Island lacks clear vision
Stewart Island is lacking a clear vision for its community’s future, according to a new report commissioned by the Southland District Council.
For the past five months, independent consultant Sandra James has met with 230 of the island’s 380 residents, to help plan for the future growth and sustainability of Stewart Island.
At a Southland District Council meeting last week, James discussed the findings of the report with councillors.
James said while Stewart Islanders were united on the unique environmental and lifestyle qualities of their community, there was a ‘‘lack of strategic leadership’’ for driving the island forward.
‘‘We have 70 community groups on Stewart Island, that’s an awful lot for a community with 400 people.
‘‘That tells me this is a very passionate community, who like to be self-sufficient ... the problem is there is no overview or connection between these groups.’’
James said in discussions with residents, there was a feeling of isolation from the rest of Southland, and a desire to develop more meaningful relationships with external agencies.
While initially James was tasked with developing a long-term community plan, she said it was clear a strong vision for the island’s future needed to be established first.
‘‘Many people believed strategic leadership would allow the community to think about it’s vision for the future and how to get there.
‘‘They said they had been down this path not once but twice before, and there was a reluctance to go into another plan without the right mechanism or supports to connect it.
‘‘I was contracted to develop a plan, but it became very obvious by my second visit that it wasn’t going to happen ... something needs to be done differently to get the plan going and implemented.’’
The report, which was fully funded by the Ministry for Business, Employment, and Innovation, was initially brought about in the wake of the termination of oyster farming on the island in 2017.
James said it had been acknowledged that a change was taking place on the island, with tourism overtaking fishing as the main employer and source of income.
While there were a range of opportunities to explore with regards to tourism, the island had not yet found its niche, James said.
In the report, four key investment priorities were put forward to council.
These included: investigating (when available) technology for an enhanced electricity system for the island.
supporting the next steps of the Predator Free Rakiura project.
improving infrastructure relating to wharves on the island.
the establishment of a Stewart Island Opportunities project to drive strategic development. James said there had been support from the majority of residents to develop a Stewart Island Opportunities project.
In both 1994 and 2011, community planning processes had taken place, with widespread buy-in from people on the island.
Councillor Bruce Ford said while some of the plans developed in previous years had been taken on, there hadn’t been sustained action.
‘‘They sort of fell by the wayside ... some of the topics were picked up, but they lost the driver.
‘‘They’re much more futurefocused now, the previous documents didn’t go far enough [strategically].’’
Councillor Ebel Kremer said the Milford Opportunities model would work well for Stewart Island.
‘‘If you set up a group that is very similar to the Milford Opportunities [project], they will be charged with looking at the strategic overview ... I think it would be a fantastic model.’’
Councillor Paul Duffy said it was a shame some of the work had not been able to be achieved at community board level.
‘‘A lot of this is perfect for the community board, I’ve heard comments the community boards are more focused on services, but the way we should have it organised it’s really not the case.
‘‘There’s an opportunity been lost there, although it’s not irretrievable.’’
When the really large depressions in the sea floor came to light a few years ago, New Zealand scientists were puzzled.
The holes were among the largest recorded in the world and concentrated on the Chatham Rise east of Banks Peninsula.
They’d been discovered accidentally, when a research ship happened to pass over and record their presence, says Jess Hillman, who earned her PhD in marine geophysics at the University of Otago by studying the New Zealand sea floor depressions.
One of the depressions was 11km by 6km and 100m deep. It was big enough to enclose all of Wellington City. Others were only slightly smaller.
What could have caused these unusually large features?
One early theory said they may have been created by meteorites that crashed into Earth eons ago.
Given the size of the depressions, the space object must have been large and the impact probably explosive.
But the depth of the holes and their roughly oblong shape didn’t match conventional space object craters. Water depth, even when sea levels were much lower, also worked against the meteorite theory. It was ruled out.
A second theory proposed that the big depressions were caused by the sudden release of methane gas, a sort of volcano of gas rising quickly from under the sea floor.
