Japanese kelp/Wakame (Undaria pinnatifida)

What to look for

  • Frilly sporophyll near base of mature plant.
  • Mature plant only found from early winter to late summer.
  • Strap-like midrib.
  • Smooth thin blades stop well short of base.
  • Generally brown/green.
  • Up to 1m long, sometimes to 3m.


  • Cold temperate ocean waters. Lower intertidal to 20 m depth.
  • Rock, reef and stones, artificial structures and aquaculture equipment. 


  • Can rapidly form dense forests on any available space & overgrows natives.

Current locations 

  • Near-shore habitats along south-east and east coast Tasmania
  • Port Phillip Bay Victoria

What you can do

  • Familiarise yourself with the national best practice management biofouling guidelines for your sector at www.marinepests.gov.au.
  • Inspect & clean niche areas & antifoul your vessels regularly.
  • Clean & dry equipment before transporting & using in a different location.
  • Check anchors & other equipment for tangled algae. . 

More Information

More information on this pest can be found on the National Introduced Marine Pest Information System

Report a sighting

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