DOC’s latest fresh water fish survey.

Electric stun fishing does not kill the fish. 

The Department of Conservation’s new threat classification report for fresh water fish 2017 was released in August this year. There are three species that are found in the Mangaiti Stream system that have the “At risk – declining” status; giant kokopu, longfin eel and inanga, .

The giant kokopu (Galaxias argenteus) inhabits the ponding area in the gully below Sexton Road and has been found in the main stream. These tend to be active at night so are rarely seen. It was when Waikato Regional Council’s scientists were doing a fish survey using the electrical stunning method that they were located. Only one giant kokopu was recorded in the stream.

The Longfin eel (Anguilla dieffenbachia) has been mentioned several times on this website. The report noted that the decline in water quality in many areas has resulted in the shortfin eel (which has a “not threatened” status) occupying habitat that formerly held the longfin eel which suggests that the two species may be competing within a habitat or it could be that the longfin eel prefers better water quality. Either way it is clearly evident that the shortfin eel is the dominant species in the Mangaiti waterways. In the 2012 survey there were 2 longfin eel and 21 shortfin eel counted in a fifty metre length of stream. The longfin eel has a very long life and the ones we are seeing appear to be mature adults. The worry is that the population is not being maintained with juveniles moving upstream in their normal life cycle. 

In the 2012 survey, 29 inanga (Galaxias maculatus) were recorded. 

Planting the stream edge becomes all the more important when you are aware of the status of some of the occupants.

Book review

Rat Island: Predators in paradise and the world’s greatest wildlife rescue

By William Stolzenburg

Bloomsbury: 2011

ISBN 978 1 4088 2511 2

William Stolzenburg is an American journalist who writes a lot about animals, but for the past decade, his focus has settled on that particular class of creature called predators. Rat Island is one of three that he has recently published. The other two are: Where the Wild Things Were and Heart of a Lion.

Rat Island focuses on three main island groups; the Aleutians in the Bering Sea, (the group that run south west from Alaska), Clipperton Island which lies one thousand three hundred kilometres off the coast of Mexico and the New Zealand group.

He covers each group with a detailed back history that sets the scene for the full-on attack to eradicate the introduced predators. This is followed up with a description of the recovery of the particular ecosystem or indigenous species that was being targeted.

A large part of the book is focused on New Zealand. The work attempted in Fiordland in the 1880’s by Richard Henry, an early pioneer in pest management, and in the 1960s when Don Merton became actively involved as a junior in the Wild Life Service, all set the scene for the battle to recover Islands that were being decimated by pests. One of the big breakthroughs was the discovery of the single feed bait Brodifacom for the eradication of rats, which are the major pest and the most difficult to eradicate. This replaced warfarin that required high doses delivered over several feeds.

The work done in New Zealand influenced how island sanctuaries around the world managed their eradication programmes. Not all went smoothly. Each island had their unique features that had to be taken into account. There were cases of unexpected collateral damage to manage. Bureaucrats caused frustration then, as they do now. Islands close to urban areas had ill-informed protesters to deal with, but despite this, all had a successful ecological outcome.

The early chapters on the history of the ecological effect of human occupation on Aotearoa, which started seven centuries ago, should I feel, be included in the New Zealand high school history curriculum. We should all understand the ecological damage we have done in the past so that we can better manage the future.

This book is very well written and a really good read. Does it give you hope? I am not sure. Read it and see what you think. 

  

Willow (and Poplar) tree felling in gully

The finishing touches of felling a poplar

The removal of the grey willows from the gully in our restoration area has been a long process. The project was started because of the arrival of the Australian willow aphid in the Waikato a couple of years back. The aphid’s excretion (dew) causes a black mould that completely covers the understorey plants. Coinciding with the aphid’s arrival we experienced a massive population explosion of the German wasps that summer. These wasps feed off the dew from the aphids so the abundance of food may well have been responsible for this population increase. 

We have had a willow poisoning programme running for a couple of years now and this is ongoing.  We were getting concerned that the dead willows along the tracks were falling down and were becoming a safety concern so we applied for, and obtaining funding from Hamilton City Council Community Funding Grant to employ a contractor to fell the trees of concern. This funding has not finished the job so we have obtained further funding from Len Reynolds Trust to finish it off.

Upgrading the grip netting on board walks

With funding from Hamilton City Council Community Funding Grant we have replaced all the non-slip netting on the board walks to a commercial grade. The previous netting was that used to keep leaves out of the gutter on house roofs. While doing this work the boardwalks were also realigned where necessary. After poisoning and cutting down willows the exposure of the boardwalk to the sun has caused some warping.

The Mazda Foundation injects $16,000 into Waikato community projects

Eight Waikato groups, including three environmental groups, have been given donations totalling $16,000 as part of the Mazda Foundation’s latest funding round (they fund New Zealand wide). Our Trust was fortunate enough to receive $4,200 to support our pest eradication programme. This has set up our project on a very sustainable financial footing. Eradicating rats and possums is a crucial part of our aim to achieve a healthy population of indigenous biodiversity within the thirty hectares of the Mangaiti gully system. Mangaiti Gully Restoration Trust is very appreciative of the Mazda Foundation support.