Farming carbon can be a win for wildlife, if the price is right

Koalas are one of the threatened species that could benefit from carbon farming. christopher charles/Flickr, CC BY-NC-SA

Koalas are one of the threatened species that could benefit from carbon farming. christopher charles/Flickr, CC BY-NC-SA

Megan Evans, Australian National University; Anna Renwick, The University of Queensland; Josie Carwardine, CSIRO, and Tara Martin, CSIRO

Climate change and the loss of biodiversity are two of the greatest environmental issues of our time. Is it possible to address both of those problems at once?

In Australia, farmers and landholders will this week be able to apply for payments through the Federal government’s A$2.55 billion Emissions Reduction Fund. Bidders can request funding for projects that reduce emissions using agreed methods, which include approaches relevant to the transport, waste and mining sectors, as well as the land sector: for example, by managing or restoring forests.

Forests hold carbon in vegetation and soils and provide important habitat for native wildlife. Restoring forests in areas where they have been cleared in the past could be good for the climate, good for biodiversity, and generate additional income for landholders.

How well the Emissions Reduction Fund can achieve these benefits will depend on three things: the right approach, the right price, and the right location.

Farming carbon

There are a range of approaches available for restoring forests, and they vary in how quickly carbon can be sequestered, cost, and suitability for wildlife.

For example, fast-growing monocultures such as blue gum plantations can sequester carbon very rapidly, but don’t provide ideal habitat for wildlife. Planting a diversity of native trees and shrubs using an approach called environmental plantings is far more wildlife-friendly, but the costs are higher, and carbon is not stored as quickly.

A third possible approach is to assist the natural regeneration of vegetation. This can be done by fencing off cattle or by ceasing on-farm practises such as burning or disturbance with machinery. Assisted natural regeneration is the cheapest of these three possible methods, and is also good for biodiversity: our recent paper found that it could be a great option for restoring forests in agricultural landscapes across Queensland and northern New South Wales.

Brigalow woodlands allowed to regrow for 3-10 years. Image: John Dwyer

Regenerated brigalow woodlands after 50 years. Image: John Dwyer

Location, location, location

Across Australia, there are a number of places where growing carbon could be a more profitable option than the current land use. Some of these places are more important for biodiversity than others.

The mulga lands of western Queensland may be worth more as carbon farms than other uses. Image: Don Butler

If we’re interested in getting some wins for biodiversity while growing carbon forests, we need to think carefully about the possible opportunities and trade-offs, as the best places for sequestering carbon are not always the most beneficial for biodiversity, and vice versa.

In our recent paper, we found that it is possible to identify where growing forests could provide win-wins for both carbon and biodiversity.

For example, the top 25% of priority areas for environmental plantings could sequester 132 million tonnes of CO2 equivalent annually, which is almost a quarter of Australia’s annual emissions (excluding those caused by land-use change).

Relative priority areas for restoring 139 threatened ecosystems to 30% of original extent using environmental plantings, where carbon is stored at $20/tonne. Pink areas are higher priority, green is lower priority http://bioscience.oxfordjournals.org/content/65/4/372

These high-priority areas for environmental plantings could restore some of the most threatened ecosystems in Australia. There are 139 ecosystem types across the country that have lost more than 70% of their original extent. If it were possible to restore these ecosystems up to 30% of their original extent, they will have a better chance of surviving in the long term.

Restoring parts of the landscape with these ecosystems is a high priority for biodiversity – not only are the ecosystems rare, but many of the birds and animals that depend on these ecosystems are those that are most threatened. For example the brigalow woodlands of south east Queensland, of which less than 10% remain, are home to nationally threatened koalas and a host of other wildlife.

The right price

It will generally be more expensive to grow carbon forests that also provide benefits for biodiversity. This is because the places most profitable for land uses such as agriculture are often where the most threatened species and ecosystems are located.

In our analysis, we found that with a price on carbon equivalent to A$5 per tonne, it would not be profitable to restore threatened ecosystems up to 30% of their original extent. This means that without additional funding from another source, there is limited opportunity to achieve wins for biodiversity if the price on carbon is low.

However, a higher price of A$20 per tonne, reflecting Australia’s 2011-2013 carbon price, could allow up to half of the heavily cleared vegetation types to be restored up to 30% without any additional funding for biodiversity itself. At this A$20 price, we also found that it made more economic sense to farm carbon than the existing land use, in over 1.2 million hectares in Queensland.

