Alex's Fishing Report 16 June 2016
For those who might have missed it, Four Mile Hole in Kakadu National Park will not be opened this year due to massive infestation with the floating aquatic weed: salvinia.
Apparently, 95% of this iconic lagoon is covered; and although the closure is deemed temporary, don’t hold your breath waiting for it to reopen.
There’s a lot I could write afresh about this, but instead following are extracts from my column published on 17 July 2014:
“One of the Top End’s most-popular inland waterways is Four Mile Hole in Kakadu National Park.
This picturesque lagoon on the Wildman River system opened the weekend before last and, as always, several different groups of anglers went in to test out its fishing quality this year.
Unfortunately this year, what they found was a very sad sight indeed: this iconic waterway has become infested with the dreaded Salvinia molesta.
Salvinia is a noxious floating fern that is native to south-eastern Brazil.
This free-floating plant does not attach to the soil but instead remains buoyant on the water surface.
In some cases, it can be so prolific that it covers a whole lagoon like a blanket, and not much can survive underneath.
I’m told the Salvinia at Four Mile Hole is mainly at the south end, in places right through the lilies and even displacing them, and you can see it well onto the shallow floodplain.
Four Mile is still fishable but in some places it prevents casting to pandanus and semi-submerged timber.
Sadly, it has most likely been introduced to Four Mile by fishermen inadvertently transporting it via boat trailers or landing nets.
That would’ve happened last year or the year before, and no one noticed it until it really took off after the last wet season.
I also understand Kakadu Park weeds and ferals team is aware of the infestation and has incorporated it into its control programs.
Hopefully, it can be controlled so that proper fishing can continue in the lagoon.
However, this infestation raises another major concern: with this noxious plant heading west, the next river system to be invaded can only be the Mary.
Salvinia in Four Mile Hole is a disaster; but if it gets into Corroboree, it will be a catastrophe of epic proportions in terms of the potential damage it can do to recreational fishing in the Top End.
Literally 1000s of local and visiting anglers visit Corroboree each year, and it is the dry season lifeline for a huge, Darwin-based, guided-fishing industry.
Then of course there are all the other waterways along the Mary: Mary River Bridge Lagoon, Hardy’s Lagoon, Alligator and Shady Camp freshwater.
If it does hit the Mary River system, it will have crossed the boundary from Kakadu responsibility to Northern Territory responsibility.
I believe our weeds management people in Government need to be resourced immediately to commence a public relations campaign to make EVERYONE aware of the requirement to not transport Salvinia from Kakadu to NT waterways.
There should be signs along the Arnhem Highway and on the roads that lead to our waterways, advising people of the need to check their equipment.
In the meantime, we need Kakadu Park Management to throw more resources at eradicating this noxious plant in Kakadu.
Thanks to Salvinia, over the decades we have lost many valuable recreational fishing waterways, some steeped in tradition, and we need to reverse the trend and start getting these great fishing spots reopened.
At the same time, we need to ensure that no more waterways get closed.
Perhaps a start might be to establish a joint NT/Kakadu Task Force on Salvinia Eradication and Prevention.
We are talking about a recreational fishing industry worth 100s of millions of dollars to the NT, and a significant chunk of that is thanks to the Mary River system.
Let’s get cracking to fix the Salvinia problem once and for all.
Surely the importance of recreational fishing to the lifestyle of Territorians and as a major economic boost to NT tourism warrant it.”
The only thing that has changed since I wrote that column nearly two years ago is that Four Mile Hole has been eaten alive by salvinia.
It certainly doesn’t look like there was any effort at all to eradicate the noxious plant, or at least to keep it at bay.
I sure can’t see any signs along the Arnhem Highway and on the roads that lead to our waterways, advising people of the need to check their equipment for salvinia transportation.
As for the establishment of a joint NT/Kakadu Task Force on Salvinia Eradication and Prevention, what a dumb-arse idea that was; no one in Kakadu or the NT Public Service took that suggestion seriously.
According to the email flier from Kakadu National Park: “Kakadu will be actively managing the salvinia infestation at Four Mile Hole so that it can be reopened to the public as soon as possible.”
So which part are we managing now? The 5% that is still not covered by salvinia?
To be fair, ongoing disastrous wet seasons have mitigated against the salvinia scourge being flushed down to the salt water where it would die.
Maybe we’ll get an all mother of wet seasons this year, and it will be flushed away.
But is that the “active management” we’re told will happen: pray for a good wet season?
In the meantime, for heaven’s sake, can we be a heck of a lot more proactive about stopping salvinia from traveling from the Wildman River system to the next river system heading west: the mighty Mary?
Mousie of Mousie’s Barra and Bluewater Fishing Charters has done it again: he personally landed this 129cm barra down the Daly River last week.
Darwin’s Natalie Blair traveled to Portland with husband Steve and caught this 83kg southern Bluefin tuna, the biggest fish she has ever caught. The big tuna was carrying two tags, both inserted on 17 January 2007 when it was caught and released in the Great Australian Bight south-west of Ceduna, measuring only 76cm at the time.
The photo of rapidly-spreading salvinia infestation was taken in June last year near the boat-launching area at Four Mile Hole.