Swan River Algal Bloom

Alexandrium Bloom

Following two consecutive years of significant Alexandrium blooms impacting recreational and commercial fishing in the Swan and Canning Rivers, the Department of Primary Industries and Regional Development (DPIRD), Department of Biodiversity, Conservation and Attractions (DBCA) and the Department of Health (DoH) have decided on a new management approach.

The new approach involves the installation of caution signage at various locations around the river advising against eating mussels or crab viscera/stomach.

An example of this signage is below:


Caution signs have been placed at the following locations:

  • Claughton Reserve jetty
  • Hinds Reserve jetty
  • Katanning Street jetty
  • Memorial Drive boat ramp;
  • Bath Reserve foreshore and jetty
  • East Street Maylands Yatch Club and
  • Maylands boat ramp.

Please see the Department of Biodiversity, Conservation and Attractions website for further information and updates. 

Karlodinium Bloom

The Department of Biodiversity, Conservation and Attractions (DBCA) advises that elevated levels of harmful algae (Karlodinium spp) have been detected in the Swan River.

The algae, which can cause a reddish-brown water discolouration, is primarily occurring between Matagarup and Guildford Road Bridges in the Swan River. The algae can produce toxins that can impact fish by damaging their gills and in severe cases, may cause fish deaths. Blooms of this algae can also produce a ‘fishy’ odour.

This week’s forecast for warm weather could assist this algal bloom to proliferate. DBCA officers are continuing to monitor the bloom and will keep our key Riverpark stakeholders updated.

Information from members of the public is welcome. Anyone who sees dead or sluggish fish in the Swan River are asked to report this to FishWatch on 1800 815 507.

The public is also advised to not collect dead fish and to prevent their dogs from consuming dead animals that may appear along the river foreshore. Whilst this alga is not known to impact human health, the Department of Health recommends that people avoid swimming in water that looks discoloured, murky or smells unpleasant.

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