Reply With QuoteOh by the way the estimated that Crocodiles were going to kark their way off the planet too now look at the menaces up at Cardwell (on the news tonight )
Here is an abstract from :
Nicholas M. Otwaya , Corey J. A. Bradshawb,, Robert G. Harcourtc
a New South Wales Fisheries, Port Stephens Fisheries Centre, Private Bag 1, Nelson
Bay, NSW 2315, Australia
b Antarctic Wildlife Research Unit, School of Zoology, University of Tasmania,
Private Bag 05, Hobart, Tasmania 7001, Australia
c Marine Mammal Research Group, Graduate School of the Environment, Macquarie
University, Sydney, NSW 2109, Australia
Corresponding author. Tel.: +61 (0)3 6226 2644, Fax: +61 (0)3 6226 2745.
We estimated the time to quasi-extinction
(years elapsed for the population to consist of ˇÜ 50 females) for the grey nurse shark
population off the east coast of Australia based on current estimates of abundance and
known anthropogenic rates of mortality. We modelled time to quasi-extinction using
deterministic age- and stage-classified models for worst-, likely and best-case
scenarios.
Now guys these were their estimates .............
So now we better get out there and find a place absolutly infested with GNS and tell the dept they are full of it and prove the tree huggin hippies they are dead wrong because they obviously don't want to go looking any further than their noses for their sooky little sharks
Oh by the way the estimated that Crocodiles were going to kark their way off the planet too now look at the menaces up at Cardwell (on the news tonight )
A few quotes from here
http://www.deh.gov.au/media/dept-mr/cc02dec02.html
"The Grey Nurse Shark has been protected from fishing in NSW waters since 1984, however shark numbers are still on the decline," Valerie Taylor said.
"Recent diver surveys for NSW Fisheries recorded approximately 206 Grey Nurse Sharks impaled by fishing hooks. More than 90 percent of these hooks were identified as recreational hooks and less than 10 percent as commercial hooks," Ron said.
If this is the same Ron and Valerie Taylor I am thinking of, they used to pop grey nurse sharks with powerheads in the 60's or 70's. So they probably have a reasonable knowledge of what the GNS populations once were.
Online Dictionary = Science
The observation, identification, description, experimental investigation, and theoretical explanation of phenomena.
Such activities restricted to a class of natural phenomena.
Such activities applied to an object of inquiry or study.
Science is a best educated guess taking into consideration a combination of assumptions and as many facts as you have available to you, using fairly standard accepted methodoligy.
I don't know whether the closures were right or wrong, but with extinction its a once only shot, get it wrong and "oops sorry" really doesn't mean shit then.
There are plenty of crocs..that is because they are protected..a good example of how the numbers increase when the animals are protected.Originally Posted by mangrovejack7
Ok here are some facts not assumptions!!!!!
Habitat requirements:
The Grey Nurse Shark lives in shallow coastal waters from the surf zone down to 60m, although it has been recorded from water as deep as 190m.During the day, they are generally found in the vicinity of drop-offs, caves and ledges. Grey Nurse Sharks are found in tropical and temperate waters in the Atlantic, Indian and western Pacific Oceans.
Research conducted in NSW and Queensland waters has shown that fishing hooks are one of the main causes of death, as they become embedded in the sharks and can cause serious infection. Sharks can also starve, as the hooks may disrupt their feeding and digestion. Since 2002, visual surveys undertaken at Wolf Rock by QPWS and University of Queensland SCUBA divers have recorded several grey nurse sharks trailing various forms of fishing tackle. To date, during any single dive the maximum number of sharks sighted with fishing tackle trailing is 4 individuals (all mature females) out of a total of 16 sharks sighted during that dive.
Now as one knows divers are restricted to a limited depth. Well these sharks aren't!!!!! My point is that divers only see and record what they are able to see and if the viewing isn't up to their standards "they cry wolf "well apparently they must be too lazy or incompetent to venture out to actually find more GNS in depths that they can't possibly reach or don't look in other places because that might consume more fuel. Also I find that it is still legal for divers to use and carry power heads if any sharks seem to be a threat. And how do they get their sharks for Autopsies the department seems to say that fish hooks are to blame for sharks karking it however I think in this situation more research is needed to make a better conclusion than the hooks being the real issue here.