This week’s Emissions Reduction Fund auction will be a good first test of how the current approach to carbon farming can provide the dual benefit of restoring habitat for native wildlife and addressing climate change. Our analysis shows that Australia’s climate policies could have a very significant impact on biodiversity – if we think carefully about the right approach, price, and location.

The Conversation

This article was originally published on The Conversation.
Read the original article.


Australia’s Next Top climate models

Some of Melbourne’s climate analogues for 2090 under a high emission scenario

Some of Melbourne’s climate analogues for 2090 under a high emission scenario

By Chris Gerbing

We all have an interest in whether rain will dampen our day and a curiosity about what the skies hold for next week. We are all impacted when the weather turns extreme, sometimes in devastating ways. And we have a yearning to know what the future might hold for our climate, so that we can plan ahead.

Weather and climate may never be completely predictable, but science has come far enough for us to be breaking new ground when it comes to projecting what Australia’s climate may look like decades – or even hundreds of years – in the future.

And here’s a sneak peak into the future – by the year 2090, Sydney could have the climate of Brisbane, and Melbourne could have the climate of Dubbo.

Climate models help us to understand our present weather and climate, and also allow us to consider plausible future scenarios of how the climate might change. Climate models are built using mathematical representations of the dynamic Earth system. Their fundamentals are based on the laws of physics including conservation of mass, energy and momentum. They create simulations to tell us what happened or what might happen under a range of different scenarios (such as greenhouse gas concentrations).

Check out this animation about climate models.

Along with the Bureau of Meteorology, we’ve used as many as 40 climate models, produced by international global climate modelling groups, to create projections for Australia’s climate, all the way out to the year 2090. The projections consider up to 15 regions of Australia, a small set of plausible future greenhouse gas scenarios and four future time periods.

Climate change projections are presented as a range of possibilities. This occurs because different models produce different projections. Even though they are based on the same physical laws, such as conservation of mass, moisture and energy, each climate model treats regional processes in the oceans and atmosphere slightly differently. It is important to explore the full range of possibilities in any impact assessment.

Even if we significantly reduce our greenhouse gas emissions as under an intermediate scenario, Melbourne’s annual average climate could look more like that of Adelaide’s, and Adelaide’s climate could be more like that of Griffith in New South Wales.

Eastern Australian coastal sites could see a climate shift to those currently typical of locations hundreds of kilometres north along the coast. Sydney’s climate could resemble that of Port Macquarie, and Coffs Harbour’s climate resembling that of the Gold Coast (by 2050; intermediate emissions).

These analogues, and others for more than 400 towns, can be found using a climate analogues tool –  one of 13 tools that can be found on the Climate Change in Australia website.

This research received funding from the Department of Environment under the Regional Natural Resource Management Planning for Climate Change Fund. Additional funding was provided by CSIRO and the Bureau of Meteorology.

We have published two articles over on The Conversation which takes a deeper look into the details of these climate models and projections.


Here are five questions about tropical cyclones that you need answered

Tropical Cyclone Marcia swirls menacingly off the Queensland coast. Photo Credit: NASA

Tropical Cyclone Marcia swirls menacingly off the Queensland coast. Photo Credit: NASA

By Simon Torok

Tropical cyclones are an ongoing threat during Australia’s cyclone season, which generally lasts from November to April. On average, the Australian region experiences 13 cyclones a year.

But as the coastlines of Queensland and the Northern Territory are threatened on two simultaneous fronts (Marcia and Lam), we’ve asked our climate scientists what we can expect from tropical cyclones in the future, as Australia’s climate continues to change.

1. Has the frequency of tropical cyclones changed?

Some scientific studies suggest no change and others suggest a decrease in numbers since the 1970s in the frequency and intensity of tropical cyclones in the Australian region.

The Bureau of Meteorology’s satellite record is short and there have been changes in the historical methods of analysis. Combined with the high variability in tropical cyclone numbers, this means it is difficult to draw conclusions regarding changes.

However, it is clear that sea surface temperatures off the northern Australian coast have increased, part of a significant warming of the oceans that has been observed in the past 50 years due to increases in greenhouse gases. Warmer oceans tend to increase the amount of moisture that gets transported from the ocean to the atmosphere, and a warmer atmosphere can hold more moisture and so have greater potential for intense rainfall events.

