Nth NSW sharks. Can they p!ss off already?

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Re: Nth NSW sharks. Can they p!ss off already?

Post by Cranked » Thu Sep 10, 2020 8:32 am

As I understand it, juvenile great whites prey on anything they can find. As adults they need high fat prey such as seals and whales, humans are way too boney with fcuk all fat.

We have protected their favorite food sources for decades now and completely stopped their main preditor (humans), so, just like crocs, their numbers are exploding.
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Re: Nth NSW sharks. Can they p!ss off already?

Post by swvic » Thu Sep 10, 2020 11:38 am

Question for steve and/or ‘boo;

I haven’t kept much notice of this, but are the apparent large number of sub adult/juvenile whites from a couple of very successful year classes? Anybody doing any research on this?

I know growth rates vary, but year/size data should be able to inform as to whether we can continue to expect continuation of increased numbers. The current chompers are getting close to breeding age. If the success continues, the numbers are going to increase pretty quickly. Scary thought
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Re: Nth NSW sharks. Can they p!ss off already?

Post by steve shearer » Thu Sep 10, 2020 11:42 am

good question Vic.

I'll try and find out.
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Re: Nth NSW sharks. Can they p!ss off already?

Post by Nick Carroll » Thu Sep 10, 2020 11:55 am

here's the CSIRO summary from 2018 on DNA research into white shark populations:

Looking for brothers and sisters among juvenile white sharks has provided the final pieces of information needed to estimate the size of populations in Australian waters.
Australia has two white shark populations, an eastern population ranging east of Wilson’s Promontory, Victoria, to central Queensland and across to New Zealand, and a southern-western population ranging west of Wilson’s Promontory to north-western Western Australia.
CSIRO-led research funded by the Marine Biodiversity Hub indicates there are approximately 750 adults in the eastern Australasian white shark population (with a range from 470 to 1030), and about double that number in the southern-western population.
The research also reveals the total number of white sharks in the eastern population is 5460, with a potential range between 2909 and 12,802. The total population could not be calculated for the southern-western population.
Details of the research methods and sampling, in the context of the eastern Australasian white shark population, are published today in the journal Scientific Reports. A report detailing further research and providing the latest population estimates has also been published today by the Marine Biodiversity Hub.
The research has also provided important details on adult survival rates, which were very high in the eastern population, in the range of 90 percent and above. This means that for 100 sharks alive this year, 90 would be expected to be alive next year.
For the southern-western population, the 2017 estimate is 1460 adult white sharks with a range of 760 to 2250. The adult survival rate is also estimated at above 90 percent.
The abundance estimates have been made possible thanks to decades of teamwork by CSIRO and research agencies in New South Wales, South Australia, Western Australia, Victoria and New Zealand.
Electronic tagging to track movements and survival, and biological studies to measure growth and breeding rates provided much of the information needed to model white shark numbers.
For example, juveniles fitted with internal acoustic tags by CSIRO and New South Wales Department of Primary Industries off NSW are tracked by a network acoustic receivers positioned along Australia’s eastern coast.
This network, coordinated by Australia’s Integrated Marine Observing System, monitors the juvenile sharks’ annual migrations, and how many survive from year to year.

Parental numbers found in the DNA of juveniles
Until now, information about adult white sharks has been elusive, because adults are very difficult to sample, particularly on the east coast. Thanks to a breakthrough in genetic and statistical methods, this problem has now been solved.
The breakthrough means scientists have been able to estimate adult shark numbers without having to catch or even see any adult white sharks. Instead, they located the tell-tale marks of the parents in the DNA collected from juveniles.
For the eastern population, researchers analysed DNA from 214 juveniles to find the genetic ‘marks’ of both parents. More than 70 individuals were found to share a parent, and this number has a statistical relationship to the total size of the adult population.
“The chances of any two juveniles in a population sharing a parent depends on how many adults are around to share the job of reproduction,” lead author of the paper, Dr Richard Hillary of CSIRO says.
“In a small population, more juveniles share a parent than in a large population, and vice versa.
“And as more juveniles are sampled over time, the parental marks we detect also reveal patterns of adult survival, which we determined to be greater than 90 percent in the east.
“We found many cases of parents (both male and female) that apparently had survived 20 or more years between the births of their children.”
Dr Hillary says population estimates for marine species generally require long-term datasets from sources such as fisheries catch records, but these don’t exist for white sharks.
“Other estimates have focussed on annual returns of sharks to particular sites, and extrapolated the results across entire regions, but there are challenges in these approaches that undermine their accuracy,” he says.
In the southern-western population, DNA samples were collected from 175 sub-adult and young adult males from Geraldton in WA to western Victoria. From these 175 samples, 27 were found to be half-sibling pairs (shared one parent).
The samples came from a variety of sources including necropsies of accidentally killed sharks, recovery of DNA from degraded tissues such as preserved jaws, and dedicated scientific sampling trips by CSIRO, the South Australia Research and Development Institute, Flinders University, and the Western Australian Department of Primary Industries and Regional Development (Fisheries).
A total population estimate has not yet been compiled for the southern-western population because direct estimates of juvenile survival rates (a crucial piece of information obtained by tagging a relatively high number of juvenile sharks) are not available.

