North Australian FISH FINDER TM forums

I think that it is time for 4 mile billabong to be closed to the general public so that rehabilitation work can be undertaken to remove the salvina weed from the river system.

Controversial no doubt. But watch the video from tales from the tinny and pay particular attention to the final seconds where the boat is and trailer removed from the water. Have a close look at how much salvinia weed is stuck on various parts of the trailer. How much weed is stuck up in the rollers, the springs, the axle bolts, within the channels of the trailer etc?

https://www.youtube.com/watch?v=jfMnlII9Nnc

No matter how vigilant you think you are in removing the weed with so much of it stuck to the trailer it is very unlikely you will detect it all and be able to remove it completely. There may be some people who are capable of it but the reality is most people wouldn't be and others just won't make the effort.

Sometimes our governments and authorities like fishers and parks & wildlife need to make the unpopular decision to protect us from ourselves before we make the situation worse. If left open to the public I believe it is inevitable that the weed will be transferred from here into other places over a short period of time.

Dan.

If a full blown exercise was conducted to removed +90% of the salvina, to a level where the weevil could easily take care of the remaining weed, I'd be happy for a temporary closure. I'd like to think an additional benefit of the closure might be better fishing once re-opened.

Though that would require a considerable amount of time, money and effort that I would suspect the powers that be would deem it not worth their while.

I went there for the first time this year, I've been twice in total actually and each time I have crawled under the trailer to remove all the salvina I could see. I'd like to think that other fishos do as much as they can to remove as much salvina from their boat and trailer as possible.

Bear in mind that Salvinia as it stands exists throughout every billabong in the Magela floodplain in Kakadu and in the early 1980's recreational anglers lost access to numerous billabongs because park authorities though that we would be responsible for spreading salvinia...we still haven't got this access back despite AFANT campaigning for many years.....Salvinia has been spread through the activity of water birds.....and the wet seasons which connects all the billabongs and transfers the weed in water flow.

Closing four mile hole wont prevent the spread of Salvinia........now if you could somehow stop the wet season or prevent birds landing on the billabong and traveling to other water holes that might help.

The main enemy here which needs to be highlighted and worked towards preventing is the aquarium trade and people irresponsibly putting foreign species in our waterways.

AFANT is strongly of the view that Northern Australia must learn from the mistakes of the more populated southern areas of Australia in regards to biosecurity and our waterways principally in regards to the introduction of invasive foreign pest species of fish, plants and reptiles.

The cost of restoring rivers and water ways that have been impacted by invasive pest species amounts to millions of taxpayers’ dollars on individual river systems just to return these rivers and waterways back to some lower level of environmental health. AFANT believes stronger measures for education, prevention and enforcement need to be put in place on the aquarium trade to protect the waterways of the Northern Territory.

If you think salvinia is bad just wait until some irresponsible member of the public decides to release his pet tilapia into your local waterway!!!

I agree with Tristan, once they are closed you'll have to fight like hell to get them back.

The fact that fishos are one of the biggest user groups in Kakadu means little to the park managers, some would probably be happy to see fishos gone.

Look at the West Alligator River, it was closed for studies of an unexploited system (if my memory serves me correctly), as far as I know it was never studied and yet it has not been reopened.

Spot on with your assessment of the West Alligator Matt

Thanks for the background information Tristian. I hear what you are saying and birds and flood waters may be a factor in transferring the weed. With regards to flood waters this would generally only be down stream so the risk of affecting upstream waterways like two mile would be low. I couldn't say for sure what the impact of the birds might be, a smarter man than me may know.

But both of these transport methods would be very unlikely to result in infecting the nearby Mary river floodplain system. A far more likely scenario would be by using a contaminated boat and trailer in fishing in the Mary river after the Wildman. While the concentration of weed around the ramp area is high so is the risk of contamination occurring.

I don't disagree with you on the aquarium issue however I think this is a separate matter.

Dan

Matt Flynn wrote:I agree with Tristan, once they are closed you'll have to fight like hell to get them back.

The fact that fishos are one of the biggest user groups in Kakadu means little to the park managers, some would probably be happy to see fishos gone.

Look at the West Alligator River, it was closed for studies of an unexploited system (if my memory serves me correctly), as far as I know it was never studied and yet it has not been reopened.

This is why we need AFANT to up hold our interests as armature fishermen. A mechanism written into the closure such as an agreed tonne / square km target among other measures could ensure the waterway's closure is temporary.

Regarding the West Alligator I think given that most fishos never had access to the system that this closure does not affect them greatly. In fact further to thatI believe that many of us here actually welcome that the area is set aside to remain pristine provided that the rules apply for all sectors of the fishing industry. This was also reflected in the reef fishing issue by fishermen and AFANT and most people were willing to accept reef closures until learning that a certain sector was exempt from this restriction.

Personally I think some sanctuaries are a good thin and globally we should have a lot more of them. While none of us want to be denied access to somewhere I think we can accept that provided the rules are the same for everyone, regardless of industry, wealth or race then we can accept the law of the land for which the greater majority support because that is the essence of democracy.

Dan

If they do they also should close yellow waters.

Careful what you wish for, I recall a draft management plan for Kakadu several years ago proposed greater restrictions on fishos, but the plan was howled down.

This weed problem could easily become a "fishos are now incompatible with Kakadu park objectives" thing. As stated, the weed can be transferred other ways.

The NT is a big old place, but only a few freshwater hotspots are easily publicly accessible.

OK can't help myself

So AFANT's position is that a closure of 4 mile hole is a waste of time and further more recognises if it get's closed it probably would never get opened again.

and on the other hand

Happily closes down area's for reef fishing to amateurs (commercials are still able to fish there because AFANT can't read fine print) but wan't us all to believe these are short term measures.

It has been about 20 years since I went to 4 mile. But surely a 1 year dry season closure would help get on top of the Salvinia problem.

Methinks the fact that AFANT are made up of the flouro shirt lifters brigade would be harder to get the boys to agree to a closure of Barra water than it was the reef fishing zones.

Rope put across the South Alligator years ago to stop boats was a salvinia control measure, creating a no-go zone. Beats me how it would control the weed given that it floats downstream, perhaps a tiny chance it could become stuck on an outboard leg and moved around.

It floats down the South Alli in clumps during the wet season, haven't heard any calls for all the South to be closed.

AFANT will probably want to close the reef out the front and make it a commercial only zone.
But closing down the river itself would be ridiculous................... there's barra in there you know.

could be wrong but wouldn't the salt water sort salvinia out pretty quickly?

Spot on Dan, that is why two mile hole has less salvinia than four mile hole downstream. I certainty agree fishos need to wash their boats and trailers and remove all weed when they exit four mile hole. I just don't believe closing four mile hole is a solution as Kakadu doesn't have the budget or the inclination to remove the weed physically which is needed to fully clear the system as the weevil is only a moderately effective biological control.

still negotiating with the government on the commercials in the reef fish protection areas so far only trepang, aquarium and the Spanish mackerel fishermen are still allowed in there and we are waiting to hear back from the government regarding the exclusion of the Spanish mackerel fisheries

wouldn't the salt water sort salvinia out pretty quickly?

And there lies the solution, global warming/sea level rise will solve the salvinia problem, everyone needs to relax

The weavils just need a gene mod, send some to Monsanto. They'll come back with bigger mouths and balls, and they'll be Round-up Ready

still negotiating with the government on the commercials in the reef fish protection areas so far only trepang, aquarium and the Spanish mackerel fishermen are still allowed in there and we are waiting to hear back from the government regarding the exclusion of the Spanish mackerel fisheries

Excellent work Tristian! I wish you worked for my company!