A rare moment of light captured during the Cyclone Tracey salvage mission. Source: CSIRO archives

A rare moment of light captured during the Cyclone Tracy salvage mission. Source: CSIRO archives

2. Will the frequency of tropical cyclones change in future?

The underlying warming trend of oceans around the world, which is linked to human-induced climate change, will tend to increase the risk of extreme rainfall events in the short to medium term. Studies in the Australian region point to a potential long-term decrease in the number of tropical cyclones each year in future, on average.

On the other hand, there is a projected increase in their intensity. In other words, we may have fewer cyclones but the ones we do have will be stronger. So there would be a likely increase in the proportion of tropical cyclones in the more intense categories (category 4 or 5). However, confidence in tropical cyclone projections is low.

3. What are the impacts of tropical cyclones?

Today, coastal flooding is caused by storm tides, which occur when low-pressure weather systems, cyclones, or storm winds elevate sea levels to produce a storm surge, which combines with high or king tides to drive sea water onshore. Although rare, extreme flooding events can lead to large loss of life, as was the case in 1899 when 400 people died as a result of a cyclonic storm surge in Bathurst Bay, Queensland.

4. How will impacts of tropical cyclones change in future?

With an increase in cyclone intensity, there is likely to be an increased risk of coastal flooding, especially in low-lying areas exposed to cyclones and storm surges. For example, the area of Cairns’ risk of flooding, by a 1-in-100-year storm surge, is likely to more than double by the middle of this century.

5. How can we adapt to expected changes?

Almost all of our existing coastal buildings and infrastructure were constructed under planning rules that did not factor in the impacts of climate change. However, governments are now taking account of changes in climate and sea level through their planning policies. Just as the building codes and rules for Darwin changed in the wake of Cyclone Tracy, so they should now be re-assessed for each region and locality in Australia to take account of climate change.

You can track both Tropical Cyclone Marcia and Lam using our Emergency Response Intelligence Capability tool (ERIC).

ERIC - our emergency response tool displaying the paths of Tropical Cyclone Marcia and Lam across our north-eastern coastlines.

ERIC – our emergency response tool displaying the paths of Tropical Cyclone Marcia and Lam across our north-eastern coastlines.

And we also have more information about our latest climate projections here.


Eight million tonnes of plastic are going into the ocean each year

Plastic waste washed up on a beach in Haiti. Image: Timothy Townsend

Plastic waste washed up on a beach in Haiti. Image: Timothy Townsend

By Britta Denise Hardesty, CSIRO and Chris Wilcox, CSIRO

You might have heard the oceans are full of plastic, but how full exactly? Around 8 million metric tonnes go into the oceans each year, according to the first rigorous global estimate published in Science today.

That’s equivalent to 16 shopping bags full of plastic for every metre of coastline (excluding Antarctica). By 2025 we will be putting enough plastic in the ocean (on our most conservative estimates) to cover 5% of the earth’s entire surface in cling film each year.

Around a third of this likely comes from China, and 10% from Indonesia. In fact all but one of the top 20 worst offenders are developing nations, largely due to fast-growing economies but poor waste management systems.

However, people in the United States – coming in at number 20 and producing less than 1% of global waste – produce more than 2.5 kg of plastic waste each day, more than twice the amount of people in China.

While the news for us, our marine wildlife, seabirds, and fisheries is not good, the research paves the way to improve global waste management and reduce plastic in the waste stream.

Lindsay Robinson/University of Georgia

Follow the plastic

An international team of experts analysed 192 countries bordering the Atlantic, Pacific and Indian Oceans, and the Mediterranean and Black Seas. By examining the amount of waste produced per person per year in each country, the percentage of that waste that’s plastic, and the percentage of that plastic waste that is mismanaged, the team worked out the likely worst offenders for marine plastic waste.

In 2010, 270 million tonnes of plastic was produced around the world. This translated to 275 million tonnes of plastic waste; 99.5 million tonnes of which was produced by the two billion people living within 50 km of a coastline. Because some durable items such as refrigerators produced in the past are also thrown away, we can find more waste than plastic produced at times.

Of that, somewhere between 4.8 and 12.7 million tonnes found its way into the ocean. Given how light plastic is, this translates to an unimaginably large volume of debris.

