Navigation

On ABC1 tonight
6:08	Country House Revisited
6:57	Clarke And Dawe
7:00	ABC News
7:30	7.30
8:00	Catalyst: Heart Of The Matter
8:32	Redesign My Brain with Todd Sampson
9:32	Fry's Planet Word
10:32	Lateline

STORY ARCHIVE

Sawfish Survival

(27/09/2007)

10:10 mins - Windows media - Real Player

Comments

sawfish Looking like a cross between a shark and a chainsaw, the freshwater sawfish is a bizarre and beautiful top-end predator rapidly disappearing from the world’s tropics.

There are seven species of the sawfish family Pristidae found in Australia, Africa, South America, North America, and South-east Asia. All are listed by the World Conservation Union as critically endangered.

In June this year, nations agreed to ban international trade in sawfish body parts. Some of the main threats to its survival are its fins (highly prized for shark-fin soup) and its toothy snout (which commands high prices as souvenirs).

For the last few years, freshwater biologist Dr Dean Thorburn has been surveying the rivers of Northern Australia to assess our sawfish populations.

“To catch just one in a Northern Territory river is great, but to come to the Kimberley and be able to catch half a dozen is something else”, he says.

The Kimberley in north-western Australia appears to be the world’s last stronghold for the freshwater sawfish Pristis microdon.

In particular, the mighty Fitzroy River is highly important as a nursery for young sawfish before they migrate to the sea to mature.

“It’s the only large river in the region.” Says Dean. “To our south we’ve got a desert, to our north we’ve got a large escarpment. It’s a large freshwater river with a lot of permanent water that’s always connected to the sea.”

All that water has also attracted the attention of irrigators and land developers, and over the decades there have been numerous proposals for dams on the Fitzroy. The latest was in April this year.

Young Aboriginal rangers and freshwater scientists have joined up to form Team Sawfish and discover what this globally significant population needs to survive.

Catalyst’s Mark Horstman meets them for a serious fishing trip on the Fitzroy River – but will the river always be wild enough for sawfish?

TRANSCRIPT

Narration The Fitzroy River of the Kimberley is like the Amazon of Western Australia.

There’s more species of freshwater fish living here than in all the other rivers to the south put together.

So diverse are the fish and so vast the catchment, it’s described by at least eight different Aboriginal languages.

Travis Our language and our culture runs straight through this river, all along the river.

Dr David Morgan To have any sort of success in the Kimberley you really need to involve the traditional owners, and we sort of see it as paramount.

Narration Together they’re chasing the largest fish found in Australian rivers. It’s the freshwater sawfish, or bial bial in the local language.

A cross between a shark, a ray, and a chainsaw, these prehistoric-looking giants can grow to the length of a sailing boat.

Dr Dean Thorburn They are so unique, I think the first time people ever see them, they kind of can’t believe they’re real. But they’re just a very interesting species.

Narration Slow to breed and easily caught, sawfish are critically endangered elsewhere in the world. Only in Western Australia are they protected in both State and Commonwealth waters.

John Watson That’s why we want to try and control some people going, you know and putting dams and all this sort of things in our country, you know.

Narration Big rivers attract big plans to tame them. The first and only dam on the Fitzroy River was opened in 1961, but the plan to grow rice failed.

In the early eighties, a Texan businessman ran bulldozers around the clock to level the dry floodplains for irrigation.

Jack Fletcher The Fitzroy valley is very similar to the Rio Grande valley…the Fitzroy River will flow the same stream flow as the Rio Grande river…if you built a dam at Dimond Gorge, you could produce two crops a year.

Narration More than forty years later, the original dam has fallen into disrepair, its impact on fish life ignored.

That’s what fish scientist David Morgan and the other members of Team Sawfish hope to change.

Dr David Morgan This is a small mesh that we’ve got set for juveniles, because there’s a lot of little guys this year.

Narration Right now, we’re 150 kilometres upstream from the river mouth.

Dr David Morgan There you go, there’s one…freshwater sawfish.

Narration The distinctive snout studded with teeth is called a rostrum. It’s used to find prey in the mud, like a metal detector fitted with a sharp rake.

It’s thought they breed in freshwater, but not until they’re bigger than two-and-a-half metres, and then only small litters every few years.

Dr David Morgan This is a classic example of why they’re rare throughout the world. They get caught in any kind of mesh sizes.

Narration Baby sawfish are half a metre long when they hatch inside the mother, their teeth encased in a protective sheath.

Dr David Morgan 18 left teeth, Jeff… rostrum length is 225…total length, 90cm on the dot.

Narration That means this one’s about a year old. More than one hundred have now been tagged, from the coast to 400 kilometres inland.

Even though they’re predators at the top of the food chain, surprisingly little is known about them.

Dr Dean Thorburn We know there’s four species in Australia. A lot of their biology is still not understood. A lot of their genetics isn’t understood and we’re still not fully aware of their distributions.