In conclusion I feel that the recreational and departmental divers have a personal vendetta against fishermen and they have no business to make wild assumptions as to counting one area for sharks and treating it like they know what is in the 190 meter plus depths below the Atlantic, Indian and western Pacific Oceans.
I dont mind facts I just hate B.S.
Well, I'll be stuffed!! Still!! This thread seems to be about whether Flat Rock, etc should be reopened to trolling. Where is the evidence that TROLLING stuffs GNS? Or even the assumptions, theories, guesses or just plain gut feelings. My point is that if NSW Fisheries with their long term GNS studies allow trolling in the GNS closure areas, what does Qld Fisheries
know that is different? ???
>
And if anyone wants to bring up crocs breeding up 'cos they are protected, then that's OK too. But you have to remember that in a lot of places they are breeding on the banks of heavily used rivers & waterways often close to large towns. Don't believe me? then go for a swim off the boat ramp at Keith Williams development at Hinchinbrook. Or dive off one of the trawler wharfs in Smiths Creek in Cairns at night.
ROLL TIDE, ROLL.................
Regards,
Peter
To date, during any single dive the maximum number of sharks sighted with fishing tackle trailing is 4 individuals (all mature females) out of a total of 16 sharks sighted during that dive.
i believe this is very selective reporting ????
moon phase, time of day, winter, summer,,, does this have am affect on the number of sharks present at the time of these dives. ??? ???.
"whats the time"
"In conclusion I feel that the recreational and departmental divers have a personal vendetta against fishermen and they have no business to make wild assumptions as to counting one area for sharks and treating it like they know what is in the 190 meter plus depths below the Atlantic, Indian and western Pacific Oceans.
I dont mind facts I just hate B.S."
You appear to have no facts to support your claims and are making wild assumptions to suit your own requirements. That is fine..you have just put yourself in the category of those you are castigating ..full of B.S. but go ahead..fish the crap out of it all..who cares if all the sharks die..no one...just another cog taken out of the food chain...and as each cog disappears then you will find someone else to blame..the Pros..the scientists..maybe the Govt..who knows..but just keep on doing what you are doing and everything will be hunky dory...some people seem to think they have a right ot do what they want..when they want and stuff everyone else...gotta love it.
Pinhead in the paperwork I had sent to me from the dept had the words:
estimated=15times
estimates=24times
probability=11times
critically =4times
aproximately=6times
assuming =9times
endangered =9times
extinction =56times
Not once was the words written :
Proof
Definatly
certain
positively
for sure
fact
Let me sell you a car one day pinhead I'll make it look so good on paper you will just need to buy it Ha Ha Ha Ha
I totaly agree mangrovejack7 the number and survival of GNS can't be limlted to just this area. I also don't know a fisherman out there that wants to catch a GNS. Iam with you i like to go out on charters and mates boats for the day(weather permiting )and catch a few snapper for tea. I am positive that if the fish swim away from flat rock for a couple of days the sharks soon follow and will quite often travel great distances to feed on schools of bait etc.Pin head ever been to townsville? Cleveland bay is one of the biggest breeding grounds for GNS but ships still cruise it and fish it they like humans adapt and overcome so think outside the square unlike DPI. I am sure they are smart but have they ever tried to follow a shark i am sure it wont hang around a rock all it 's life waiting for a feed. >
Do a search on Google and see that every authority from the UN down has the GNS as endangered..but what would any of them know? You guys are obviously more learned than any of them...so who cares about the sharks...they are okay cos you guys said so. OR..is it because you just want your feed of fish and to hell if it matters that one species becomes extinict because of it.
Just have a read of this site: http://www.marine.csiro.au/research/tagging/greynurse/
I somehow think the CSIRO has a pretty good idea of what they are doing hence the ongoing research into the sharks and their aggregation sites.