While plastic can make its way into oceans from land-locked countries via rivers, these were excluded in the study, meaning the results are likely a conservative estimate.

With our planet still 85 years away from “peak waste” — and with plastic production skyrocketing around the world — the amount of plastic waste getting into the oceans is likely to increase by an order of magnitude within the next decade.

Our recent survey of the Australian coastline found three-quarters of coastal rubbish is plastic, averaging more than 6 pieces per meter of coastline. Offshore, we found densities from a few thousand pieces of plastic to more than 40,000 pieces per square kilometre in the waters around the continent.

Where is the plastic going?

While we now have a rough figure for the amount of plastic rubbish in the world’s oceans, we still know very little about where it all ends up (it isn’t all in the infamous “Pacific Garbage Patch”).

Between 6,350 and 245,000 metric tons of plastic waste is estimated to float on the ocean’s surface, which raises the all-important question: where does the rest of it end up?

Some, like the plastic microbeads found in many personal care products, ends up in the oceans and sediments where they can be ingested by bottom-dwelling creatures and filter-feeders.

It’s unclear where the rest of the material is. It might be deposited on coastal margins, or maybe it breaks down into fragments so small we can’t detect it, or maybe it is in the guts of marine wildlife.

Plastic recovered from a dead shearwater – a glowstick, industrial plastic pellets, and bits of balloon

Wherever it ends up, plastic has enormous potential for destruction. Ghost nets and fishing debris snag and drown turtles, seals, and other marine wildlife. In some cases, these interactions have big impacts.

For instance, we estimate that around 10,000 turtles have been trapped by derelict nets in Australia’s Gulf of Carpentaria region alone.

More than 690 marine species are known to interact with marine litter. Turtles mistake floating plastic for jellyfish, and globally around one-third of all turtles are estimated to have eaten plastic in some form. Likewise seabirds eat everything from plastic toys, nurdles and balloon shreds to foam, fishing floats and glow sticks.

While plastic is prized for its durability and inertness, it also acts as a chemical magnet for environmental pollutants such as metals, fertilisers, and persistent organic pollutants. These are adsorbed onto the plastic. When an animal eats the plastic “meal”, these chemicals make their way into their tissues and — in the case of commercial fish species — can make it onto our dinner plates.

Plastic waste is the scourge of our oceans; killing our wildlife, polluting our beaches, and threatening our food security. But there are solutions – some of which are simple, and some a bit more challenging.

Solutions

If the top five plastic-polluting countries – China, Indonesia, the Philippines, Vietnam and Sri Lanka – managed to achieve a 50% improvement in their waste management — for example by investing in waste management infrastructure, the total global amount of mismanaged waste would be reduced by around a quarter.

Higher-income countries have equal responsibility to reduce the amount of waste produced per person through measures such as plastic recycling and reuse, and by shifting some of the responsibility for plastic waste back onto the producers.

The simplest and most effective solution might be to make the plastic worth money. Deposits on beverage containers for instance, have proven effective at reducing waste lost into the environment – because the containers, plastic and otherwise, are worth money people don’t throw them away, or if they do others pick them up.

Extending this idea to a deposit on all plastics at the beginning of their lifecycle, as raw materials, would incentivize collection by formal waste managers where infrastructure is available, but also by consumers and entrepreneurs seeking income where it is not.

Before the plastic revolution, much of our waste was collected and burned. But the ubiquity, volume, and permanence of plastic waste demands better solutions.

The Conversation

This article was originally published on The Conversation.
Read the original article.


It’s raining water tanks: top tips for keeping them healthy and efficient

Rainwater tank

The humble rainwater tank sits silently, dutifully doing its part for the environment – and your wallet. Picture Credit: blog.savewater.com.au

Australia is the driest populated continent in the world, and yet our water consumption per person is among the highest on the planet. For Australians, water is scarce and how we manage this resource is a concern for us all.

It’s no surprise that people are looking to install some form of water catchment for their property. Recent data shows that 26 per cent of Australian homes have already installed a rainwater tank and an overwhelming majority reported that they are positive about the tanks.

From saving money on your water bills to the conservation of a valuable natural resource, there is a lot to like about the humble rainwater tank.

