Water shows no signs of toxins

Kayakers and dragon boaters may be able to return to the water as soon as tomorrow, but authorities are still some way from pinpointing what made dogs on Auckland beaches ill.

Paul McNabb, technical manager at Nelson science consultants the Cawthron Institute, said tests on water from North Shore beaches near where two dogs died found no well-known species of toxic algae.

Researchers were now carrying out further tests on the dogs' stomach contents - hoping to at least prove that they died from something they ate.

If that happened, health warnings against water sports in the Hauraki Gulf could be lifted.

A health advisory against swimming, fishing, diving and water sports, as well as walking dogs or taking children to the beach, is in place while experts wait for test results.

Results of further tests on the dead dogs are expected this afternoon or tomorrow.

Mr McNabb said if the problem was toxic algae, history showed it was likely to happen again now that the right conditions had arisen.

It was still possible that a malicious poisoner had dropped something on the beach, although there was no evidence of that in the dogs' stomach contents, he said.

Researchers want dog owners to collect the uneaten portion of anything eaten by a dog before it becomes ill for testing.

Mr McNabb acknowledged it might be difficult to get such samples given the health warnings against walking dogs on beaches.

Massey University marine biologist Karen Stockin said it was "very frustrating" not being able to give the public an answer.

Tissue samples from five dolphins that died in the Hauraki Gulf and one from Whangarei had been prepared and would be sent to the Ministry of Agriculture and Forestry for testing today, she said.

She had received reports of dead seals as well as dolphins, penguins and pilchards known to have died.

Dr Stockin said it was more important to get the answer right than to rush and publicise information that might turn out to be incorrect.

Mr McNabb said he did not believe the dog deaths were linked with the deaths of penguins and dolphins.

A North Shore City councillor and member of the Hauraki Gulf Forum, Chris Darby, said it was a shame it had taken the dog deaths to interest people in water quality in the gulf.

"It seems it takes the death of the family pooch to engage people."

Mr Darby said that, whatever the cause turned out to be, the scare highlighted a lack of co-ordination between the different councils and Government agencies.

He pointed to an Environment Waikato report to the Hauraki Gulf Forum - a grouping of Government ministers, tangata whenua and councillors that oversees environmental issues - which said that 3784 tonnes of nitrogen flowed into Hauraki rivers each year, with flow-on effects for shellfish and other marine species.

The same report said the equivalent of 32 truckloads of urea found their way into the southern Firth of Thames each week.

RAT POISON CLEARED

Although rat poison was an early suspect among members of the public, authorities are not blaming it for the deaths of two dogs.

The Ministry of Agriculture and Forestry ruled out Brodifacoum poisoning early on, partly because the dead animals did not show evidence of internal bleeding.

A large dose of Brodifacoum, which the Department of Conservation has been dropping on Rangitoto and Motutapu Islands, could kill a dog but DoC said it would not cause vomiting.

Unlike fast-acting 1080, symptoms of Brodifacoum poisoning in dogs - which can be harmed either by eating baits or from secondary poisoning from eating poisoned animals - show up over a number of days.

The antidote in both dogs and people is vitamin K from a doctor or vet.

A report prepared for the Auckland Regional Council, which authorised the drop, said that at the concentrations dropped over Rangitoto and Motutapu an adult person would need to eat 300 cereal baits laced with Brodifacoum, or approximately a full 20-litre bucket, to ingest a lethal dose. A child would need to eat 100 baits.

Bait dropped in water should disintegrate within a few hours.

The report said Brodifacoum did not dissolve easily in water but residues settled in sediment where they were broken down over a period of weeks.

University scientists said penguins and dolphins that died in the Hauraki Gulf had also shown no signs of internal bleeding.