Adult populations have been stable since protection
Adult populations for both the eastern and southern-western populations were estimated to have been stable since the onset of white shark protection (at the end of the 1990s).
This is consistent with the long time it would take for the effects of the various control programs and levels of fishing that existed pre-protection (which focused mostly on juveniles) to flow through to the adult population.
Sharks take 12–15 years to become mature adults, so we wouldn’t expect to see the effect on the adult population of that reduction in juvenile shark mortality until the next few years.
Estimating the trend in total population size for both populations requires continued teamwork, sampling and analyses, using methods and institutional relationships developed in this project.
“Now that we have a starting point, we can repeat the exercise over time and build a total population trend, to see whether the numbers are going up or down,” Dr Hillary said.
“This is crucial to developing effective policy outcomes that balance the sometimes conflicting aims of conservation initiatives and human-shark interaction risk management.”
This work was undertaken for the National Environmental Science Program Marine Biodiversity Hub, an Australian Government initiative to provide information and understanding to support biodiversity management and conservation in the marine environment, with support from collaborators in New South Wales, Western Australia, and South Australia.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by alakaboo » Thu Sep 10, 2020 12:23 pm

There's very little age-growth data for great whites (hard to get a good sample size when your test species is subject to CITES restrictions).

And what does exist is difficult to interpret, because they don't seem to lay down age rings in their vertebrae/otoliths/teeth in the normal annual pattern.

Just a few years ago some scientists recalibrated using C14 dating and dramatically increased the upper age limit (from 40ish to 70+ years). They also estimated female maturity at 33 years, 26 for males.
http://www.thedorsalfin.com/shark-news- ... re-slowly/
The findings are still fairly heavily disputed. The Australian government still estimate they mature at 7-10 years.

I suspect, like most fish, maturity and fecundity is based on health/weight. So if there is lots of food (salmon, whale calves) they mature younger and have more pups. They can have up to 10 per litter.

I've dissected jaws of a female GWS that was 4.6m long, it was somewhere between 14-17 years old. But that was probably done using the old methods, maybe it was early 20s?

It's been 21 years since they were first protected, so there's going to be another cohort of young along soon. Just unclear whether it's the 1st or 2nd generation since protection.

Edit: hadn't seen the genetic data Nick posted but it's broadly consistent with what I wrote.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by bomboraa » Thu Sep 10, 2020 6:43 pm

Nick Carroll wrote:
Wed Sep 09, 2020 6:15 pm
bomboraa it's a point but there's a lot of salmon out there. No lack of 'em offshore here that's for sure. The ocean's been more alive than ever.

A hunch, there's more sub adult white sharks around now than there has been for decades. Protection began in the mid 1990s. These animals are 17-20 years old. Prior to that there'd been a lot of thinning out of big female white sharks by fishos keen to see their jaws for a goodly sum on the black market to macho retards who wanted a pool room trophy. There's a species bounce back beginning and it's starting with a new generation of fuschia Millennial white sharks.
Hmmm Nick it may look like a lot of life around Sydney, but the salmon schools here and north have been noticably reduced. A few years ago schools would boil water across a football field size. They are now much smaller and scattered schools, which can still catch your eye because of the scavenging gulls but no denying a significant reduction in this smaller great white tucker. Big drop in bonito too, since they became the prime source of sushi rolls.
Too true about an increase in young sharks though.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by mario » Thu Sep 10, 2020 8:55 pm

If you`re south of Sydney around Bulli be careful tomorrow . My missus just bailed me up as I`m going for an early tomorrow .

https://www.illawarramercury.com.au/sto ... QIpjEO8mbI

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Re: Nth NSW sharks. Can they p!ss off already?