More than a quarter of Australian households have a rainwater tank. Picture credit: ABC.net.au

They can even have other positive flow-on effects for the community. For example, the use of rainwater tanks in urban areas can relieve pressure on public infrastructure because of reduced stormwater runoff. We’ve also seen the popularity of rainwater tanks increase year on year, with the ABS reporting that the total storage capacity in Australia has gone up by 30 per cent between 2006 and 2011.

This is all very encouraging news for the environment – but, it’s not all drinking water and skittles. Just like buying a puppy dog or a Tamagotchi, owning a rainwater tank comes with its own responsibilities.

A recent study we conducted with the Smart Water Fund has shown that households may not be aware of some of the maintenance requirements that come with rainwater tank ownership.

In the report, Survey of savings and conditions of rainwater tanks, we conducted extensive research into rainwater systems across Melbourne, looking at the efficiency of the tanks and the water savings that can be generated at an individual household level.

One of the most interesting findings was lack of awareness around maintenance. Only 58 per cent of Melbournians indicated that they have conducted some form of maintenance on their system.

It’s important to know that the installation of a rainwater tank isn’t a set-and-forget scenario. There are some maintenance tasks that are unavoidable if you want to keep the tank healthy and efficient.

So here are our top tips for rainwater tank owners, or those considering a purchase in the near future.

Top 5 tips for maintaining your rainwater tank

Gutter-talk doesn’t always need to be dirty, keeping your gutters clean throughout the year will have a noticeable effect on your water quality. Picture credit: Hand Man Avisar

  1. Get your mind (and the leaves) out of the gutter – every 3 months 
  • Cleaning out the gutters is a simple way to improve the water quality and the efficiency of the tank.
  • 4 per cent of tested households were found to have faecal matter in the gutters. In addition, 31 per cent of sites inspected were found to have half or completely full gutters.
  • Look into installing gutter meshing.

Nobody wants insect larvae in their water. A working mozzie mesh is an easy way to keep these pests out and your water clean.

Nobody wants insect larvae in their water. A functioning mozzie mesh is an easy way to keep these pests out and your water clean.

  1. Mozzie mesh – every 3 months
  • A rainwater tank is a great place for mosquitoes and pests to set up shop and thrive.
  • Of the tanks reviewed in the study 91.1 per cent had mosquito meshing, but more than 10 per cent were in a condition that would allow pests or vermin into the tank.
  • Poorly maintained mesh can pose a risk to the health of the community, particularly if populations of disease carrying insects are free to multiply in the rainwater tank hotel in your backyard.

Sendiment and Tannin water

Not exactly the kind of water you would like to shower with. This dark brown sample indicates high levels of sediment and tannins.

  1. Spend some quality time getting to know your water quality – every 6 months
  • A majority of households use rainwater for the toilet or the washing machine so cleanliness of the water is less important. However, for those properties that use the water for showers, drinking or cooking, checking the water is crucial.
  • We found 57 per cent of tanks had discoloured water and 19 per cent had odorous water, while 25 per cent of tanks had medium or high concentrations of sediment.

Broken Pipes

Losing water from a leaky pipe is a complete waste and runs counter the reason you installed the tank in the first place. Photo credit: savethewater.org

  1. Pump it real good – every 6 months
  • The condition of the pumps and outlets will affect the quality of the water and the efficiency of how the household can access and use the water. A well-maintained system can also protect against long-term damage.
  • Our report found that in homes with pumps installed, 5 per cent were not functioning and 18 per cent of properties inspected were reported to have leaky pipes.

  1. It’s time to desludge
  • Standards Australia recommends that households organise the removal of sediment with a qualified contractor once every two to three years.
  • You probably don’t want to be dealing with this water.

The report also advises should check to make sure tank foundations are even, and that the tank has a reliable water switch.

If you would like to review the report in full you can find it here.


Climate projections show Australia is heading for a much warmer future

Beach scene

Future Sydney? Climate projections show Sydney’s climate could end up more like Brisbane’s. Image: Kevin Gibbons/Flickr, CC BY

By Kevin Hennessy, CSIRO and Penny Whetton, CSIRO

Australia is on track for up to 1.7C of warming this century if the world curbs its greenhouse emissions, but under a worst-case scenario could see anything from 2.8C to 5.1C of warming by 2090, according to new climate change projections released by the CSIRO and the Bureau of Meteorology.

