The Sea lamprey is a primitive eel like fish, which lacks true bones and jaws. They belong to a prehistoric group of fish known as the Agnatha or "jawless fishes". In Pennsylvania, lampreys appeared in the fossil record 280 million years ago. This is even before the dinosaurs were on earth.
Adult sea lampreys are heavily blotched dark green, grey or black on sides and yellowish-white ventrally. Instead of jaws, they have a large sucker for a mouth, and instead of gills they have holes through which they breathe. These fascinating creatures spend the first few years of their lives in burrows in silty areas of rivers filtering organic material. They then metamorphose and migrate to sea and parasitise on fish such as salmon or herring, by sucking onto their host and digesting their juices. This mode of behaviour has given them a bad name. This is probably justified in parts of the US, where they are not a native species, but were introduced by man, such as in the great lakes of Ontario and Superior.
Although the benefit of salmon to lamprey is obvious, a reciprocal benefit has been known to many local Limerick people for generations. Known locally as the "lamper eel", the sea lamprey enter the river to spawn usually about May and dig the same gravels used by salmon to spawn later in the Autumn. Essentially they clean and prepare the beds for use by the salmon. This was recently proven scientifically by Eamon Meskell of the National Parks and Wildlife Service, through his studies of the spawning behaviour of lamprey and salmon in Castleconnell.
The EU has listed lamprey and salmon as species requiring special protection under the Habitats Directive. Ireland is obliged to designate Special Areas of Conservation to protect them. One such area is the Annacotty stretch of the Mulkear River.
The Shannon Regional Fisheries Board together with a number of partners is working towards the conservation of lamprey and salmon on the Mulkear River. This process is known as catchment management.
Over the last few years Dr Fran Igoe of the Shannon Regional Fisheries Board has carried out a study of the adult spawning lamprey by snorkeling below Annacotty weir in association with River Monitoring Technology. He estimates that on one day there were in excess of 420 adults spawning immediately below the weir. He carried out exhaustive surveys upstream of the weir at targeted locations and found little or no sea lamprey, this may show that the weir at Annacotty is preventing lamprey from getting upstream to spawning sites. A subsequent project with the help of the Office of Public Works, National Parks and Wildlife Service and the Shannon Regional Fisheries Board assisted at least 114 lamprey to get through the weir at Annacotty last year.
For more information, contact the Shannon Regional Fisheries Board, Ashbourne Business Park, Dock Rd., Limerick, ROI.