Sea Lamprey (Petromyzon marinus)
Key Details
| Taxonomic Groups: | Vertebrate > jawless fish (Agnatha) > Fish |
| Red List Status: | Least Concern (Not Relevant) [LC(nr)] |
| D5 Status: | Included in the baseline Red List Index for England (Wilkins, Wilson & Brown, 2022) |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | (none) |
| UKSI Recommended Name: | Petromyzon marinus |
| UKSI Recommended Authority: | Linnaeus, 1758 |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Nunn et al., 2023 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Population has undergone severe historic decline and current populations are well below their favourable conservation status. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Species is poorly represented in current monitoring programmes and historic fish passage solutions may not be suitable. This species is subject to a range of pressures including barriers to migration, water quality and physical habitat loss. They also require bespoke monitoring programmes which are not currently in place and there are significant knowledge gaps in their ecology. If sea lamprey are to achieve favourable conservation status significant and often bespoke restoration actions will be required. |
| Question 3: | At a landscape scale, would the species benefit from untargeted habitat management to increase habitat mosaics, structural diversity, or particular successional stages? |
| Response: | Yes |
| Justification: | Sea lamprey need a mosaic of habitats in freshwater - gravel to spawn, sediment for ammocoetes, possibly also complex structure (e.g., tree roots) as refugia for upstream migrating spawners. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 2. Biological status assessment exists |
| Recovery potential/expectation: | Low - Combination or other (detail in comments) |
| National Monitoring Resource: | Combination - insufficient |
| Species Comments: | Impacted by barriers to migration and pollution. The species specific nature of lamprey passage needs to be recognised so as not to preclude options for lampreys when implementing solutions for e.g., salmonids. Sea lamprey are vulnerable to entrainment in abstractions (unless mitigated by screening), particularly during transformer and early marine stages. |
Key Actions
Key Action 1
Proposed Action: Undertake prioritised and targeted barrier removal or easement to deliver longitudinal connectivity across freshwater habitats and unhindered migratory passage for sea lamprey.
Action targets: 7. Best approach adopted at appropriate scales
Action type: Pressure mitigation
Duration: 6-10 years
Scale of Implementation: National
High priority sites:
Comments:
Key Action 2
Proposed Action: Deliver suitable monitoring programmes and techniques to assess lamprey populations.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: >10 years
Scale of Implementation: National
High priority sites:
Comments: Sea lamprey ammocoetes are notoriously difficult to find, time and resource may need to be spent developing survey methods.
Key Action 3
Proposed Action: Undertake research to better understand lamprey ecology, particularly marine distribution of anadromous lampreys, and deliver new monitoring and restoration techniques.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 2 years
Scale of Implementation: National
High priority sites:
Comments:
Acknowledgment:
Data used on this website are adapted from Threatened species recovery actions 2025 baseline (JP065): Technical report and spreadsheet user guide (Natural England, 2025). Available here.