This Gold does not Glitter


In today’s podcast we’re wielding a high pressure hose at a Waikato lake – which has become home to the unwanted freshwater gold clam. Lake users are being asked to check, clean and dry anything that touches the water to prevent the spread of the clam to other waterways.


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Kia ora koutou and welcome to Primary Matters, a podcast about the things that matter to Aotearoa New Zealand's primary industries. I'm Carol Stiles.

In May this year, an unwelcome visitor was found in Lake Karapiro, the freshwater gold clam.  It's the first invasive freshwater shellfish to arrive here. We don't want it and we certainly don't want it to spread.

The gold clam can grow in and clog up pipes of power generation, irrigation systems and water treatment plants and can it compete with native species for food and space. Worryingly, it's born fully fertile. It reproduces in huge numbers and creates masses of shells. Biosecurity New Zealand wants to stop that in its tracks.

Hello, I'm Carol.

HM: Hi, how are you going? Welcome to our action stations…

CS: I'm out at Lake Karapiro near Cambridge, where there are waka ama on the water. And Hannah Munro is spreading the word about what we can do to prevent the gold clam establishing anywhere else.

I saw bumper stickers under people’s windscreen wipers.

HM: Yes, I did that this morning, because they all come from different locations; from Rotorua, New Plymouth, Taupo, Tauranga, other freshwater. What we want is to make sure is that whatever we have and use here, we keep here and we don't take those pests and algae and clams and babies and juveniles away into another freshwater system.

CS:  So that's a water blaster.

HM: Yep so, we’re down at Karapiro at the main boat ramp. We've got a wash-down station with a high-pressure hose. So we're all set up here. If you're in using boats or waka or kayaks in Karapiro, there’s a wash-down station that you can come in and make sure you check and clean all your gear before you take it home with you. So the check, clean, dry campaign is to check all your equipment or anything that's been in the water.

So check is the visual. Can you see anything stuck to your equipment that shouldn't be there? Get rid of it. The cleaning is to get rid of the things that maybe you can't see. So for corbicula, the baby clam, it's like a sticky little hair.

CS: Oh, very tiny.

HM: So you might not see it because it might be like a blond little hair, right?

And so if we give that a good blast, we’re going to blow it off, spray it off our equipment. And the dry part of it is to ensure all our equipment is completely dry inside and out, and that limits its lifespan because these are freshwater pests. They survive in freshwater so that when there’s no freshwater they have a limited survival rate, which is what we want.

CS: Today is a good day for drying. It's really hot.

Hm: Yeah, very good day. And also a lot of these waka will be put on the tops of cars or trailers so that’ll give them a good dry as well, as they travel.

CS: Lifejackets. What's the story with those?

HM: Well, because they're absorbent. So these pests live in fresh water. So if you've got a wetsuit or a life jacket that pools water and it is wet, then these babies can survive in them. You know, you take a wet lifejacket home, it's living in your wet life jacket. Same with wet shoes…

CS: Wet shoes?

HM:  Well, yeah. You know, you've you have your sneakers on and you have to go and grab your kid in the lake. You want to make sure that they haven't got a baby corbicula on them. And then you take them home and then you've got them in your drains. So same thing. You know it's anything that touches the water out here.

CS:  So the rules are a little different for shoes, life jackets, wetsuits and togs and towels. Whereas hard surfaces can be blasted and dried, anything absorbent needs treating. It should be soaked in hot tap water for at least 5 minutes. Or you can pop it in a freezer overnight until it's frozen solid. The clams don't like that, nor will they survive if equipment is soaked for an hour in a mix of 10% bleach and water.

HM: But make sure it's completely dry for 48 hours before you use it in another fresh waterway.

CS: That that might be quite difficult in that these guys are training, so they need to get back out on the water.

HM: Correct, yes. So what we advise is to have a couple of lifejackets. So a training lifejacket, where you’re using it in the same waterway all the time.

So this is between waterways. So if you're going to come back to Lake Karapiro to train, that's alright because you're in the same water, you're just coming back into it. But what we don't want is you taking it into another fresh waterway. So we don't want you going from this lake doing an event and then the next day going to train in Taupo or another fresh waterway.

CS: So what sort of feedback have you had from the waka participants?

HM: They are awesome. They all are really passionate about being kaitiaki of the awa and taking good care of it and really compliant and making sure that they're following the rules, right, because we want to keep having events here at Lake Karapiro. And so this is all kind of part of looking after where you've where you are and where you go and leaving it as you found it. They’re awesome.

CS: What's the event today?

HM: Today is a regional event. And so we've got single events today and then we've got the team events tomorrow. So all the way from teenagers up to mature citizens, I like to call them, and it's awesome because they're all working together. We've got these young kids here helping carry up waka for our mature citizens and helping them clean their boats, paddles. It’s been really good.

CS: It looks like it’s quite fun on the end of that water blaster.

HM: Yeah, I do believe that some of them have got a bit territorial over that water-blaster. What they don't probably realize is now the parents are going to be looking at that and thinking you now know how to use a water-blaster and I've got quite a list of jobs for you to do when we get back home!  

And also, we can't use the water from the lake or in the river because that is where the clam is. So you can't just take the water from the lake and clean the stuff that you're using. That doesn't work.

You know, it's clean water pumped down. Yeah.

