The sea lamprey Petromyzon marinus (Linnaeus) is both an invasive non-native species in the Laurentian Great Lakes of North America and an imperiled species in much of its native range in North America and Europe. To compare and contrast how understanding of population ecology is useful for control programs in the Great Lakes and restoration programs in Europe, we review current understanding of the population ecology of the sea lamprey in its native and introduced range. Some attributes of sea lamprey population ecology are particularly useful for both control programs in the Great Lakes and restoration programs in the native range. First, traps within fish ladders are beneficial for removing sea lampreys in Great Lakes streams and passing sea lampreys in the native range. Second, attractants and repellants are suitable for luring sea lampreys into traps for control in the Great Lakes and guiding sea lamprey passage for conservation in the native range. Third, assessment methods used for targeting sea lamprey control in the Great Lakes are useful for targeting habitat protection in the native range. Last, assessment methods used to quantify numbers of all life stages of sea lampreys would be appropriate for measuring success of control in the Great Lakes and success of conservation in the native range.

The 3 lamprey species, sea lamprey Petromyzon marinus L., European river lamprey Lampetra fluviatilis L. and European brook lamprey L. planeri Bloch, that inhabit the Iberian Peninsula are of conservation concern. They are considered either Vulnerable, Critically Endangered, and even Extinct in different regions of this area mainly due to habitat loss and population fragmentation. Although several other factors contribute to the decline of lamprey populations in Iberian rivers, obstacles to migration (dams and weirs) are probably the most widespread and significant, causing an estimated 80% loss of accessible habitat in most river basins. We analysed historical records from all main Iberian rivers before the construction of impassable dams became widespread, and found that lampreys were consistently present in the upper reaches. The un - blocking of the lower stretches of major river basins and the restoration of former spawning sites and larval habitats should be considered as priority measures for the conservation of these species. Identification of Special Areas of Conservation to be included in the Natura 2000 European network can also be very relevant for lamprey conservation