Post by crabmeat thompson » Fri Sep 11, 2020 7:12 am

pip maddison (@sharkgirlmaddison) makes a good point about shark mitigation.

we're still using technology and methods from the 1930's ... yet research and studies and what we know about shark behaviour has increased infinity from then.

the qld gov declaring two tiger's have been caught & destroyed (there was vision of them killing the big tiger onboard a boat with a bang stick) is pretty sickening & archaic politics and has nothing at all to do with Nick Slater's death.
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Re: Nth NSW sharks. Can they p!ss off already?

Post by swvic » Fri Sep 11, 2020 9:46 am

Thanks, nick and ‘boo

Really interesting, but not totally surprising that the east and southwest divide is at the southern tip of vicco. It’s shown to be consistent across many marine species. The general consensus is that during the last glacial period, Tasmania was part of the mainland and southern waters were too cold for many species to traverse so the populations became genetically distinct. Remixing those genes doesn’t happen quickly despite the biogeographic reconnection
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Re: Nth NSW sharks. Can they p!ss off already?

Post by The Mighty Sunbird » Fri Sep 11, 2020 10:27 am

KILL THEM ALL!
Erase.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by The Mighty Sunbird » Fri Sep 11, 2020 10:27 am

WITH BANGSTICKS!
Erase.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by The Mighty Sunbird » Fri Sep 11, 2020 10:28 am

UP THE CLACKER!
Erase.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by offshore1 » Fri Sep 11, 2020 10:35 am

Doctor Sunbird, I'd like to see your credentials please.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by steve shearer » Fri Sep 11, 2020 10:43 am

crabmeat thompson wrote:
Fri Sep 11, 2020 7:12 am
pip maddison (@sharkgirlmaddison) makes a good point about shark mitigation.

we're still using technology and methods from the 1930's ... yet research and studies and what we know about shark behaviour has increased infinity from then.

the qld gov declaring two tiger's have been caught & destroyed (there was vision of them killing the big tiger onboard a boat with a bang stick) is pretty sickening & archaic politics and has nothing at all to do with Nick Slater's death.
Yes and no.

I agree taking out those big tigers was totally unnecessary....they should have been tagged and released.

I also agree we are still using tech and methods from the 1930's apart from smart drumlins, which are totally modern tech.

Totally disagree that our knowledge of shark behaviour, and even basic shitt like their biology and spatio-temporal distribution has increased infinitely.

We still have no idea why they attack.

And Pip has been on the front-lines of the PR war trying to rehabilitate the sharks image. The backlash against Jaws.

Her quote: the true nature of sharks: timid, fearful of people, and really they just want to be left alone, quite clearly total BS when it comes to the species doing all the attacking, white sharks. Particularly juvey/sub-adults.

They are not timid or fearful. They are bold and curious, aggressive and very, very far away from wanting to be left alone.

Jaws may have gone too far but the modern shark conservationist view of sharks is as naive and anthropomorphic as Jaws was bloodthirsty.


Why can't we accept the fact that white sharks are an opportunistic, apex, ambush predator that likes to cruise the surf zone. More white sharks = more drive bys, encounters, circlings, bumpings, bitings and occasional full blown attacks like what we saw on poor old Nick Slater.
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Re: Nth NSW sharks. Can they p!ss off already?

Post by offshore1 » Fri Sep 11, 2020 10:44 am

Correct.

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Re: Nth NSW sharks. Can they p!ss off already?

Post by crabmeat thompson » Fri Sep 11, 2020 11:39 am

steve shearer wrote:
Fri Sep 11, 2020 10:43 am
crabmeat thompson wrote:
Fri Sep 11, 2020 7:12 am
pip maddison (@sharkgirlmaddison) makes a good point about shark mitigation.

we're still using technology and methods from the 1930's ... yet research and studies and what we know about shark behaviour has increased infinity from then.

the qld gov declaring two tiger's have been caught & destroyed (there was vision of them killing the big tiger onboard a boat with a bang stick) is pretty sickening & archaic politics and has nothing at all to do with Nick Slater's death.
Yes and no.