The projections are the most comprehensive ever released for Australia. They are similar to those published in 2007, but based on stronger evidence, with more regional detail. These projections have been undertaken primarily to inform the natural resources management sector, although the information will be useful for planning and managing the impacts of climate change in other sectors.

Possible futures

The new report draws on climate model data used by the Intergovernmental Panel on Climate Change (the IPCC). The Fifth IPCC Assessment Report (AR5), released in 2013 and 2014, used a range various greenhouse gas and aerosol scenarios to project future climate change.

Over the past 10 years, carbon dioxide emissions have been tracking the highest IPCC emission scenario (known as RCP8.5). If there is limited international action to reduce emissions, then projections based on the highest scenario may be realised.

However, if emissions are significantly reduced over the coming decades, then intermediate emissions (RCP4.5) might be feasible. Following the low emissions scenario (RCP2.6) would be very challenging given the current trajectory of carbon dioxide emissions.

How does Australia compare?

By late in this century (2090), Australia’s average warming is projected to be 0.6 to 1.7C for a low emission scenario, or 2.8 to 5.1C under a high emission scenario.

The warming under the high scenario is similar to the global average warming of 2.6 to 4.8C under the high emission scenario reported by the IPCC AR5. However, inland areas of Australia will warm faster than coastal areas.

For example, the Rangelands of inland Australia warm by 2.9-5.3C by 2090 under high emissions, while the East Coast, including Sydney and Brisbane, warms by 2.7-4.7C.

Map showing climate projections

This map shows the annual mean temperature for present climate (A), and late 21st century (B). In each panel the 14C, 20C, and 26C contours are shown with solid black lines. In (B) the same contours from the original climate are plotted as dotted lines to provide the clearest depiction of the shifts in climate.

Historical context

The new projections should be viewed in the context of what has already been observed. Australia has become 0.9C warmer since 1910. Rainfall has increased in northern Australia since the 1970s and decreased in south-east and south-west Australia.

More of Australia’s rain has come from heavy falls and there has been more extreme fire weather in southern and eastern Australia since the 1970s. Sea levels have risen by approximately 20 cm since 1900.

In future, Australia’s average temperature will increase and we will experience more heat extremes and fewer cold extremes. Winter and spring rainfall in southern Australia is projected to decline while changes in other regions are uncertain.

For the rest of Australia, natural climate variability will predominate over rainfall trends caused by increasing greenhouse gases until 2030. By 2090, a winter rainfall decrease is expected in eastern Australia, but a winter rainfall increase is expected in Tasmania.

Historical climate data can be used as an analogue for the future. The analogue could be a location that currently has a climate similar to that expected in another region in the future.

For example, for a warming of 1.5-3.0C and a rainfall decrease of 5-15%, Melbourne’s climate becomes similar to that of Clare in South Australia, Sydney becomes more like Brisbane, and Brisbane becomes more like Bundaberg in inland Queensland.

Extreme rainfall events that lead to flooding are likely to become more intense. The number of tropical cyclones is projected to decrease but they may be more intense and possibly reach further south. Southern and eastern Australia is projected to experience harsher fire weather. The time in drought will increase over southern Australia, with a greater frequency of severe droughts.

A projected increase in evaporation rates will contribute to a reduction in soil moisture across Australia. There will be a decrease in snowfall, an increase in snowmelt, and therefore reduced snow cover.

Sea levels will continue to rise throughout the 21st century and beyond. Oceans around Australia will warm and become more acidic.

What will Australia look like?

Freshwater resources are projected to decline in far south-west and far south-east mainland Australia. Rising sea levels and increasing heavy rainfall are projected to increase erosion and inundation, with consequent damage to many low-lying ecosystems, infrastructure and housing.

Increasing heat waves will increase risks to human health. Rainfall changes and rising temperatures will shift agricultural production zones. Many native species will suffer from reduced habitats and some may face local or even global extinction.

The most vulnerable regions/sectors are coral reefs, increased frequency and intensity of flood damage to infrastructure and settlements, and increasing risks to coastal infrastructure and low-lying ecosystems.

While reductions in global greenhouse gas emissions would increase the chance of slowing climate change, adaptation is also required because some warming and associated climate changes are unavoidable.

The Conversation

This article was originally published on The Conversation.
Read the original article.