"Proof
Definatly
certain
positively
for sure
fact"
Well jack, where is your definite proof to back up your argument..items that you are certain of and will positivley back them up against any scrutiny. Are you sure your facts are complete and not based on a couple of fishing trips.
I await eagerly your definitve proof that GNS are not endangered and that Flat Rock should be open for all and sundry and that any sharks that are killed there will have no effect on the population whatsoever.
I would expect detailed case studies..exact population counts...times and dates of these precise population counts..this will make good reading then we can issue your report to all the authorities so they can remove the GNS from the endangered list because you say that fishing at Flat Rock has no bearing on the sharks therefore fishing in any location will have no effect on the sharks at all.
See a few words here that should help Quasi: Merriam Webster,
1 : as if : as it were : in a manner : in some sense or degree : SEEMINGLY, ALMOST *the legatee was quasi an heir O.W.Holmes *1935* usually joined to second element with a hyphen *a quasi-historical narrative*
following post will show how a POPULATION MODELING APPLICATION is put together, and as you read it will understand it is mainly guess work, as it all involves chance and probablity. not really good science in my books, guess thats why i turned from statistics to social sciences.
cheers
Joe.
POPULATION MODELING APPLICATION:
POPULATION VIABILITY ANALYSIS (PVA)
For simplicity we define the following:
Population:
A group of individuals of the same species inhabitating a defined area at the same
time
Population viability:
The probability that population will survive for a specified amount of time (usually
100 years)
Population viability analysis:
The methodology for estimating the probability that a population will persist for a
pre-specified amount of time
Minimum viable population size:
Smallest population size that will allow a population to persist for some prespecified
time
PVA usually requires a simulation model, but see below
Remember: All models are wrong- and some are useful (see Box 1979), so these are not
estimates of “true” extinction probabilities.
Termed QUASI-extinction probabilities
Estimating quasi-extinction probabilities
Population dynamic models
Leslie Matrix (Age or Stage – based models)
Individual based models (IBM, see DeAngelis and Gross 1992)
What basic information do we need to model populations?
Reproduction – Ricker/ Life cycle
Survival -
Growth -
Immigration -
Emigration -
These processes are not deterministic, but stochastic
Definition of stochastic
Involving chance or probability: a stochastic stimulation.
Sources of variation potentially affecting population persistence and estimates of
quasi-extinction probabilities
Process Variation: Stochasticity in the population dynamic processes
Sampling Variation: Measurement error associated with sampling a population
Process variation:
Demographic stochasticity – represents variation about the expected number of
births and deaths
Class coin flipping exercise
Small populations are greatly affected by demographic stochasticity just like
flipping a single coin doesn’t guarantee a “head,” but flipping the coin 1000 times
probably will.
Temporal and spatial stochasticity – Vital rates are actually random variables.
They will vary through time (due to changes in weather, disease)
Increasing temporal variation decreases persistence (Stacy and Taper example)
Are years independent?
Are survival, birth, etc. rates independent?
Stacy and Taper showed that acorn woodpecker PVA estimates were significantly
affected by whether density dependence was included in the simulation model.
When it was, persistence increased.
Spatial variation in the landscape – immigration will lead to greater persistence
(Stacy and Taper example)
Individual variation- Differences among individuals. Increased individual
heterogeneity results in greater chance few animals have high rates coupled with
possible shift in traits (selection) will lead to higher persistence. (White example)
How can we estimate these?
Alternatives to population modeling
Diffusion Approximation Method (Dennis et al. 1991)
Requires a time series of population size or an index of population size
didn't post the rest as its all figures.
cheers
Joe
Crayman - not sure what you're on about GNS in Townsville??? Cleveland Bay may be home to other, smaller nurse sharks but NOT the Grey nurse shark, unless you mean the ones in the big aquarium?
I'm on your side pinhead - there are heaps of crocs because they were protected - simple. It's no good blaming others, the fact is there are relatively few breeding female GNS left. Even if the numbers are closer to 1000 than 100, 1000 individual animals is a very small number.
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