NATURE Ranching Salmon of Knowledge

Mayo rears true salmon of knowledge


Marine Life
John Paul Tiernan

The first salmon of the 2010 season was caught on the River Moy on the last weekend in February. In the Delphi valley in the other corner of the county, the first was caught the day before. Almost 30 per cent of Ireland’s total salmon catch is taken in the Mayo/west Sligo region. Aptly enough, the region generates most of the quality, up-to-date knowledge on salmon, not just for Ireland, but for the entire North Atlantic.
Midway between the Moy and Delphi Fisheries, the Burrishoole Fishery at Lough Furnace outside Newport has been quietly establishing itself as an internationally recognised salmon-research centre since the 1950s, and one of the world’s longest-running salmon-trapping facilities. The scale of research it has undertaken since opening is impressive, encompassing salmon genetics, stock enhancement with salmonoids and climate-change studies.
One of the activities that Burrishoole pioneered is a most terrestrial-sounding pursuit; salmon ranching. Ranching is the rearing of smolts (salmon ready for salt water), which are derived from grilse (salmon which return after one year at sea). A fish farm must provide all the food necessary in a fish’s life cycle. Ranching, however, means the fish live where and how nature intended once released.
Because it protects the juvenile salmon until the smolt stage, ranching produces much more fish than the river otherwise would. When the mature fish return to the river of spawning, as many as possible are caught and the eggs and milt (male gamete) harvested to spawn the next generation in the ranch’s line. Experiments on the Delphi Fishery have shown good returns, matching or outdoing the native stock’s returns from the Atlantic.
Micro-tagging and tag retrieval initiatives directed by the Marine Institute mean that Burrishoole does not just have a healthy stock, they have a useful informative ‘herd’ of ranched fish.
Data from the fish are used by the International Council for the Exploration of the Seas to determine the state of Irish stocks, and according to the Irish Marine Institute, the Burishoole fishery system is one of the key index systems for salmon in the North Atlantic. This and other recent research utilising Burishoole salmon as indicators of global climate change means Mayo’s salmon are not doing a bad job in living up to their Salmon of Knowledge legend.

John Paul Teirnan, Louisburgh, runs www.irishmarinelife.com, a website dedicated to the creation of knowledge of our marine ecosystems. He is currently studying for an MSc in Marine Science.