IT'S April 2011, summer is well and truly over and Betty, a juvenile great white, has just surfaced off the coast of New South Wales.

It is the first time the female ocean predator has come to the top of the ocean in several hours and the only break she has had in several days.

For almost a month this young but big 'fish' has been making her way from the cool waters of the Bass Strait, some 800 kilometres behind her, to the warmer northern climes in search of food.

And boy is she hungry.

Luckily for Betty just a few kilometres ahead is Port Stephens where a smorgasbord of fish, rays and other sharks await her.

Betty spends the next few months dining out on this selection of marine life that frequent this stretch of coastline - one of only two known white shark nursery areas on the east coast - before she heads south.

For the next two weeks she hugs the coastline resurfacing every two to three days before arriving off the top end of the Victorian coast.

Her satellite tracking device, which was fitted at Christmas 2010, keeps transmitting her position every time she resurfaces from the ocean but then goes dead at the end of July 2011 recording 2400km in total.

It's another five months, at Christmas again, before Betty's tag begins transmitting once more.

Betty, still a juvenile and likely to be measuring at least 3.1 metres, pops up near Corner Inlet off the Victorian coast at the southern end of 90 mile beach - the other known white shark nursery area.

She spends at least a week in this popular feeding ground before beginning another journey.

But rather than head back down to the coastal waters of Tasmania as she did the previous year, Betty changes tack and begins a mammoth trek to the Great Barrier Reef.

And unlike the year before, Betty doesn't stop in any one place for great periods of time.

She basically swims continuously over the course of this journey along the coastlines of Victoria, NSW and Queensland, resurfacing multiple times along NSW but then submerging for days at a time until she reaches - what can only be assumed - was her intended destination, an area south of Swains Reef.

This pristine body of water 250km off the Queensland coast is rich with manta rays, sea snakes as well as recreational fishing-sized tuna, coral trout and giant trevally making it very popular with sharks.

By the time she makes her way back to the Victorian coastline she would have travelled a staggering 4500km in six months.

Details of this intriguing two-year journey covering almost 7000km and released for the first time to The Sunday Times, were collected by a satellite tracking tag as part of the CSIRO's shark tagging program.

Information collected over the course of the almost two-decade long project has led scientists to believe, that Betty will make this trek numerous times in her long life. But whether it will be the exact same journey, how long she will stay or why is still a mystery.

Australian scientists know white sharks follow food.

They know they can spend days, weeks, sometimes months in one area.

But predicting exactly when or how long they will stay - or what danger they pose to humans is still unknown.

As arguably Australia's top shark expert Barry Bruce knows more than most about these feared but fascinating creatures.

The CSIRO scientist and his team has scoured our oceans in search of answers for nearly 20 years.

The team have uncovered a treasure trove of riveting behavioural patterns that hopefully will help us - and government policy makers - to understand these ocean predators.

We now know, thanks to this research and that of collaborators at the University of Queensland, that Australia has two distinct populations of white sharks, one which travels up and down the east coast and sometimes across to New Zealand, and another which travels from South Australia all the way up the West Australian coast.

Generally these two populations do not venture past their side of the Bass Strait.

This is supported by the data collected by one of the more well-known satellite-tagged white sharks, Columba, a 3.5m 10-year-old female, who was tagged in 2006.

Columba travelled an estimated 3600km from the Neptune Islands, off South Australia, and the site of Australia's largest seal colony, up to Exmouth in WA's north and back again in less than six months.

After being tagged, Columba, whose journey is revered among CSIRO scientists, swam west then travelled through the shelf waters across the Great Australian Bight to Cape Leeuwin, before turning north.

Data collected from her track shows she then travelled in waters of 500-1000m in depth, for much of her trip to Exmouth. She then remained some 100km off Exmouth until early October that year before returning to The Bight. Her tag stopped transmitting in November 2006.

Yet, Bruce says, there is still so much we don't know and believes further research is key to finding out more.

His team's most recent project - studying juvenile white sharks off the NSW coast - led to the discovery that young white sharks congregate off the coast of Port Stephens, about 200km north of Sydney, for several months of the year before heading to the Corner Inlet/Lakes Entrance area in Victoria.

His team use both satellite and acoustic tags and collaborates with scientists in SA, WA and New Zealand.

So far, scientists have tagged more than 50 white sharks with satellite tags and almost 300 with acoustic tags throughout Australia.

Initially satellite tags gave scientists their first real glimpse of how far and fast sharks can travel in a day.

Bruce estimates a shark travels between three to five kilometres per hour and is capable of covering around 70 to 125km per day, 500-875 per week and 2200- 3150 per month.

But satellite tags are expensive, have a very short battery life and rely on the shark to surface before a position can be recorded. Researchers have now switched to using acoustic tags because they can last up to ten years and use receivers, which are deployed along our coastlines and are capable of recording much more data to collect the information. But collating and interpreting it takes more time.

In WA, shark scientists attached to WA Fisheries are in the midst of collecting and collating their first batch of data which researchers hope will give them a greater understanding of shark movements in WA.

Unlike in the east, there are no known nursery areas or big feeding precincts like the Neptune Islands along the WA coast.

