Trust chairwoman Tina Mason told stuff.co.nz that spreading ashes around kai area was "unheard of" and had upset locals in the coastal Taranaki area.
She said neither the trust nor mana whenua were told prior to the ashes being scattered.
The ban on collecting kaimoana and onshore fishing has been put in place until further notice.
Signs have been erected within the affected area informing people about the ban.
Mason said the trust would be making contact with the Ministry for Primary Industries about the incident.
The trust has been contacted by the Herald for comments.