Works, population geneticists from University College Dublin and Irelands trout anglers have commenced a study of the genetic makeup of trout stocks in Ireland’s larger riverine catchments. The first two catchments to be examined were the Suir and Boyne in 2011 and the results are now available.

Scientists refer to this type of study as a “micro-satellite DNA analysis”. In layman’s terms this means that a chemical analysis of scale samples from the fish can reveal their genetic makeup – a similar process to that used by police forces worldwide to identify criminals.

In the case of the Suir and the Boyne, trout stock samples of young fish from all of the major tributary sub catchments were examined genetically. The analysis showed that, in genetic terms, the young trout from these different rivers were discrete –i.e. in the case of the Suir young fish from the Drish were genetically different to those in the Anner, or the Tar, or any other tributary; and in the case of the Boyne young fish from the Stonyford were genetically different to those in the Skane, the Knightsbrook, or any other tributary.

The next stage in the process was to examine samples of adult fish from the main stems of these river and to relate these back to the tributary “genetic types”. At this point IFI sought the assistance of angling clubs.  Anglers were requested to take a few scales from any fish they caught, place them in an envelope and record the date of capture, capture location and the  length of the fish on the individual envelope. Many of the fish scaled were returned alive by the anglers once these details were collected. The enthusiasm of the anglers was key to the success of this project.

Find out more here