Marine deaths unexplained
The mysterious deaths of sea creatures in Rodney and further south on the North Shore may be from a combination of factors.
Thousands of pilchards washed up at Martins Bay, Stanmore Bay, Orewa and Long Bay.
A disease or virus similar to the herpes virus that killed off huge numbers of the fish in 1995 may be to blame. This virus could have come into the country then in dead pilchards imported as fish bait.
Now there have been higher than usual numbers of dead dolphins, penguins, gannets and other sea birds in the Hauraki Gulf reported during July.
About 14 little blue penguins out of nearly 20 handed to "the bird lady" Sylvia Durrant during the past few months have died, probably from starvation. Nearly all were underweight – some losing more than half their normal body weight – and suffering gastro intestinal bleeding.
Rather than poisoning, Sylvia puts the bleeding down to the penguins’ strong digestive juices having nothing to work on except the stomach and intestinal lining.
"They have powerful digestive juices to break down fish bones and scales, so the juices can cause intestinal ulcers."
The sickly penguins were placed on heated pads and fed at her SPCA Bird Wing centre in Rothesay Bay, but many were already too far gone. Of the six survivors, one was due to be released at Manly this week.
Tests are being done to determine the cause of the penguin deaths, but Sylvia believes it’s likely to be a result of starvation through food shortages rather than toxins.
Autopsies of two dead little blue penguins from this area by Massey University vets in Palmerston North confirm they were malnourished.
Pilchards are part of the gannets’ and little blue penguins’ diets. The penguin population was also hit after the 1995 pilchard herpes episode.
While not wishing to be drawn on possible causes, Massey University marine biology researcher and dolphin expert Karen Stockin says there have been six common dolphin deaths in the Hauraki Gulf between July 7 and 30 which is higher than usual for this time of year. She is confident two died from drowning in set nets with the other four autopsies being inconclusive.
Most dolphin deaths happen in spring and early summer, she says. They often relate to the birth of young dolphins, with fatalities often involving stillbirths and young animals becoming separated
from their mothers.
Meanwhile, the Auckland Regional Public Health Service is strongly recommending people avoid contact with the sea, sea life, avoid exercising pets along the beaches, keep children away from the beaches and not to collect shellfish after two dogs died from suspected poisoning on North Shore City beaches
Julie Haskell, the owner of a third which survived, noticed her black labrador Guss acting strangely after a walk on Waiake Beach. He was ill within hours and a vet says the dog’s neurotoxin poisoning could well have come from eating a puffer fish.
The dog poisoning only appears to be south of Rodney, with vets contacted in Wellsford, Warkworth, Orewa and Whangaparaoa saying they have had no reports of dogs getting sick after beach walks in Rodney, in spite of large numbers of dead pilchards washing up on some Rodney beaches during July.
The Rodney District Council is monitoring the situation but has not issued any warnings at this stage.
While speculation is rife on possible causes of the pilchard deaths, a lack of fresh fish samples is making it hard for Biosecurity New Zealand to figure out what is going on.
"These fish start to deteriorate very quickly and the results of tests so far have been inconclusive because of it," says animal response team senior adviser Naya Brangenberg.
They want people who find dead fish or birds to put them on ice immediately – away from human food – and call the biosecurity hotline 0800-809-966.
They have kits ready to be sent out so samples can be delivered at no charge to their laboratories in Palmerston North as soon as possible.