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Government of Western Australia - Department of Fisheries
Wednesday 17 March 2021

Update to Fish Kill NOTIFICATION – Hardy Inlet, Augusta

UPDATE to Fish Kill Notification
- 17 March, 2021 at 4.10pm

The Department of Primary Industries and Regional Development (DPIRD) has concluded its investigations into the recent fish kill in the Hardy Inlet at Augusta.

Thousands of giant sea hares, Aplysia gigantea, have washed up in the area since early February.

Sea hares mate during summer and early autumn.  They are hermaphrodites and often mate in numbers from two to around 20 individuals.

Compliance officers from DPIRD collected sea hares and water samples last week, which underwent analysis in Perth.

Test results showed very little algae in the water samples. Results from our analysis of sea hare samples indicated the presence of a bacterium species Vibrio harveyi.

Vibrio harveyi occurs naturally in marine habitats and is a well-recognised cause of disease in a range of wild and cultured aquatic vertebrate and invertebrate animals. This bacterium is highly likely to have been opportunistic in this event, with serious infections arising primarily in stressed animals; this could have occurred in conjunction with the sea hares’ mating season and possibly other environmental factors.

No further sea hares have washed up dead today and the event appears to have largely passed.

Monitoring of the current situation will continue over the next few days.

If further information is available, there will be further updates. In the meantime, we again remind people to stay safe around fish kills by following the general Department of Health advice.

Fish Kill Notification
- 10 March, 2021

Officers from the Department of Primary Industries and Regional Development (DPIRD) are responding to reports of a fish kill in the Hardy Inlet at Augusta. 

The reports indicate hundreds of sea hares, also known as sea slugs, have washed up in the area over the last two to three weeks.

Sea hares and water samples were collected this morning and will be transported to Perth for analysis.

Updates will be issued when further information is available. In the mean-time, people are reminded to stay safe around fish kills.

We urge people to follow the general Department of Health advice:

  • not to swim in areas of water with large numbers of dead and decomposing fish because they may contain high levels of bacteria and have an objectionable odour;
  • not to fish in water with large numbers of dead fish;
  • not to handle, collect, relocate or use dead fish for bait or consumption because of the risk of high levels of bacteria, and the potential for infection through handling or ingestion; and
  • not to allow pets and other animals to come into contact with dead or decomposing fish either in the water or on shore.

Anyone who has handled dead or dying fish and experiences any inflammation on their hands around any cuts or abrasions should see a doctor. 

Fish kills should be reported to our FishWatch 24-hour hotline on 1800 815 507.


DPIRD’s laboratories carry out testing of any fish samples assessed as suitable for that purpose. This can take some time and it may not be possible to identify a single definitive cause, but every effort is made to establish probable factors. 

More information on fish kills can be found on the Fisheries website at

PHOTO CAPTION:  Sea hares near Colourpatch, Hardy Inlet, Augusta (photo credit: Shire of Augusta-Margaret River)

Last modified: 17/03/2021 4:15 PM

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