Narration But one thing is clear: the Fitzroy River is Sawfish Central. This may be the world’s last stronghold for the freshwater sawfish.

Dr Dean Thorburn We’re not sure why the river has the numbers that it does. In the river we get them up to about 2.8 metres, all of which are immature. But they do get up to 7 metres out in the salt.

We’ve recognised this as a really important area. They have been wiped out from a lot of places in the world, and we’ve found now a population that’s sustainable and large enough, and essentially that’s what we’re trying to do to protect it and keep it.

Dr David Morgan This one we tagged a couple of years ago, I’m not sure where yet, but 7021 is the tag, it’s a female.

Narration By attaching transmitters to the sawfish and anchoring receivers along the river, the sawfish can record their depth, temperature and location whenever they swim past, like e-tags on a tollway.

Dr Dean Thorburn When we come back and hook up the laptop we can actually see where that fish has been and what he’s been doing during the day and night in the tides and essentially how far upstream he’ll travel. It’s a lot easier than us being out here every day trying to net them.

Mark Horstman Has this been done up here before?

Dr Dean Thorburn It’s not been done on sawfish…it’s the first one that’s been used in a river, especially a tropical river.
Narration The idea of camping on a wild river to save an endangered species sounds glamorous – but it takes hard work around the clock.

Dr David Morgan Well, as you can see, I probably haven’t showered for about five days and yeah it’s tiring, very tiring. Particularly, it’s cold now too so, I mean when it heats up there’s a lot more things like catfish and barramundi and crocodiles in the nets so it’s fairly constant, just to try and make sure everything survives.

Narration The nets are checked every couple of hours a day, from dawn until midnight. They also sample what the sawfish are eating.

Dr David Morgan A lot of the larger fish like barramundi and sawfish come in to the shallows to feed at night and this is why.

Narration Doing their fair share are three teenagers from the nearby community of Jarlmadangah. They’re Yiriman rangers, part of a youth project devised by their elders to keep kids out of trouble.

John Watson If we don’t teach them the way that we was brought up, otherwise they’re never going to know nothing, you know.

Josh More better to come out bush, looking after your land.

Mark Horstman So its something you want to stick with, you reckon?

All Yeah, yeah.

Mark Horstman You’ve been catching a lot of small sawfish around here, what is that telling you?

Dr David Morgan Oh it’s telling us that it’s great. Although it’s an endangered species worldwide, you tell people up here and they go “oh, there’s plenty of sawfish”.

This year I think we’ve caught, including recaptures, something like thirty juveniles, which is really encouraging.

It’s been a really good sustained wet, not such a big wet but a long wet. And, and I really think that’s probably why we’re seeing so many.

Narration The river is such an important nursery for sawfish because long stretches remain connected to the sea throughout the year – from massive floods in the wet season, to a chain of pools in the dry, like now.

Mark Horstman To try to get a sense of how much water flows down the Fitzroy River takes a bit of a climb at this time of year. In terms of discharge, this river is one of the biggest in Australia. That’s because it drains around about a third of the entire area of the Kimberley, and this is where it gets to in the wet season.

Narration Out of this single river flows more than four times the entire amount of water that all of WA uses in a year. This watery El Dorado hasn’t escaped the attention of politicians in thirsty Perth.

Earlier this year, the WA Opposition leader proposed a 2000 kilometre pipeline from the Kimberley to the south.

Hon Paul Omodei MLA Part of that proposal will be to create a dam on the Fitzroy River, and create a new industry, and turn the Kimberley into the foodbowl of Australia.

Mark Horstman Let’s just say the Premier said, “Dr David Morgan, we want to put a dam on the Fitzroy”. What would you advise him?

Dr David Morgan Well honestly I would, I’d totally advise against it, yeah I would just say look, you know there’s other rivers that are dammed, I would really look at leaving this alone.

Narration David hopes we can learn from the old dam that’s already here.

Dr David Morgan It’s a huge barrier to fish migration and fish migration is everything in this river, fresh water sawfish, barramundi, different species of mullet and a number of others, bull sharks move up the river and then they hit this.
Effectively for nine months of the year, in most years, it’s a barrier. Fish can only get over it for three months of the year.
This is the only thing stopping fish moving at least four to five hundred kilometres up river.

Narration The scientists recommend removing the old dam, or at least building a fishway around it. Senior traditional owner John Watson is a little more direct.

John Watson I always say to the Yiriman workers that if they find me a box of dynamite, I’d like to blow that up. You know I’ve been a powder-monkey in my time, so that’ll be easily done by me.

Narration For the Yiriman rangers like Travis, the research has changed his life more than he expected.

Travis Probably get sent down to Murdoch University and get more training.

Mark Horstman So by working on this, it’s making you think you might go to uni and study science?

Travis Yeah.

Mark Horstman Were you thinking like that before?

Travis No.

Mark Horstman That’s a pretty big change.

Travis Yeah.