I agree taking out those big tigers was totally unnecessary....they should have been tagged and released.

I also agree we are still using tech and methods from the 1930's apart from smart drumlins, which are totally modern tech.

Totally disagree that our knowledge of shark behaviour, and even basic shitt like their biology and spatio-temporal distribution has increased infinitely.

We still have no idea why they attack.

And Pip has been on the front-lines of the PR war trying to rehabilitate the sharks image. The backlash against Jaws.

Her quote: the true nature of sharks: timid, fearful of people, and really they just want to be left alone, quite clearly total BS when it comes to the species doing all the attacking, white sharks. Particularly juvey/sub-adults.

They are not timid or fearful. They are bold and curious, aggressive and very, very far away from wanting to be left alone.

Jaws may have gone too far but the modern shark conservationist view of sharks is as naive and anthropomorphic as Jaws was bloodthirsty.


Why can't we accept the fact that white sharks are an opportunistic, apex, ambush predator that likes to cruise the surf zone. More white sharks = more drive bys, encounters, circlings, bumpings, bitings and occasional full blown attacks like what we saw on poor old Nick Slater.
lol ... you're so dramatic shep.

how do you know the sharks don't wanna be left alone? how do you know they don't prefer to be out deeper, away from shore hunting the prey they were designed to kill and eat? the same prey we remove by the thousands of tons each year to indulge with?

Nick slater wasn't "full blown attacked". there'd have been nothing left of him if he was -- he would have been consumed. the shark took a bite and let go. that's hardly all out aggression. as hard as it is to stomach, that is curiosity more than it is aggression.

just like a dog, it has no hands, all it's sensory devices are in its mouth and nose. when they explore something it's with their mouth too. whites (well, most sharks) have a devastating bite and cause catastrophic damage with their exploratory bite.

the irony is, it's impossible not to blame human interference with whatever is going on. fishing the oceans to within an inch of their lives, and protecting the apex end of the food chain. what did people think would happen?

i'd happily sacrifice seafood to leave the balance of the ocean alone. fuck, i'd do it even for a chance that leaving that balance alone could result in fewer attacks.
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Re: Nth NSW sharks. Can they p!ss off already?

Post by crabmeat thompson » Fri Sep 11, 2020 11:41 am

if humans were being eaten and no or little remains left behind ... then you're argument would hold weight. they are not. they're being bit once, and released straight away.
Kunji wrote:
Wed May 27, 2020 8:09 am
Would you mind throwing in a little more homoeroticism

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Re: Nth NSW sharks. Can they p!ss off already?

Post by steve shearer » Fri Sep 11, 2020 12:05 pm

Not dramatic.

Basic biology of the white shark: juveniles and sub-adults are coastal/inshore species. Their habitat is the surf zone. That's where they hunt, for teleost, elasmobranchs and cetaceans.
Thats the prey they were designed to hunt. Stingrays, dolphins, snapper, Aussie salmon etc etc.

They don't prefer to be out deeper, away from shore.

Inshore commercial fishing effort in NSW has declined by around 75%, marine parks and protected areas are now strung along the coastline. Licence buybacks are common. Australians import most of their seafood.
Here's an example. There used to be 36 trawlers operating out of Ballina. There are now 6.
Thats thirty less nets scraping and raping the inshore ocean every day.

The result is a major biomass rebound along the NSW coast. You only have to be in the water every day here to see that.

Predators need food and lots of it. Thats Biology 101.

The open ocean is being raped and the inshore coastal waters of NSW are thriving. Both those seemingly contradictory statements can be true.

There is abundant food to sustain juvenile/sub-adult white sharks in NSW, particularly NNSW. White sharks are a sign of a healthy ecosystem.

Thats is why they are here.

As for Nicks attack. Not sure if you saw the footage. From the size of and velocity of the rooster tail that was a full high speed hit from a large shark, no little bite and spit. There wasn't much left of his upper leg from the groin to the knee.

The white shark tends to bite then wait for exsanguination (bleed out) to avoid injury from large prey.

This is not a timid, shy animal.

Not being dramatic, we'll need to find ways to co-exist.

Trying to paint them as some shy, timid, misunderstood "Bambi of the deep" is not the way forward.

For some reason, we find it very hard to accept predators for what they are.

How do I know they don't want to be left alone?

From the sheer number of encounters and attacks in my region and other areas.
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