Sea Lamprey (Petromyzon marinus)

Sea lamprey is the largest of the UK and Irish lamprey species, this ectoparasitic species is anadramous; spawning occurs in freshwater rivers and estuaries with individuals migrating and maturing at sea. Spawning requires clean water and gravel and slit or sand is required for the burrowing juvenile stage. Preference for warmer waters. Generally widespread in the UK but is declining in parts of its range. Evidence has shown that sea lamprey are heavily impacted by migratory barriers thus restricting populations to lower river systems. Other threats include pollution and instream works. Fisheries stock surveys in Ireland have reported landlocked populations of sea lampreys at several lakes where individuals are smaller and are opportunistic feeders on large fish species.

• Due to evolutionary histories, sea lampreys have co-evolved alongside their native host species. Thus, water systems with healthy populations of larger fish species such as Atlantic salmon and brown trout coupled with suitable habitats may support sea lamprey populations. In landlocked populations, host fish species include bream, pike and trout.