Starfish massacre on cards

Date published: August 4, 2012 at 5:55 am | Comments

MARAUDING starfish that kill and eat mussels in Ohiwa Harbour could themselves soon be the target of a Ministry of Primary Industries-sanctioned massacre.
The ministry can issue permits to eradicate unwanted aquatic life, such as the predatory starfish which are a recognised problem in the harbour.
In 2009, a Ngati Awa-funded survey conducted by Kura Paul-Burke and Joe Burke estimated the harbour was home to 1.2 million native Coscinasterias muricata starfish – equivalent to a biomass of 672 tonnes.
Three two-year bans have been imposed on harvesting green-lipped mussels from the harbour over recent years to allow stocks to recover, but Ngati Awa Kaitaikitanga manager Beverley Hughes said she worried the closures only provided more food for the starfish.
The most recent mussel ban ended in November 2010.
Mrs Hughes said adult mussels had been “decimated” by sedimentation caused by heavy rainfall events over the past 10 years and their juvenile offspring had been unable to resist the strength of the starfish.
She said the starfish moved “battalion-like” across the harbour, forcing open young mussels, disgorging their stomachs into them and digesting the mussel.
“The starfish are a terrible problem for our harbour. They are a vicious predator and they multiply so very quickly,” she said.
Ngati Awa’s neighbour to the east, Te Upokorehe, promoted eating the starfish as a solution. Once fried, an edible “brown goo”, similar to that found in a crayfish stomach, could be scooped out and eaten.
The daily starfish take limit under normal conditions is 15.
Mrs Hughes said she was pleased the starfish problem had caught the attention of a range of agencies working co-operatively to put a management regime together for Ohiwa.
Ngati Awa was looking into working with an external research group to undertake a research project in January 2013.
David Scranney, spatial allocations manager for the Ministry for Primary Industries, said permits could be issued under Section 97 of the Fisheries Act 1996.
Mr Scranney said a culling applicant would need to design a suitable research project for assessment by the ministry and supply information to support culling.
He said the first proposal in the case of the starfish might be a trial eradication programme.
The ministry was aware of reports elsewhere in the Bay of greater-than-usual starfish abundance, but no scientific survey information was available.
The ministry was aware that in the Coromandel scallop fishery some starfish had been removed in the past when they were recovered as by-catch in trawls.
However, there was no information available to assess the effect of the removal.
Efforts to control starfish worked at Maketu, according to Maketu fisheries officer Harry Ponga.
Mr Ponga said the 11-arm starfish Coscinasterias calamaria, some of them 33 centimetres across, took over the main mussel-growing areas in the harbour but consistent culling efforts overcame them.
Initially, they were cut up and thrown overboard until it was found each piece grew into a new starfish. They were then killed by lethal bleach injection, but this was stopped when it was feared the bleach harmed other aquatic life.
Latterly, the cullers, usually marine studies students from Tauranga, filled sacks and recovered starfish were successfully used to fertilise kumara gardens.
“We got rid of about three or four tonnes. It was a massive operation over three years,” he said.
No take limits had been placed on the cull.
“We just took sacks and sacks of the stuff.”
Sometimes people had been paid a 50 cent bounty for every one they caught.
Mr Ponga said he believed the Maketu starfish were an Oriental variety that arrived in ballast water aboard ships berthing at the Port of Tauranga.
Older people told him starfish were unknown in Maketu waters more than about 15 years ago.
He said the starfish killed juvenile mussels but were not strong enough to kill adults.

Source: Whakatane Beacon