Dense masses of krill have appeared along the coastline north of Wellington especially along Kāpiti beaches as well as Porirua's Pukerua Bay yesterday and today.
There was also a noticable smell from the dead krill.
Diane Cooper saw masses of the krill at Waikanae Beach.
"Obviously not a regular event as not a seagull in sight to enjoy the feast.
Department of Conservation marine ecosystems technical advisor Emma Hill said, "The volume of krill is likely due to a phyto-plankton bloom in the area, which in turn has created a bloom in zooplankton, which eat phyto-plankton, ie krill.
"There look to be several species involved, the most common one is probably nyctiphanes australis.
"The most likely explanation to them washing up onshore is due to heavy onshore winds or strong currents.
"This is not a common event but it is not unusual.
"There have been mass wash-ups of other marine species around New Zealand.
"In 2013 in Otago, hundreds of bluebottles washed up on the beach due to winds and currents.
"In fact at the end of last year a large number of lobster krill washed up on Tahunanui Beach.
"These occurrences are more common along the West Coast of New Zealand due to the prevailing westerly winds."
On the Kapiti News Facebook page Shekinah Will said the krill would be "good for the garden."
Zac Bowling encouraged a mate to "make some burley bombs".
Trudi Steel said, "I thought it stunk driving home to Kāpiti — now I know."