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A fish tale

Mangakotukutuku Stream Care Group’s vision is for a gully rich in native biodiversity and a healthy stream from the headwaters to the Waikato River.


Image - Grant Blackie, Mangakotukutuku Stream Care Group chairpersonSanford Park is where it all started. All the trees and plants you see here have been put in in the last 10 years. Before there were car tyres, shopping trolleys, rubbish; people brought their rubbish and dumped it in here.

Kevin Collier started it all off. He’s an internationally recognised freshwater ecologist. He lives in this catchment, his backyard backs onto the stream. He came down here and checked it out, found some rare fish. This is the best stream in Hamilton city for rare and threatened species. The Mangakotukutuku catchment has the least amount of development at the moment, but that’s still a concern – how future development will impact on the catchment. The whole catchment is about 3000 hectares, and we have 10 or 12 sites where we are doing work.

The biggest focus of our work is to get shade on the stream to protect the ecology. Back in the day, the focus was in taking all the trees away, and the stream was heavily eroded. The stream doesn’t look like much. The muddy colour, it’s mostly natural because it comes out of peat.

A whole corner of the stream has been artificially reconstructed with geotextile bags filled with sand. We have loops of Novaflow at different levels so eels and fish can go in one end and out the other. It’s totally for habitat because this stream has limited plants and woody stuff for them to hide in.

Image - black mudfish

The regional council tagged some fish and monitored them going in and out of a large pipe, recorded how much time they spent in there. They found the pipe got dominated by one large eel and no one else would go in there.

There is a pond created for black mudfish. It doesn’t look like much but it cost about sixty grand. We had to get permits for the mudfish from DOC, and had to get the funds. The pond had to have a clay liner so it wouldn’t drain, and we had to get the mudfish, bring them in. It was kind of historic in that we were bringing species back in to the catchment where they once lived. They did breed but now we have none. We think, when the stream flooded into here, some eels might have got in and cleaned up the mudfish. It is slightly experimental and we will try again.

It’s hard to comprehend how much effort it takes to establish this much vegetation. It’s colossal. There might be 50,000 to 60,000 plants put in here, easy. Five thousand plants a year for 10 years.

We do planting days in winter, and in the summer we have weekly weeding days for a couple of months. We provide the labour and Hamilton City Council provides the plants.

We have an email list of possibly 60 people. On a planting day you might get 20 people. For weeding you might get 10. Weeding is not as much fun, especially on a hot day. The best way to get people to our working bees is to provide beer. So it’s a bit more of a social thing. We have the odd BBQ here after plantings.

Image - Mangakotukutuku Stream Care Group

This gully is just a mess of weeds. Grapes, jasmine, Japanese walnut, convolvulus. You are taking on every weed in the world here. It is a nightmare. It probably looks a bit scrappy and messy to most people but you can spend a lot of time weeding and making it look pretty but the birds don’t care. This time of year the climbing weeds look quite bad, they are at their peak right now. We will do some work and they will die down.

In one area we cut tracks through the blackberry, the council sprayed it, and we got it down to totally bare earth, sowed grass seed to suppress weeds and then planted. It was 100 per cent blackberry, now it’s 100 per cent cabbage trees. That’s small example of what we have done.

Upstream, in the upper catchment, the regional council works with the farmers. We’re talking about four or five kilometres of planting and fencing. This work is on private land and mostly done by contractors.

The whole project has been a collaborative approach with regional council, Hamilton City Council, Tonkin + Taylor, Waikato River Authority, DOC, Waikato Catchment Ecological Enhancement Trust and whoever wants to get involved.

I was bringing my kids down here and they would begrudgingly come along, then they would love coming along, and now they are in their 20s and go “didn’t we plant that stuff over there?” Yeah! And now they have become hooked into all this kind of stuff.

If you don’t do anything you don’t get anything. You might get the odd native tree but, yeah, these gullies are so weedy it’s insane. In fact we almost decided to walk away from this gully because of the effort that’s required.

Image - Mangakotukutuku Stream Care Group