Drum lines are a work around that's not going to work over time, we need to deal with the root cause (yes it nerds ITIL). The root cause to big sharks coming in and eating people are there isn't enough food out deep for them. Let's fix the root cause and build artificial reefs for fish to live in. We have no real ground in the metro area, so lets build artificial reefs and not let anyone fish them for 5 - 10 years. Even replenish the reef with fish like kingfish, CSS is having a great new record in breading fish (kingfish). Let's build homes for fish and replenish the fish stock. If the sharks have food out there, then they don't need to come in and eat us. The drum lines will do one thing which as a temporary measure, which will reduce the big fish, which will reduce the competition for food. But if we don't deal with the root cause and we keep over fishing, this problem is only going to get worse. I started kiting last year because I can kite when it's too windy to fish and there isn't the fish out there of 10 years ago. We over use all of our natural resources.
If we really want to be real let's force the government to spend the cash now, build the habitat and populate it. Stop anyone fishing them and the fish will over populate these reefs and move to the natural reefs, it's a win win for everyone

Not even sure where to begin with this ridiculous post.

Firstly, on what evidence do you base your hypothesis that the root cause of big shark attacks is a lack of food out deep?

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We have no real ground in the metro area, so lets build artificial reefs

What about the three mile reef, which extends pretty much up the whole northern metro coast? Out from Freo you've got Stragglers, Mewstones etc, with plenty of ground out there. In my opinion we've got plenty of reef.

Building artificial reefs is also bloody expensive. It cost Recfishwest around $2.4 mil to deploy the two artificial reef systems in Geographe Bay last year. If you're proposing to use offshore artificial reefs to draw the sharks away from the beaches, then I'm guessing you'd want artificial reefs along the whole metro coast? This would cost tens of millions of dollars.

I'm not sure if you realise, but restocking fish in an area isn't as easy as breeding up some fish and releasing them. Yellowtail kingfish for example, are a migratory species which often travel hundreds of km. Tagging studies on the east coast of Australia found that individuals move up and down the entire coastline, and even between Australia and New Zealand on occasion. You could spends hundreds of thousands breeding them and release them to your million dollar artificial reefs, just to have them leave within a matter of days. There's also the potential effects that releasing populations of fish could have on other fish populations within the region. They may decimate populations of smaller species, or conversely they may all be predated on by larger species.

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sloberchops said..

Drum lines are a work around that's not going to work over time, we need to deal with the root cause (yes it nerds ITIL). The root cause to big sharks coming in and eating people are there isn't enough food out deep for them. Let's fix the root cause and build artificial reefs for fish to live in. We have no real ground in the metro area, so lets build artificial reefs and not let anyone fish them for 5 - 10 years. Even replenish the reef with fish like kingfish, CSS is having a great new record in breading fish (kingfish). Let's build homes for fish and replenish the fish stock. If the sharks have food out there, then they don't need to come in and eat us. The drum lines will do one thing which as a temporary measure, which will reduce the big fish, which will reduce the competition for food. But if we don't deal with the root cause and we keep over fishing, this problem is only going to get worse. I started kiting last year because I can kite when it's too windy to fish and there isn't the fish out there of 10 years ago. We over use all of our natural resources.
If we really want to be real let's force the government to spend the cash now, build the habitat and populate it. Stop anyone fishing them and the fish will over populate these reefs and move to the natural reefs, it's a win win for everyone

what drugs are you on offyachops ?

Spot on Daniel_y.
Sloberchops, if there's a lack of food out deep, and we somehow waste millions on attracting more fish to an artificial reef in the metro area, then we will only attract more sharks as well. More sharks in Metro area is what we are trying to avoid. . . .
Also, big whitey bitey sharkies like big fatty mammals.White Sharks, the main cause of our fatal attacks have a thick blubber layer, similar to a whale. To keep this blubber layer up, the white sharkies prefer seals and humpback whale calves, which are full of fat, not nice lean meat from a kingfish. So, perhaps we need more seal breeding colonies and whales??? Doh - that's right - we've got lots of seals and whales around here - and therfore have lots of sharks too!

Sharks are opportunist feeders, see something that looks like food, bite it, human, spit it out, accidental, they are not hunting us.
If they were hungry there would be hundreds of attacks every year as there are hundreds of sharks out there and we would be like bait paddling around in nice clear water waiting to be eaten. This is not the case.

Migratory whale numbers, they have increased. Sharks follow whales and eat their babies/sick ones, hence why most of the sharks have gone now, cos so have the whales gone. Drum lines are catching nothing, they have been put in place to late to catch passing sharks. Hence we will have this pointless debate next year from nov-jan when the whales and sharks come back. IMO

sharks havent gone. Heard of a massive shark at woodies yesterday. Dorsal fin was as big as this blokes shin.

