Shellfish ban to be placed on coastline

A shellfish ban is in place at Ngunguru Estuary

A rahui on gathering shellfish will soon be placed on Ngunguru Estuary following the second mysterious mass die-off on Whangarei's coastline, and tangata whenua want Government backing to enforce the ban.

Though the sudden deaths in May had put the spotlight on the fishery, there had been concerns about over-harvesting in the area for much longer, said Ngunguru marae trustee Paulette Wellington.

A spokeswoman for the Ministry for Primary Industries (MPI) said the cause of the die-off was not clear, though a "rickettsia-type" bacteria had been found in the dead pipi. The exact number that died was also unclear, but witnesses at the time said it appeared a large number had perished over the course of a day and that the estuary area smelled strongly of rotting seafood.

MPI confirmed this, and said another mass die-off was plausible, although the bacteria was common and not normally associated with mass deaths.

"There could be another mortality event. We just don't know how likely this is or what other factors " such as stress on the animals " may have played a part in what happened," the spokeswoman said.

MPI had also investigated the decline in numbers of shellfish at Ruakaka's Mair Bank following reports the population there had crashed, but did not find any bacteria or pathogens.

"Due to the timing of when MPI was called in to investigate, it is difficult to tell if what occurred [at Mair Bank] was as the result of a single event (like Ngunguru) or whether it had been a gradual decline," the spokeswoman said.

Ms Wellington said marae trustees had requested MPI carry out a survey on shellfish stock at Ngunguru Estuary more than 18 months ago. Results from a late-2014 survey were still pending and were now probably largely irrelevant following the die-off, she said. A health-related ban on gathering pipi at Ngunguru was lifted recently, as the bacteria was host-specific and was not dangerous to humans. Ms Wellington said she believed MPI would place its own ban on gathering, though hapu would be placing a rahui on the area for the foreseeable future regardless, to give the population a chance to replenish itself.

The spokeswoman would not confirm an official ban as yet, but said MPI was "looking at potential options to remove any pressure from fishing that could exacerbate the decline".

A rahui was a form of tapu restricting access to a particular resource.