Hundreds of sea creatures wash up along WA coastline

Over the past few weeks, hundreds of sea creatures have been washing up along parts of the Western Australian coast.

Along the Augusta coastline and lower parts of the Hardy Inlet, a large species of sea hare has been washing up on the shore since at least February 10 this year.

In a statement to Yahoo News Australia, Shire of Augusta Margaret River's coordinator for landcare and environment, John McKinney, said discussions with the state's Department of Biodiversity Conservation and Attractions and residents indicate this is a regular occurrence in late summer.

Though this may be a regular occurrence, the number of sea hares, also known as sea slugs, washing ashore are "higher than before", Mr McKinney said.

Sea hares have been washing up along Western Australia's Augusta coast daily for weeks. Source: Supplied/Shire of Augusta Margaret River
Sea hares have been washing up along Western Australia's Augusta coast daily for weeks. Source: Supplied/Shire of Augusta Margaret River

"Numbers of the animals on the beaches are fluctuating daily with tide, swell and wind conditions, although dying and freshly deceased animals, along with partially decomposed animals appear to be coming ashore every night," he said.

Though the sea hares look rather innocuous, there is concern for dogs in the area.

"The Shire understands that in certain circumstances some species of sea hares can be toxic to dogs and has erected signage at key locations throughout Augusta to advise dog owners to be vigilant," Mr McKinney said.

Removal of the sea hares is not being considered, due to the expansive affected area and the sheer number of them appearing on the beach every day.

It's not just the potentially toxic sea slugs that are causing an issue along the usually pristine coastline - Mr McKinney added there have also been reports of algal blooms.

The Department of Primary Development and Regional Development has collected samples from the water and the sea hares.  Source: Supplied/Shire of Augusta Margaret River
The Department of Primary Development and Regional Development has collected samples from the water and the sea hares. Source: Supplied/Shire of Augusta Margaret River

In recent weeks along the Shire coastline in places like Augusta and Gracetown, there have been reports of what may be a naturally occurring Trichodesmium species.

Mr McKinney said the algae bloom is not believed to be linked to the sea hares, however a combination of the two and seaweed may be responsible for a pungent smell.

"This algal species can produce a very fishy smell when decomposing and it is believed that a combination of decomposing algae, seaweed and potentially sea hares is responsible for a reported smell," he said in the statement.

Department of Health advice issued

WA's Department of Primary Industries and Regional Development (DPIRD) is aware of the situation and an alert states sea hares and water samples have been collected for testing.

"Sea hares and water samples were collected this morning and will be transported to Perth for analysis," the notice said.

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

DPIRD urged people to follow advice from the state's health department.

The Department of Primary Industries and Regional Development is urging people follow general health advice following the influx of sea hares along the coast. Source: Shire of Augusta Margaret River.
The Department of Primary Industries and Regional Development is urging people follow general health advice following the influx of sea hares along the coast. Source: Shire of Augusta Margaret River.

As per the health department's advice, people are being urged:

  • 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.

  • not to allow pets and other animals to come into contact with dead or decomposing fish either in the water or on shore.

In the DPIRD notice, it was advised people should see a doctor if they handled any dead or dying fish and are now experiencing inflammation on their hands around any cuts or abrasions.

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