I can?t believe how little you guys know, what?s happening in our own waters. We have a yearly fishing ban on demersal fish for 3 months of the year, because we have fished the stock out so low. We have now stopped hunting Great whites so their numbers are growing.
The world?s oceans have been getting pillaged for decades with trawlers taking whole school of fish. At some stage, we have to start helping the fish population. Putting artificial reefs in water 20 to 40 meters deep, 10 + kms out (keeps them right away from beaches). Talk to the fisho, all the best fishing grounds out deep are are old sunken wrecks (manmade accidents).
We are going to spend what $1 million this year on shark drums x that by the next 10 years, that?s $10 million for 10 years. Spend $10 mill on artificial reefs and they are there for life. Tourists go down south to dive the reefs, they?ll do the same here. The state makes money. Provides a home and an ecosystem for the fish to live and breed. Builds something for our grand kids and their kids (think to the future not today).
The Korean and Japs have been building these for years, have you ever heard of any of them being bitten. No, because there is food for their big fish (or they have already eaten them). They don?t look after the world?s oceans but they do look after their own waters.
Information on reefs and there benefits before you write them off: http://www.fish.wa.gov.au/Fishing-and-Aquaculture/Recreational-Fishing/Pages/Artificial-Reefs.aspx
Pointing out about restocking was providing ideas, what we have done so far, which is nothing isn?t working. That?s why we now have drum lines. I want to know that when my mates and I go for a ride everyone is going to come back.

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sloberchops said..

I can?t believe how little you guys know, what?s happening in our own waters. We have a yearly fishing ban on demersal fish for 3 months of the year, because we have fished the stock out so low.

I'll just stop you right there. The demersal ban is 2 months a year, i.e. October 15 to December 15. That shows just how little you know.

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sloberchops said..

Tourists go down south to dive the reefs, they?ll do the same here. The state makes money. Provides a home and an ecosystem for the fish to live and breed. Builds something for our grand kids and their kids (think to the future not today).

So, you claim that putting these reefs in will attract large great white sharks, and hence draw them away from the beaches, yet you expect tourists to go out and dive the reefs? What kind of logic is that.

The artificial reefs down south obviously don't attract that many great whites, or the tourists (who are often the most afraid of sharks) wouldn't dive them.

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sloberchops said..
The Korean and Japs have been building these for years, have you ever heard of any of them being bitten. No, because there is food for their big fish (or they have already eaten them). They don?t look after the world?s oceans but they do look after their own waters.

I think you'll find that fish stocks (and the overall marine environment) here in WA are a hell of a lot better than in south east Asia. The vast majority of their predatory fishes have been depleted, which is indicative of poor ecosystem health, not 'well looked after' waters.

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sloberchops said..

Information on reefs and there benefits before you write them off: http://www.fish.wa.gov.au/Fishing-and-Aquaculture/Recreational-Fishing/Pages/Artificial-Reefs.aspx

There's actually no evidence that the artificial reefs deployed in Geographe Bay will enhance fish stocks. In many cases artificial reefs act as fish aggregation devices (FADs), drawing in and concentrating fish around a reef, however, do not actually enhance fish stocks. Given that the location of these reefs is publicly available, this has the potential to lead to the overfishing of certain species.

It will be many years before we actually know if the Geographe Reefs are actually enhancing fish populations, or simply acting as FADs.

Not another shark thread.

GWS prefer seals and whales.

So what's the answer, do we just do nothing and hope the problem goes away. Surely more fish in the sea will do something to help.

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sloberchops said..

So what's the answer, do we just do nothing and hope the problem goes away. Surely more fish in the sea will do something to help.

Yep pretty much. In my opinion we don't have a problem.

If the government really wanted to do something to keep people 'safe', I believe that investing more time into acoustic tracking of large sharks is a better alternative than trying to kill them. A few years ago there was a large focus on tagging animals, but it seems that now they have just decided culling is the best method to please the public. Fisheries have already deployed an array of acoustic receivers along the entire metro coast, each of which can detect acoustic tags within a diameter of approximately 1600m. By deploying these receivers in a grid, it is possible to track the position of tagged animals to within a few meters or less.

