The pipi beds in the Ngunguru River are closed after their population has collapsed.
The cockle, cousin of the pipi, is not doing well in that river either.
Last May, thousands of Ngunguru pipi died, and no one knows why.
It's an obvious factor in the pipi decline, measured through Ministry of Primary Industries surveys, which 10 years ago, found about 50 pipi per square metre.
The pipi were 5cm or bigger.
The most recent survey found no pipi bigger than 5cm per square metre.
The variables in the survey would be interesting to know - regardless though, this is an area that has long provided kai moana for locals and visitors.
But it is no longer sustainable.
Pipi reach maturity at about 4cm, and grow to 3cm in their first year.
So any pipi that is 5cm is well over a year old.
Perhaps it is time to revisit the bag limit for pipi - 150 per person per day.
They are small, tasty morsels - you need a large volume for a feed.
And the beds at Ngunguru are easily accessible at low tide. In summer, they get an absolute hammering.
Not everyone takes 150 and the Ministry for Primary Industries checks bag limits but its officers can't be there 24 hours a day.
It has been mentioned that it is something of a mystery as to why the pipi population has declined.
But if you factor in the mass die-off - a proper mystery - last year then the other big factor has to be over-fishing.
It would be naive to think that each person who takes pipi is taking 150 - the factor missing from the equation is greed.
After years of easy access to this edible taonga, we have taken too many.