A shark’s tale: is there something fishy in the waters off Newcastle?

shark 4

A shark off Burwood beach, Newcastle, on Thursday. Pic: Peter Stoop, courtesy Heliservices Newcastle

The coastal city of Newcastle is in the midst of a media frenzy, thanks to a string of shark sightings close to popular swimming beaches.

A 15 kilometre stretch of beaches has now been shut for a record six consecutive days, with lifeguards and police craft reporting shark sightings seemingly by the hour. Of most concern have been a purportedly 5 metre, 1,700kg White shark that has been lingering along the coastline; and what is suspected to be a 3 metre tiger shark that was photographed attacking and killing a small dolphin only 50 metres from the shore yesterday (warning: graphic images).

While no attacks on humans in the area have yet been recorded, the sharks have become national celebrities in their own right, with widespread media coverage and commentary. There has even been a Twitter account set up for the @Newy_Shark (which is one account you probably don’t want to be “followed” by).

So what’s the deal here? Are we seeing the real-life return of Jaws? Has a curse been struck down upon the town of Newcastle by Poseidon himself? Is a Sharknado next?

Our resident White shark expert, Barry Bruce, knows a thing or two about these ancient predators. He is one of Australia’s pre-eminent authorities on the species and is the head of our White Shark Research Program. But he is perhaps most famously known for having one of Finding Nemo’s most famous characters named after him.

According to Barry, the story behind Newcastle’s shark saga is far less salacious. Thankfully, we’re not gonna need a bigger blog.

The coastline just north of Newcastle (stretching from the appropriately named Stockton Bight to the even tastier-sounding Seal Rocks) is famously known as being a nursery ground for White sharks. These juveniles are usually about 2-3 metres in length, and a tagging program undertaken by Barry and his team has shown that they are more than prevalent in the area.

Satellite positions for 19 tracked juvenile White sharks in the Port Stephens region 2007 – 2010. Registered positions are colour-coded for each shark. Dotted pink line denotes approximate boundary of the White shark nursery area.

Satellite positions for 19 tracked juvenile White sharks in the Port Stephens region 2007 – 2010. Registered positions are colour-coded for each shark. Dotted pink line denotes approximate boundary of the White shark nursery area.

Seeing a larger sized White in this area, like the infamous #NewyShark, is slightly less common, but still not at all unusual.

Large White sharks are well known to move up and down the New South Wales coastline, stopping in certain areas when food is prevalent. White sharks have been exhibiting this exact behaviour for countless millennia – it is only when they stop near a heavily populated area like Newcastle that we would notice.

But these are nomadic creatures, and they won’t stay in one spot for too long. We know through collaboration with our colleagues in New Zealand that white Sharks will travel as far north as the Great Barrier Reef – and even across the Tasman to NZ – in a span of just months.

Bruce and his team tagging a white shark with an acoustic tagging device.

Barry and his team tagging a white shark with an acoustic tagging device.

Barry puts the current concentration of sharks in Newcastle purely down to natural variability. Sharks go where the food goes – if there are more sharks in one area at one point in time, it means there will be less in others.

And while we’re in the mood for debunking myths, here’s another one: dolphins are just as much a food source for sharks as are any other species of their size. While it is uncommon for us to observe – and the images were undeniably distressing – sharks are well-known to attack dolphins. Unfortunately, what Flipper taught us was wrong.

More than anything, Barry says that this is a positive advertisement for the health of marine ecosystems in Australia. That there is a large enough food source to sustain shark populations is a good thing, and should be celebrated.

But of course, it is important for beachgoers to take advice from authorities when entering the water. While this is a natural spectacle that should be enjoyed, it is advisable to do so from a distance – and on land. In time it will run its course, and we can all return to the water.

White shark fast facts:

    • A common mistake people make is calling these awesome creatures, ‘Great White Sharks’, it’s actually just ‘White shark’ (Carcharodon carcharias). But we still think they’re still pretty great.
    • Sharks play a vital ecosystem role as top predators. Declines in top predators can cascade through the food web, seeing some species groups increase while eliminating others.
    • We have one of the most comprehensive White shark research programs in the world, with over 250 tagged White sharks in Australian waters. Check out a few shark tracks on our website.
    • Our tagging program provides us with a good idea of migration patterns – we know for example that there is an East and a Southwest population.
    • Our research on White sharks is a collaborative project funded under the Australian Government’s National Environmental Research Program.
    • We tag these beauties in a very humane way – in a sling, in the water:


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