My solution would be to spend more effort on tagging sharks, and set up warning systems at beaches. These can either be manned or unnamed. If a large shark, which 'poses a risk to human life' is detected by the acoustic receiver, then it can set some sort of alarm off at that beach, and people who are afraid do not have to enter the water. This certainly won't guarantee that people will be safe, but neither do the drum lines. At least the government can say they are doing something, and people will be less afraid to go to the beach for a swim. The knowledge gained by acoustic tracking can also provide vital insight into the movment patters of the shakrs and better help us understand their home ranges, feeding habits, breeding habits etc.

Sloberchops - you're bringing up two different issues and confusing them.
Yes, I acknowledge all your points about global overfishing, SE Asia fishing vs Australian fishing practicies, current 2 month demersal fish ban in WA due to a combination of commercial and recrational overfishing etc.
However, the overfishing of the oceans is most likley not the root cause of the sudden spike in great whites along the SW WA coastline.
Whites, as per my previous post, are attracted to their key food source, seals and whales - espeically sick / young / injured etc. That's why lots of the shark attacks have occured in Spring, during the south-bound humpback whale migration, when lactating mothers and plump young calves are heading past the Perth and the SW.
I fully support sanctuary zones and other concepts, including appropriately placed artifical reefs to generate fish habitats. However, these efforts won't do bugger-all in regards to the shark issue, cause "FISH ARE FRIENDS, NOT FOOD" if you're a 5m great white!

I agree with you Danno. I've been postulating for some years that the big shark population increase is directly linked to the humpback whale herd size increase. I think there is some emerging science to support this as well.

My other theory is that the breaching/ water slapping behaviours we love to watch is a skill being taught to the young to (at least in part) frighten off a large predators.

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daniel_y said..

sloberchops said..

So what's the answer, do we just do nothing and hope the problem goes away. Surely more fish in the sea will do something to help.

Yep pretty much. In my opinion we don't have a problem.

If the government really wanted to do something to keep people 'safe', I believe that investing more time into acoustic tracking of large sharks is a better alternative than trying to kill them. A few years ago there was a large focus on tagging animals, but it seems that now they have just decided culling is the best method to please the public. Fisheries have already deployed an array of acoustic receivers along the entire metro coast, each of which can detect acoustic tags within a diameter of approximately 1600m. By deploying these receivers in a grid, it is possible to track the position of tagged animals to within a few meters or less.

My solution would be to spend more effort on tagging sharks, and set up warning systems at beaches. These can either be manned or unnamed. If a large shark, which 'poses a risk to human life' is detected by the acoustic receiver, then it can set some sort of alarm off at that beach, and people who are afraid do not have to enter the water. This certainly won't guarantee that people will be safe, but neither do the drum lines. At least the government can say they are doing something, and people will be less afraid to go to the beach for a swim. The knowledge gained by acoustic tracking can also provide vital insight into the movment patters of the shakrs and better help us understand their home ranges, feeding habits, breeding habits etc.

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Dave Whettingsteel said..

I agree with you Danno. I've been postulating for some years that the big shark population increase is directly linked to the humpback whale herd size increase. I think there is some emerging science to support this as well.

My other theory is that the breaching/ water slapping behaviours we love to watch is a skill being taught to the young to (at least in part) frighten off a large predators.

Well said.

To the comment on the sharks haven't gone, thats right, there seems to be suedo resident's, but the population of whites seems to increase around whale migration and decreases when the whales go. I have no evidence for this just my opinion. Does anyone know if this is true ? a bit sick of looking stuff up on sharks etc because it all points to what the gov. is doing is a waste of time.

I'm an Enviro scientist, who's studies the humpback whale migration on the NW shelf and Kimberly breeding areas.
Although not doing the research directly anymore, my fiance works with the murdoch cetacean research unit.
Current humpback whale Stock IV (WA coast population) number estimates are reaching pre-whaling estimates.
Recent findings of murdoch cetacean research unit is a significant increase in Killer Whale numbers around Exmouth and off Perth as well. It's not a long bow to draw to suggest that increased Killer Whale numbers are following the humpback migration, other top order predator populations such as great whites are also increasing in parallel.
Also, increased seal colony numbers, such as the NZ Fur Seal population of Rottnest are adding to the food supply.
The new fisheries research acoustic pinger buoy numbers are up aroudn 130 along the SW coast.
Another 2 years of the acoustic pinger research on the great whites will show if there is a correlation between humpback migration and great white numbers around the SW coastline.

Nice work if you can get it Danno!

Interesting that Killer Whales are increasing in number too. Hope they dont start coming in close to the beach!

I remember, maybe 20 years or so ago a mob of Killer Whales got caught up inside shark bay and put a big dent in the dugong population. I was talking to the CALM ranger about it and he said it was both horrifying and awesome to watch.

Thanks danno