Urban Possum

A polar blast earlier this year could be the reason a possum made a rare daytime appearance in the central city. A visitor went to see the quake-damaged Christchurch Town Hall when he saw what he thought was a cat in a nearby tree. “I soon realised to my amazement it was a possum,” he said. Landcare Research pest control scientist Janine Duckworth said though possums were not new to the central city, it was rare to see one during the day.

Adapted from a snippet in The Christchurch Press, June 25, 2013


Gorse of the Sea:

The ecology and impact of the invasive kelp Undaria pinnatifida in the Hauraki Gulf

By Kate James, PhD Candidate, Institute of Marine Science, University of Auckland

Undaria pinnatifida is an edible kelp species native to the Japan Sea. In its native range it is commercially grown to produce popular sea vegetable products known as Wakame. Undaria has become established in ten countries outside its native range and has been nominated as one of the one hundred “World’s Worst Invaders” by the International Union for the Conservation of Nature [IUCN]. Undaria has also been named one of the most hazardous seaweeds in Europe and dubbed “the gorse of the sea” here in New Zealand. Since its detection in Wellington in the late 1980s Undaria has become an invasive pest around much of our southern coastlines. Undaria is classified as an Unwanted Organism in New Zealand and is currently the subject of local (experimental) eradication programmes in Fiordland and on the Chatham Islands.

Undaria is a highly adaptable and plastic species which can tolerate a wide set of environmental conditions. It behaves as an opportunistic weed and can rapidly colonise new or disturbed substrata and artificial floating structures such as marinas and marine farms. Undaria is highly fecund, has a fast growth rate and (in New Zealand) multiple reproductive cohorts per year. Undaria can displace and dominate native marine flora during the peak of its growth season. Changes in native community dynamics and trophic food webs occur when native seaweeds are replaced by Undaria and when dense patches of Undaria establish in areas previously devoid of large seaweeds. Undaria can disrupt aquaculture activities and can affect the cultural and recreational (including tourism) values of marine sites. Despite its invasive traits and a desire to keep Undaria out of “high value” marine sites in New Zealand the Ministry of Primary Industries, in 2012, announced three “heavily infested” sites around the South Island where farming of Undaria is to be allowed.

The warmer waters around the upper North Island were thought to be outside the optimal range for Undaria colonisation. But in 2002 Undaria was discovered on mussel farms in the Firth of Thames, in 2004 it was found at Westhaven Marina in the Waitemata Harbour and it has since become well established on both natural and artificial substrata around the Hauraki Gulf. This could mean Undaria farming will be permitted in the Hauraki Gulf in the future.

My work aims to provide a description of the temporal and spatial distribution of Undaria in the Hauraki Gulf as well as gain an understanding of the ecological impacts of its establishment in this warmer region. My survey work has begun to classify the habitats in which Undaria occurs, determine the extent to which Undaria is spreading into natural reef systems (often from mussel farms) and identify the potentially important environmental factors influencing its distribution and spread in the Hauraki Gulf. Undaria population monitoring has been underway since mid-2011 at Westhaven Marina and in the Coromandel Harbour, these studies provide information on the life and reproductive cycles of Undaria on both artificial and natural habitats in this region. Undaria population structure and growth data will be related to local sea surface temperature and seawater nutrient content information and will help identify sites likely to be at risk of Undaria infestation and the potential extent of impacts on ecological and environmental values.

Data on the distribution and biology of Undaria in the Hauraki Gulf is vital if we are to keep marine reserves and conservation sites free of Undaria. This information can also be used to inform policy around the possible commercial farming of Undaria in this region.

I have prepared a report for the Waikato Regional Council which includes some preliminary findings from my work in the Hauraki Gulf. This can be found at:

General information on Undaria can be found on the New Zealand biosecurity website: or on the Global Invasive Species Database at:

Please feel free to contact me for more information on my work or if you have any information on locations where Undaria is growing in the Hauraki Gulf or further north in New Zealand.

Kate James | This e-mail address is being protected from spambots. You need JavaScript enabled to view it | 0212406442

Thank-you to the Waikato Regional Council and the Auckland Council for supporting this research.



Calling all stoats - your flight is about to depart

By Peter Russell

Ferrets, stoats and weasels belong to the mustelid family. All have characteristic long, slim bodies, short legs and sharp pointed faces. The colours of all three animals vary, with generally blackish-brown upper bodies and creamy, white underparts (as opposed to a draft version of the 1996 Waikato Regional Pest Management Strategy, which stated that they had .... creamy white underpants!) So, how do you tell naked mustelids apart? One’s ‘weasily distinguished’, the other, ‘stoatally different’...but you’ll need to ferret out the difference for yourself!

To enable a new research project to start in late 2012, Dr Carolyn (Kim) King from the University of Waikato needed to obtain some captive stoats. She had hoped to purchase freshly captured animals from local trappers and contractors, but that proved to be too difficult. She learnt of a study that had just concluded at Landcare Research at Lincoln using captive stoats for behavioural observations. By January 2013 the project had finished and the stoats were no longer needed. Maintaining them in captivity for no specific purpose was becoming expensive so they were about to be euthanased. Fortunately, Kim heard about this before the deed was done.

Kim was especially keen to buy the Lincoln stoats that would otherwise have no future. Landcare Research for their part were willing to hand them over. But then the question arose, how could they be transported from Lincoln to Hamilton? Driving down to collect them and bring them back, two days each way, was out of the question, and not only because of the expense. Imagine turning up at a motel in Picton, asking for overnight accommodation for two adults and ten stoats.

