| Home » Fisheries Research and Development » Lamprey conservation and management »
Sea lamprey (Petromyzon marinus)
The sea lamprey, Petromyzon marinus, is the largest of the Irish lamprey species. It may reach a length greater than 70cm but average fish measure 50cm. This lamprey tends to favour larger rivers (>30m across) for spawning. Petromyzon follows a similar reproductive strategy to the Lampetra species. However, they tend not to migrate as far up the rivers and often spawn slightly above estuarine waters. Due to their larger size, they are capable of moving quite large rocks to construct their spawning nest or redd. Therefore, they are not restricted by the size of bed material but still must have clean fast-flowing waters. This species spawns during the summertime and young sea lamprey stay in muddy sediment for a number of years.
Sea lampreys are found on both sides of the Atlantic. Whilst this species is protected by the EU Habitats Directive (Annex II), it is considered a pest species in North America. This species migrated into the Great Lakes ecosystem with the construction of canals linking each lake for shipping.
A large proportion of these sea lampreys then became resident in the lakes. Lake trout fishing has traditionally formed a major part of the economy in this region. However, sea lampreys have been blamed for reducing the numbers of lake trout through parasitizing and often killing catch-able fish. Therefore, for the last fifty years a major effort has been made to control the number of sea lamprey in this catchment. Some success has been achieved but sea lamprey are still managed and eradicated in these lakes.
In Ireland, habitats suitable for lampreys are monitored and managed in accordance with EU law to conserve the native population of sea lamprey. However, sea and river lamprey pose no threat to freshwater fish in Irish waters since most of their feeding is upon weakened or diseased marine fish.
Next: Kilkenny
Flood Relief Scheme
Previous: River
lamprey (Lampetra fluviatilis)
