Beach-goers strolling along a stretch of our coast earlier this month were treated to a scene of horror as hundreds of birds lay scattered and writhing in pain on the sand, dying by the hundred.
The cause of their grisly death is still yetto be determined, although early testing at Massey University suggests they died as a result of eating contaminated shellfish.
Ministry of Primary Industries Director of Compliance Gary Orr said the recent deaths of the birds and shellfish, found along Waikawa and Kuku beaches, north of Ōtaki, could be linked.
"Initial test results from Massey University and Cawthron Institute suggest that a naturally occurring bacteria may be the cause the shellfish deaths," he said.
"It is possible that the seabird deaths are linked to them eating shellfish contaminated with the bacteria. MPI has advised the District Council and the local health team."
"Final testing is underway, however as a precaution, the Council has erected signs in the area warning the public from eating shellfish. MPI concurs with this advice."
On March 20, Horowhenua District Council posted on its Facebook page a health notice warning people not to eat or gather shellfish in the southern Horowhenua.
"We have been made aware of beached shellfish. While we await to learn from other agencies the cause of this we ask you to take caution," the notice said.
An estimated 100 dead seabirds washed up near Waikawa Beach earlier this month.
"Until further notice please do not collect or consume shellfish dead or alive, or let your dogs scavenge in or near the water between Waikawa Beach, Kuku Beach and Hokio Stream."
In recent years, there were occasions in late summer where thousands of shellfish had died through poisoning due to a naturally occurring toxic algae, and recently there were reports of masses of dead shellfish washing up again.
The most recent bird deaths were consistent with symptoms associated with avian botulism, a naturally occurring toxic poisoning that typically caused paralysis, an inability to fly and a drooping head.
Outbreaks of avian botulism seemed to occur during late summer when there is less oxygen in waterways due to lower water levels.
This caused plant growth to decay creating a microclimate for the toxin to occur.
Meanwhile, there had been numerous incidents of seagull and shellfish deaths on the Kāpiti Coast, and also north towards Horowhenua Beaches in recent years.
February 2015: More than 50 birds, including ducks, seagulls and a shag, were found dead in waterways on the Kāpiti Coast.
The cause of death was thought to have been either avian botulism, which causes paralysis in affected birds, poisoning through cyanobacteria blooms (blue-green algae), or deliberate malicious poisoning.
February 2017: Thousands of shellfish wash up dead on Horowhenua beaches.
