Slender Naiad (Najas flexilis)
Key Details
| Taxonomic Groups: | Vascular plant > flowering plant > Aquatic plant |
| 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: | Najas flexilis |
| UKSI Recommended Authority: | (Willd.) Rostk. & W.L.E.Schmidt |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | in Stroh et al., 2014 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Najas flexilis is thought to be regionally extinct in England having not been recorded from its sole English site, Esthwaite Water, where it was found in 1914 and was last recorded in 1981. The main reason for its demise is thought to have been increasing eutrophication of the lake. Restoration of the lake for both N. flexilis and Hydrilla verticillata would be the key recovery action. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | The only practical conservation measures would be to establish whether it still occurs in Esthwaite Water through underwater surveys and eDNA sampling followed by reintroduction using Scottish material . |
| 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: | No |
| Justification: | This species would not benefit from untargeted management |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 5. Remedial action identified |
| Recovery potential/expectation: | Low - Relict or natural rarity |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Systematic surveys to ascertain its presence at Esthwaite have not been undertaken and so it may persist. |
Key Actions
Key Action 1
Proposed Action: Carry out a detailed underwater macrophyte survey of Esthwaite Water combined with eDNA sampling to establish its presence/absence.
Action targets: 7. Best approach adopted at appropriate scales
Action type: Targeted monitoring
Duration: 1 year
Scale of Implementation: 1 site
High priority sites: Esthwaite Water
Comments:
Key Action 2
Proposed Action: If absent, trial propagation of Scottish material for reintroduction to Esthwaite Water.
Action targets: 6. Recovery solutions trialled
Action type: (Re-)introduction
Duration: >10 years
Scale of Implementation: 1 site
High priority sites: Esthwaite Water
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.