Testing to see if the mass death of more than half a million mussels on Northland's west coast may have been caused by biotoxins has come up empty - further supporting the theory that the mussels died as a result of climate change.
Northlander Brandon Ferguson out fishing with his family recently when they discovered hundreds of thousands of dead green lipped mussels at Maunganui Bluff.
It led to Dr Andrew Jeffs, a marine scientist at the University of Auckland, blaming climate change on the mass death.
Jeffs said the mussels died as a result of "heat stress" and warned they may disappear from the region altogether as global warming tightens its grip.
"Yes they've died as a result of the recent hot weather and midday low tides. High pressure systems bringing the hot weather also forces the tide out for longer, exposing the mussels to longer periods of sunshine.