As my previous post shows I have just spent a few days camped out at one of my favourite waterholes in Kakadu, “Four Mile Hole” on the Wildman River. I have had the privilege of being able to have fished this location for more than a decade and holds great memories of great times, great fishing and is a great Northern Territory/Australian natural asset.
On my return to Darwin the local media was awash with reports about “Four Mile Hole” and Salvinia. In today’s climate of media beat-up and sensationalism it is often hard to split fact from fiction so I offer my observations of what I saw during my time camped out and fishing “Four Mile Hole”.
Is there Salvinia at Four Mile Hole?
You bet your life there is. When launching the boat it was evident in clumps along the bank both in the water and on the land where I think it had been pushed up either by the wind or boat wash. On the water immediately, if you looked, small heads of Salvinia could be seen free floating. This was most noticeable when there was minimal wind or wave action.
Was Salvinia there last year?
If it was I did not see it and definitely not as obvious as it is this year. As you progress along the billabong to the area of the still flooded floodplains it becomes obvious as to the extent of the infestation. It is massive with it stretching as far as one can see into the floodplain. I can only assume that the entire system downstream, if not already infested will be in the next flood. Listening to the NT fishing Gurus “Tales from the Tinnie” it was interesting to hear Andy Ralph indicate that park records show Salvinia evident at Four Mile for some years. If this is the case, and I suspect it to be so, why has there been such an explosion this year? Has it reached such a mass where it is unstoppable?? Is it like the grains of wheat and the chess board? Double the grain on each square, easy to start then it gets out of control!
Is it affecting fishing?
Yes and No. I am passionate about fly fishing and enjoy fishing the margins, shallows, lilies and timber structure. These are the areas where Salvinia was most evident and in some areas fishing was not possible. Yes it has affected fishing. For someone trolling or casting deeper waters they may not encounter Salvinia. No it has not affected fishing. Will this be the case next year or the year after??
What does the future hold?
This is the question that should be asked of those that hold the reins of power. One only has to spend five minutes with Mr Google to see that we have a formidable environmental foe in our midst only a short walk for a feral pig, a short flight for a Magpie Goose, a short walk/swim for a croc plus another 101 different ways for it to get to the Mary river system. Then Manton Dam, then Darwin River Dam. Who knows what effect this may have on our water system?
We anglers readily understand the possible impact to our sport in the Mary River system but I think it has the potential to go far further. What impact may it have on the cattle industry that survives on the quality of the flood plains along the Mary. Look at Yellow Waters after the waters recede from the plains there is a thick carpet of Salvinia left. Can the pasture handle this? Can the cattle handle this? So many questions, so few answers!
Again I refer to the “Tales from the Tinnie” where an amount of a million dollars (I stand to be corrected on this statement) was said to being spent by Kakadu on weed control, not Salvinia, all weeds. Obviously the amount of effort is not enough as shown by recent observations/spread. If this is correct I am dismayed at those empowered to look after Kakadu on our behalf. I bet more that that is spent at Parliament House in Canberra mowing the grass and pruning the roses in an area covering a few footy fields not an area larger than a lot of countries.
Where has all these words taken me? I don’t know but the view is good from atop of this soapbox. I don’t what the answer is. I don’t know if there is one. Questions such as these need to be addressed by those of greater intellect and knowledge than I but what I can say is that if we stand by and do nothing things will not improve. I also believe that we have an obligation towards the young mobsters such as the Jack’s, Hayden’s and Brianna’s amongst us.
Myself I am penning a few words to both our Federal and Territory leaders to express my concerns and thoughts and to request information as to actions, if any, they are undertaking to address this problem. As with anything to do politically numbers count. My single letter makes only a very small pile on someone’s desk. A bigger pile gets looked at more. If anyone else has concerns put pen to paper and send it to those that you pay.
My final thought on this subject is that after reading about Salvinia “Good Management rather than Eradication” will be a fantastic and achievable outcome for NT waterways.
Remember, “You’ll never never know, if you never never go.” Get out there and fish.
Tight lines
Jim Churchley
Nice report Jim, ah Salvinia on Four Mile-what a shame, I too must admit that I havent seen it there in the past, mind you I havent been there for many years. The thing with Salvinia though, is that it is reasonably easy to nail. The Howard RIver use to be thick with the stuff. I use to canoe downstream from the Iron bridge on Gunn Pt Rd and some years you couldnt paddle a canoe. Then DPI introduced the Salvinia weavil and it was totally gone in a couple of years.
ReplyDeleteThe stuff is all through KNP, the South is full of it and it comes and goes, you probably noticed it too at Red Lily. I dont really know the recent history of the efficacy of the weavil or if it has even been released in KNP, but I suspect it would have been.
The problem with Salvinia is that is propogates vegetatively. That is one small leaf stuck in a trailer or in a prop exhaust will spread the stuff. No doubt that would be how it got into Four Mile. Everyone who uses the waterways has to be vigilant and make sure they dont have any on their boat, trailer or vehicle when moving between water ways.
As for the budget spent on weed in KNP, I reckon Salvinia is the smallest of our worries. Pasture grasses like Hymenachne and Para grass are doing far more damage to the floodplains. They really do choke out the aquatic ecology so the non-natives like Siamese Fighting Fish can fill the niche. I believe the managers of KNP are well and truely onto the weed situation, the management challenge is now is how to reduce it, I dont think we'll every be rid of it, but we can reduce it and give the natives a fighting chance.
Cheers