We are a not-for profit organisation established in 2000, whose work is centred around the understanding, conservation and promotion of the estuary’s natural and historical environments.

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Below are brief descriptions of several key invasive species to look out on land around the estuary and its freshwater tributaries. Detailed information sheets can be viewed by following the links.




American Mink (Mustela vison)





  • Originally Introduced in the 1920s, for fur farming
  • Has become established throughout the UK, as a result of escapes and deliberate introductions
  •  Continues to have a significant impact on native wildlife, especially water voles, sea birds and fish on which it predates.




Please report any sightings (along with a photograph), to us at: msep@medway.gov.uk



Asian Hornet (Vespa velutina)


© Jean Haxaire

© Jean Haxaire


  • Not currently present in the UK, but is rapidly spreading throughout France.
  • Very possible that it will reach our shores, through imported plants, flowers, fruit, untreated timber and freight containers.
  • Highly aggressive, its arrival would pose a significant threat to honey bees and other pollinators. Its nests are usually found high up in trees.


Species Alert! Report any sightings as soon as possible to: alert_nonnative@ceh.ac.uk


Factsheet: https://secure.fera.defra.gov.uk/nonnativespecies/factsheet/factsheet.cfm?speciesId=3826



Giant Hogweed (Heracleum mantegazzianum)


© RPS group PLC

© RPS group PLC


  • Easy to identify when fully grown, owing to its enormous size.
  • Usually found on river banks, wasteland and rough pasture
  • contact with the plant must be avoided, as even minute amounts of sap can cause blistering
  • It is an offence under schedule 9 of the Wildlife & Countryside Act to plany or otherwise cause this species to grow in the wild


Please report any sightings (along with a photograph), to us at: msep@medway.gov.uk





Japanese Knotweed (Fallopia japonica)




  • Tall herbaceous perennial with bamboo like stems
  • Commonly found in urban areas on waste land, railways, roadside verges and river banks
  • Removal required by law, if found on development sites


Please report any sightings (along with a photograph) to us at: msep@medway.gov.uk