In 2010, Bryan Davy of GNS and colleagues calculated that a ‘‘single, sudden release of large amounts of methane’’ from one of the largest depressions would have been equal to about 3 per cent of the current annual global methane release from natural sources.
Three per cent from one event is considerable.
There is evidence that these ‘‘explosions’’ have occurred elsewhere on the planet. ‘‘Massive blow-out craters’’ left behind after methane pops have been found in the Barents Sea off Norway. Craters up to 1km wide are believed to have been created at the end of the last Ice Age.
When ice sheets were present, they put enormous pressure on the sea floor. As the ice retreated, the pressure lessened and the methane built up and formed mounds. These ‘‘abruptly released’’ methane and formed the craters, Norwegian scientists reported in the journal Science.
It should be noted these scientists are talking geological time, Hillman says. The events could have lasted days, months or a year. ‘‘It would be instantaneous on a geological scale,’’ she says in an interview.
Craters and depressions have been observed on continental shelves around the world in the last 15 years or so.
New technology called multi- beam imaging allowed researchers to direct high frequency sound pulses from a ship to the seabed. The sound bounces back to receivers and results in highly detailed maps of the sea floor, says Dr Andrew Gorman, who was Hillman’s PhD supervisor at Otago.
In a 2013 voyage with German and US scientists, Hillman and colleagues got new data and compared the New Zealand sea floor features with those off Norway and elsewhere. They didn’t seem to match.
Some of the New Zealand examples were much larger.
Furthermore, they didn’t find the ejecta – sediments and rocks forced out by an eruption – that would have been expected if there had been a ‘‘sudden’’ expulsion.
They also collected sediment samples and analysed them chemically. They didn’t find the quantities of methane and other substances that were expected if there had been a significant pop.
‘‘Based on the new data we acquired, we can’t find any evidence of methane hydrates in the subsurface that could have caused the depressions to form,’’ says Hillman, who now works for GNS.
OK, so no sudden expulsion. What happened?
In recent months, Hillman, Gorman and colleagues such as Dr Ingo Klaucke of the Geomar Helmholtz-Centre for Ocean Research in Kiel, Germany, have published a suite of scientific papers that seem to solve the mystery.
It turns out the large New Zealand depressions are aligned with the direction of powerful currents flowing across the Chatham Rise.
There are several currents associated with the Subtropical Front, which flow north along the east coast of the South Island, passing Dunedin. When they hit the Chatham Rise – an underwater plateau extending 1400km east from Banks Peninsula – the currents are largely deflected east and northeast.
‘‘Our results reveal a direct correlation between the dominant current flow direction, and the modification and alignment of depressions,’’ reported Hillman and colleagues in a 2018 paper in the NZ Journal of Geology and Geophysics.
In a different paper, Klaucke writes ‘‘the depressions are interpreted as the result of scouring by strong bottom currents’’.
The new papers show the currents are strong enough to displace and carry the kinds of sediments found on the Chatham Rise, Hillman says.
But wait. Currents by themselves probably would not scour an otherwise featureless sea floor, says Hillman. It’s more likely that some initial feature existed that the currents could work on.
There may have been a smaller depression, or ‘‘pockmark’’. Hundreds and perhaps thousands of pockmarks have been found along the east coast of the South Island in recent years. They are typically 10m or 20m across.
They are probably caused by small-scale ‘‘out-gasing’’, says Gorman.
When plants and other biological materials are covered by sediment, they eventually break down into methane and similar compounds. A back garden compost works in a similar manner. These gases rise.
Further out on the Chatham Rise, additional fluids are squeezed out of the seafloor when it gets compacted under more sediments, says Klaucke by email. This is the process described by Davy, but on a smaller scale.
An alternative explanation is that small faults exist under the pockmarks and depressions. Deep fluids and gases rise through the fault and vent at the surface.
The jury is still out on the initiating process, Hillman and Gorman say. More expeditions, probably with a drilling rig ship like the Joides Resolution, would be required.
Nonetheless, mystery mostly solved: The currents did it.