Fortunately, Landcare knew all about this problem and how to deal with it. When they needed stoats they brought them from trappers around the South Island. A system of secure transport had evolved for them. Each stoat was put in a separate metal carry box with one mesh side, a sliding door, lots of bedding and a chunk of rabbit meat. Three of these boxes fitted into one cardboard box, unmistakably labelled “LIVE ANIMALS”.

Landcare had an arrangement with Air New Zealand for transport of these boxes in the same manner as shipping dogs or cats in carry cages. The stoats cannot see out and people cannot see in, and freak out at the notion of such unusual travelling companions. Landcare were willing to box up the stoats and deliver them to Christchurch airport. The only remaining hurdle was that Waikato University was to pay the air fares. However, the University was rigidly required to buy air tickets through a travel agent in Hamilton .... they had never been asked for air tickets for stoats before! They simply didn’t have a box to tick that their computer would recognise or understand.

In the end, Landcare Research paid the fares themselves and claimed back the costs. Reimbursements, the University could handle. Ten e-tickets for un-named, four-footed, furry passengers with aggressive tendencies, no. With thanks to the Lincoln team, the stoats arrived safely, the research work was done and the results duly submitted for publication. Gladly, they did not live happily ever after, ..... along with badger, moley and rat. Their tickets were strictly one-way.

Epilogue: The stoats were studied to further understand their swimming abilities, particularly finding out how far they might be able to swim. They were quickly put to work and ‘invited’ to swim in long water tanks with currents of water set at various speeds. Their swimming actions, body and paw positioning and stamina were observed, measured and filmed to simulate a made up passage to a fictitious, offshore island teeming with native birds. One female swam non-stop for almost 2 hours in a valiant effort. Swimming is natural to stoats, even their paws are partially webbed to get maximum go-forward in water. Interestingly, Waikato University were keen to use real stoats and fit them with radio tracking collars and trial them under real marine conditions. Alas, DOC red tape meant that idea stayed dead in the water, just like the stoats would have been had they looked like getting away.


Exciting new opportunity for biological control of wasps

By Ronny Groenteman, Landcare research, Lincoln

Wasps are now widespread throughout New Zealand and in some habitats they are among the most common insects encountered. As a result, wasps have detrimental impacts on native ecosystems, economic impacts on our primary industries, give rise to human health issues, and cause disruption to recreational activities.

Current control options do not provide satisfactory relief, and biological control is thought to be a useful option to explore. When successful, biological control provides long-term, cost-effective solution, covering large scales and difficult terrains. This is especially important when the pest is as widespread as wasps are in natural habitats that are vast and impractical to cover by more intensive control methods.

Biological control against wasps in New Zealand was attempted in the late 1980s, but the first agents to be introduced either failed to establish, or produced insufficient levels of control. Although there were other potential agents to explore, the programme was abruptly discontinued.

At Landcare Research we have recently been thinking that the time was right for re-visiting the programme for biological control of wasps. Not surprisingly then, we were excited to hear about the serendipitous discovery of a seemingly devastating mite in wasp nests in New Zealand.

The mite was discovered by Dr Bob Brown, at the time a PhD student. Bob was working on chemical ecology of wasps, as part of a collaboration between Auckland University and Plant & Food Research at Lincoln. He was seriously upset when some wasp colonies he collected for his study started collapsing in the lab. When he examined the wasps under a microscope, he discovered they were heavily infested with mites. The mites were not easy to identify, and are likely to be a new, yet un-described species. An association between such mites and Vespula wasps has never been recorded anywhere.

Who are these mites? Where have they come from? How long have they been in New Zealand? Are they widespread? Do they actually harm wasps, or are they simply hitching a ride? Can they cause wasps colonies to collapse out in the wild as they seem to have done in the lab? Do they only use wasps as their host, or can they transfer to other insects (honeybees, bumble bees, native bees)? These are only some of the important questions we need to explore in order to determine if these mites can be suitable biocontrol agents against wasps. Luckily now that Bob had completed his PhD on wasp chemical ecology, he no longer views the mites as a nuisance, and is excited about the opportunity to explore their beneficial potential.

To be able to assess the mite as a biocontrol agent, the recently-formed community group V-BAG (Vespula Biocontrol Action Group) will be applying to MPI’s Sustainable Farming Fund in November 2013. V-BAG is based at the Top of the South, and currently includes mainly conservation and restoration volunteer groups, along with Nelson and Central Otago winegrowers. Soon, we hope to see more industries (forestry, apiarists) and more regions represented. Sustainable Farming Fund provides grants for projects of up to thre years, and we hope to get this project funded to commence in the coming financial year (July 2014).

We are currently seeking to increase the support base for this project. So, if you would like to find out more please get in touch on: (03) 321 9904 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it .


Auckland Biosecurity forum a success

Contributed by Jenny Taylor, The New Zealand Institute of Agricultural and Horticultural Science

The New Zealand Institute of Agricultural and Horticultural Science held a successful Biosecurity Forum at the University of Auckland in early July with an attendance of 113 people from a range of organisations. The mix of speakers and different viewpoints on biosecurity that were presented did expand our understanding of this topic. Interesting that we did not disagree on the importance of biosecurity but yet there is still room to sort out how best we approach it. The forum did meet the aim of bringing different groups together and promoting discussion and we received feedback that as an independent organisation, NZIAHS was playing a useful role here. "

NZIAHS represents over 600 members covering all aspects of the primary sector including crown research institutes, universities, primary industry companies involved with the meat, wool, dairy, fertiliser and horticultural sectors.

More detail will be available at the NIAHS website at:


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