Scientists trying to breed toxic slugs

Photo / Janna Dixon

Scientists are trying to breed toxic sea slugs found alive on Auckland beaches to find out whether they pass their toxins to their offspring.

Tetrodotoxin - a potent neurotoxin - in sea slugs is believed to have killed five dogs and made at least 13 ill, three in the past week.

Scientists do not know how the toxin, known as TTX and found in the vomit of one of the dead dogs, got into the sea slugs that were found on Cheltenham and Narrow Neck beaches in Devonport.

Paul McNabb, technical manager at the independent Cawthron Institute science research centre, said if they could figure out how to breed the slugs in captivity they would find out whether the baby slugs were toxic, or whether the slugs had had to eat something in the environment to become poisonous.

Mr McNabb said little was known about the slugs - Pleurobranchaea maculata - because they had only just been found to be poisonous.

"We know they are spawning at the moment, probably in the shallows and ... sandy areas of Narrow Neck and Cheltenham."

He said it was not known why they might prefer Narrow Neck and Cheltenham, or whether they were spawning more than usual in that area.

Slugs from North Shore beaches had been flown to the Cawthron Institute in Nelson and were being kept in an aquarium, he said.

The next step was to figure out what they ate and how to grow them from eggs.

Auckland Regional Council staff combed Takapuna, Narrow Neck and Cheltenham beaches late last week but did not find any more slugs.

An Auckland Regional Council spokesman said council staff would be back looking for slugs on the beaches today.

North Shore residents say people have recently begun to return to the beaches after the spate of dog poisonings sparked a health alert in July.

But three more dogs became sick - one dog after walking on Narrow Neck beach and two more after walking on Takapuna beach - last Tuesday.

The Auckland Regional Council, which is co-ordinating the efforts to manage the poisonings by Government agencies and councils, said no further deaths or illnesses had been reported since then.

A fourth dog is understood to have been reported ill after walking on a Remuera reserve but its symptoms did not match TTX poisoning.

Owners of dogs believed to have died or become ill with TTX reported their pets staggering, losing control of their limbs, vomiting and frothing at the mouth.

North Shore City Council spokeswoman Kelly Gunn said signs with pictures of the poisonous sea slug would stay up at North Shore beaches, with a warning to closely watch dogs and children.

She said dogs should not be walked off the leash and should not be allowed to lick anything on the ground.