Cs: (To teenager using high pressure hose) Is it fun to use?

Teenager: It is fun. It's good.

CS: And it's a hot day. So when you get a bit of wind, it blows the mist back on you.

Teenager: Yeah. Yeah, it's good. Keeps you cool.

CS:  So you're doing the waka and also the paddles….

Teenager:  Yeah. Yeah. So we just have to get all the algae off it.  

CS: And everyone's been quite happy with you?

Teenager:  Yeah, yeah, yeah. For sure…

CS: (to man washing a waka) It's quite a good set up, isn’t it, for cleaning them?

Man: Very good.

CS: Did, did you know anything about the clams?

Man:  Yeah, I did actually. They’re worried about them getting into Lake Okataina. There was a story in our local paper, I think.

CS: Where are you from?

Man: Whakatane. Yeah, but this is the first time I've done this. It just because we've come to this event, so I'm not sure if they’ve got anything, any bugs in this lake.

CS: They do.

Man: Oh - they do! They’ve got the clams?  Okay.

CS: So you don't want to take me home with you…

Man: No I don’t!

CS: (to Hannah) A competitor was just asking me if you had clams here. He didn't know that you did.

HM:  Yes, absolutely. Yes. They’ve definitely been found. Twice a year they try to do a lake lowering and they did one in October hoping to find hundreds but found thousands …disappointing.

CS: It's about containment, isn't it?

HM:  So step one is to contain, keep them where they are, stop the spread, and then they can work on a plan. But we have to contain them first.

CS: Well, you've got lots of signage, haven't you?

HM:  Yeah. So everybody should be able to see the message. Check, clean, dry. And I guess we're here as ambassadors just to make sure they understand the message. What is check? Why do we clean? How do we dry? What's the importance of it?

I have spent many, many summers down here with my kids in the lake, rowing on the lake, swimming in the lake and I had never really thought about why we had to clean our equipment. I had never thought about anything living in the river until this came out, when I was like, ‘Oh, of course’, like, how come I never thought of that?

You know, I just saw people taking good care of their equipment. So it's been quite an educational process, I guess, of thinking of that in another way and thinking about what's actually the ecological side of what's happening in Lake Karapiro, how can we protect it so that we make sure that we can continue to swim in the lake, row in the lake, have picnics by the lake and still use it.  

CS: Do you know how widespread the claims are at the moment?

HM: And so the last information I got was that the clam had been found in 94 kilometres of the Waikato River, but not all the way down. So they were in pockets of human activity.

CS: Now, rowing events. There are a lot of those coming up here and hundreds of rowers come, especially for the school events.

HM: Yep, yeah.

CS: So that's going to be another opportunity to get the message out.  But there is a risk, isn't there, that somebody might take this clam back to Ruataniwha.

HM: Absolutely. And I have to say, KRI, Karapiro Rowing Incorporated, who run all the rowing events here, have been absolutely fabulous at enforcing our message of check, clean, dry and the requirements to do it.

They’ve run information sessions via Zoom, every school had to participate and every club had to sign on. The message goes out to all their participants and I've been to 3 events that KRI have run and they have their wash stations down pat. The boats are de-rigged, they are washed, they are on trailers.

The athletes themselves, whether they're high school or adults, know why they have to do it. And so it's really about all these organisations educating their participants and their club members so that they know why they have to do this. Yeah, you know, I don't think it's the big events that are a risk. Everybody that uses the water are a risk and there’s always going to be people that don't want to follow the rules. But if we're all seen to be doing the right thing, then those people that are on the fringe of ‘can't be bothered. Don't know why we're doing it’ are much more likely to do it. So we're kind of hoping for this ripple effect that it's the expectation that this is just what happens when you use Lake Karapiro and that everybody knows the expectation of check, clean, dry, and they do it without even thinking about it.

CS: Because a lot of people will just take their boat out for an afternoon, won't they, just for a little cruise?

HM:  Yeah. And, and we understand that at the end of a day's boating, you know, the kids are screaming and you've got to clean your stuff and you're tired and cranky and you know, you've forgotten to get the tomatoes at the supermarket. So, you know, we get it, but we want to make it’s part of the process of the day of boating and being on Lake Karapiro, that you clean your equipment and you look after the environment.

(Commentary of the waka ama competition)

CS: What have you got here? What have you been carrying?  

HM: These are our boatie keyrings.  So branding awareness, bright yellow, you won't lose them. But also if you drop the keys in the river, they float. So you never lose them…

CS: But if you drop them in this river, you'd have to wash clean and dry it (laughing)!

HM: Check clean dry - yeah check, clean, dry always!  

CS: Hannah Munro.

Biosecurity New Zealand’s working with other organisations to test sites in Waikato, including Taupo, and also in all regions north and south. So far, the gold clam has still only been found along a stretch of the Waikato River. 

It’s not known how the clam came to be here. But scientist estimate it’s been in the river for at least 2 or 3 years.

It’s known to have been spread to other places in the world by on board ballast tanks, through the aquarium trade where the clam’s used to clear water, it has been moved to be a source of food, and it could possibly have arrived on damp water sports gear.

MPI has photos of the clam on its website so you know what to look out for. I'm Carol Stiles and you've been listening to Primary Matters an MPI podcast.

Thanks for joining me.

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