Two men are likely to face court action after being found in possession of 3526 pipi taken from the Ōhiwa Harbour near Kutarere in the Bay of Plenty.
Ministry for Primary Industries spokesman Richard Ratapu said the men were caught with the illegal take during a routine inspection.
He said fishery officers were shocked by the find.
"These men's actions are extremely disappointing. They have shown a complete disregard for the daily legal pipi recreational allowance of 150 per person and have given no thought to the sustainability of Ōhiwa Harbour's pipi stocks.
"A quarter of the pipi were far too small to even consider eating."
Ratapu said it was also concerning the men were local.
"We would expect them to have a greater knowledge of the law, as well as the impact their actions could have on the ability of other pipi gatherers to collect their own legal take."
The pipi were seized and returned immediately to the sea.
Ratapu said the Ōhiwa pipi beds were an important source of kaimoana to the local community and visitors alike, and it was essential everybody played their part in protecting it for future generations.
He said fishery officers closely monitored the area and anyone taking more than their daily limit could expect to be held to account.
To report any suspicious fishing activity, call the MPI 0800 4 POACHER line, 0800 447 6224.