Auckland beachgoers warned to 'be vigilant' and avoid toxic sea slugs this summer

There are several species of sea slugs and only the grey side-gilled species Pleurobranchia maculata is known to be highly poisonous.
There are several species of sea slugs and only the grey side-gilled species Pleurobranchia maculata is known to be highly poisonous. Photo credit: Auckland Council

Auckland Council is warning beachgoers to avoid toxic sea slugs that may make a rare appearance on the city's shores this summer.

While the presence of harmful sea slogs is sporadic, Auckland Council's Alcohol and Environment Health Manager, Mervyn Chetty, is urging people to remain vigilant - particularly while walking the dogs.

Toxic grey side-gilled sea slugs, pleurobranchaea maculata, are native to New Zealand and were linked to the deaths of several dogs on Auckland beaches in 2009.

The dogs had ingested the sea slugs, which contain the poisonous substance tetrodotoxin (TTX).

There has been some recent social media activity around dogs becoming unwell after visiting Orewa and Takapuna Beach in Auckland's northern suburbs, Chetty acknowledged.

"While it hasn’t been confirmed that this is due to the dogs being poisoned by eating toxic sea slugs, it is a timely reminder for people to be vigilant and remain cautious at all times," Chetty said in a statement on Thursday.

"It's a normal occurrence for sea slugs to be washed ashore, but if there's unusually high numbers council will investigate."

Sea slugs should not be touched and any sightings should be reported to the council.

"People can also take a photo and send it to us so our staff can help with identification."

Auckland Council advises the following:

  • sea slugs may be present on any beach and if found should be avoided
  • only the grey side-gilled sea slugs (Pleurobranchaea maculata) are known to contain tetrodotoxin (TTX) and can be highly poisonous
  • do not touch any sea life (dead or alive) found on the beach as it may contain harmful levels of bacteria or be poisonous
  • do not eat anything washed ashore
  • children and pets should be kept under supervision at all times and kept away from any sea life as it may contain harmful levels of bacteria or be poisonous.
  • if you believe someone has come into contact with a sea slug and they start to feel unwell call 111 for emergency assistance immediately.

If you believe a dog has licked or ingested a sea slug, contact your vet immediately. 

Sightings can be reported to Auckland Council on 09 301 0101 or healthenforcement@aucklandcouncil.govt.nz.