Expert not aware of Yanchep octopus sightings

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There were five separate sightings of blue ringed octopuses on the reef at Yanchep beach in January, according to SLSWA.

WA Museum molluscs curator Lisa Kirkendale says she was not aware there had been five separate sightings of blue ringed octopuses on the reef at Yanchep beach in two days.

Dr Kirkendale hears about one report of a blue ringed octopus sighting each summer on a five year average.

She said she was not aware of a tweet by Surf Life Saving WA  last month, which said there had been five separate sightings of blue ringed octopuses on the reef at Yanchep beach in January.

On Wednesday, January 31 Surf Life Saving WA tweeted a reminder for people to be aware of warnings from lifeguards about blue ringed octopuses.

Then on Friday, February 2 a City of Wanneroo tweet about the sightings said temporary signage had been erected to warn Yanchep beach users.

Dr Kirkendale said she had heard of one sighting in the Swan River  and one at Cottesloe while other sightings were at regional locations this summer.

Although she generally gets to hear about sightings they are not formally reported to her as a matter of protocol and she did not know if they were routinely reported to the Department of Fisheries.

She said while blue ringed octopuses were not aggressive and would typically move away from activity, only biting when provoked their  venom was highly toxic (e.g. LD50 rating of 0.3) and one bite contained enough neurotoxin to paralyse many people.

“The toxins in the venom are produced by bacteria that reside in the salivary glands of the octopus,’’ she said.

“These toxins have evolved not to kill people but are used to subdue prey, including mainly crabs and other crustaceans.

“No deaths have occurred from blue ring octopus bites in the Perth metro area or in WA.

“There have been two deaths from blue ring octopus bites in Australia and these occurred in the 1950s (NT) and 1960s (NSW).’’