The WA Government, which was this week forced to provide a very worried public with some sort of plan of action following yet another fatal shark attack, is hoping this data will also provide them with some answers.

And while some research has been able to give scientists, such as Bruce, some insight into great whites' behaviour, what it hasn't been able to do - and what the public want more than anything to know - is explain why a white shark attacks, and how to stop them.

But Bruce says no amount of research will ever completely tell us that.

"I would love our research to completely eliminate the risk of a shark attack but no amount of research, tagging or monitoring will ever do that," he said. "There are no simple answers other than a shark attack will always be a real but unlikely danger of entering the sea when we have healthy marine ecosystems of which Australia is blessed with.

"There are many theories why sharks occasionally bite people - but they are just that - theories. "There are good summaries of when, where and what shark species have been involved in attacks but these do not answer 'why'.

"Shark attacks are often quite different. Sometimes sharks act very aggressively towards people, but do not attack; sometimes people are not injured but their surf board or surf ski is damaged; some people suffer relatively minor injuries (even if a large shark is involved), some have one bite some more than one bite. Sometimes, the victim is not found and may have been completely eaten. That sharks attacks vary so much suggests that there are different reasons that lead to different styles of attack. We don't know why but such varied behaviour is common in many predators on land and in the sea. Shark attack, like any other form of accidental death or injury, is a terrible tragedy for all involved be it the victim, their family and friends or just people who witness or attend such incidents.

"One thing that is becoming clearer is that people and sharks (including white sharks) share the same space more frequently than we previously realised. This is not because numbers of sharks have suddenly increased; it is because we are getting better information on shark movements.

"The more we look the more we see. For example we know of some areas in eastern Australia where white sharks and people commonly swim at the same beach at the same time - yet there has never been an attack at these beaches - in fact in most cases you would not know they were there. The presence of white sharks is a poor indicator of attack risk and because of this there is no relationship between the number of sharks present in an area and the number of attacks (unless both are zero). This is because most encounters between white sharks and people lead to nothing - shark attack appears to be the exception rather than the rule. This is why interpreting a shark attack is so hard - there are no consistent patterns."

Over the past three years, six people have died in WA waters from a shark attack.

The latest, last weekend, claimed the life of Chris Boyd, a father-of-two who had been surfing off the coast of Gracetown in WA's south west.

It's the third fatal shark attack in that area in a decade prompting calls from those in the local community for a shark cull.

This week the state government, following mounting public pressure, said it would consider reviewing its shark policies but stopped short of saying it would look at culling.

However culling white sharks - a protected species - is a federal matter.

WA Fisheries officers can order that a shark which poses a threat to be captured then killed. But to this day not one has been destroyed. In fact Fisheries have never caught any shark that has been responsible for a fatal attack.

Bruce does not like to comment on government policies preferring to leave that to the politicians.

He sees his role, as do most shark scientists, as that of an adviser to provide information based on research.

But he also knows the decisions made will most likely take more into account than just scientific advice.

The WA government issued a catch and kill order in January this year after repeated sightings of a great white along Dunsborough beaches.

Bruce recognises there is a need to address public concerns.

But he does pose another question. Will trying to catch the shark result in the most effective use of resources?

"There are no guarantees that a shark sighted or caught after a shark attack will be the same shark involved," he said. "In general, attempts to capture 'the shark' involved after an attack has proved unsuccessful in all areas of the world where this has been attempted. A white shark may be over 100km away by 24 hours after an attack and there may be more than one shark moving through or present in the area. Resources put into attempting to catch a shark after an attack can be significant - but with little success."

But one area Bruce does voice his opinion is on other shark tagging programs, and in particular OCEARCH, the US based group which wants to come to WA to tag our sharks.

The CSIRO coordinates a national project on white sharks and is funded under the Federal Government-funded National Environmental Research Program (NERP).

It provides and shares data with the states on their projects to help give a national perspective.

The program has been running since the 1990s and uses satellite and acoustic tags to track great whites. OCEARCH wants to come to Australia to do the same but uses a different method to tag.

The group raises a shark out of the water and places it on a platform. The CSIRO and WA Fisheries do not.

Bruce seems insulted OCEARCH has implied the type of research they are proclaiming to do is different or more advanced that what has been and is happening in our waters.

Recently OCEARCH sent a proposal to the WA Government offering the use of its vessel and Bruce fears this latest tragedy will fuel their push to come to WA.

"No one tagging technology provides all of the data we need to understand white shark populations and I think it is important to note that Australian researchers have been using all of the technologies reported by OCEARCH for well over a decade - they are not suggesting anything new, "he said.

"I think it is fair to say that the system that WA Fisheries have in place is the most advanced anywhere in the world for monitoring acoustically tagged sharks.

"Naturally no system can tell you where untagged sharks are. Our job continues to be to provide the most robust information we can, to replace belief and speculation with scientifically defensible information and advice.

"How that information is used comes down to social and political decisions - the best we can do is to provide, over time, enough information for those making decisions - whether the general public or policy makers - to do so in the most informed way."

*Betty is a name The Sunday Times has given to the shark for the purpose of this story. The CSIRO stopped naming sharks after Columba*