Blog

14 January 2013

Phantom fishing targets turtles in northern Australia CSIRO scientists working with GhostNets Australia and Indigenous rangers are identifying hotspots where lost fishing nets are threatening our marine biodiversity.

Worldwide, around 640 000 tonnes of fishing gear is lost or discarded each year. These ‘ghostnets’ can continue fishing for decades, entangling huge numbers of marine animals, including threatened and commercially valuable species.

Ghostnets, originating mainly from fisheries in Asia and Australia, are a particular problem in Australia’s Gulf of Carpentaria, where they can reach densities of up to three tonnes/km, among the highest recorded worldwide.

“Our research goes beyond discovering where ghostnet fishing is taking place, to actually estimating its impact on biodiversity, in particular on threatened marine turtles,” Dr Denise Hardesty of CSIRO said.

“Using a model of ocean currents and data collected by Indigenous rangers on the number of ghostnets found during beach cleanups, we simulated the likely paths ghostnets take to get to their landing spots on beaches in the Gulf of Carpentaria,” Dr Hardesty said.

“Combining this with information about the occurrence of turtles in the area, we found that entanglement risk for turtles is concentrated in an area along the eastern margin of the Gulf and in a wide section in the southwest extending up the west coast,” she said.

“Most ghostnets enter the Gulf from the northwest and move clockwise along its shore. This means we can help protect biodiversity in the region by intercepting nets as they enter the Gulf, before they reach the high density turtle areas along south and east coastlines,” she said.

Australia is home to six of the world’s seven threatened species of marine turtle. During a recent cleanup of ghostnets on beaches in the Gulf, 80 per cent of animals recorded in nets were marine turtles, including Olive Ridley, Hawksbill, Green and Flatback turtles.

“Our predictions of the distribution of turtles washing ashore entangled in ghostnets matched the actual frequencies of turtles found in ghostnets during beach surveys, suggesting our model is accurate,” Dr Hardesty said.

Ghostnets are a global problem, capturing seabirds, marine mammals and sea turtles worldwide. Lost or abandoned fishing gear makes up only 20 per cent of marine debris but has a disproportionate effect because it is designed to capture wildlife.

“Our research shows that combining models of marine debris with species occurrence data could identify global hot spots for impact, helping pinpoint where prevention and clean-ups could really make a difference to biodiversity,” Dr Hardesty said.

This research used information on ocean currents generated by the BLUElink Ocean Data Assimilation System to simulate the paths of ghostnets.

‘Ghostnet impacts on globally threatened turtles, a spatial risk analysis for northern Australia [external link]‘ was published by CSIRO and GhostNets Australia in the January 2013 online early issue of Conservation Letters [external link].

Image: A turtle washed ashore caught by a ghostnet (Image: Alistair Dermer)

The 21st century is now a teenager. We prospered. We suffered. But most of all, we survived. Here’s to 2012 and the year ahead. 2012 was a remarkable year, especially for science. There were world firsts and breakthroughs. The story of the Higgs boson definitely made the top of many lists. The relentless march of scientific progress is always long and 2013 will mark another chapter.

Where will the science firsts and breakthroughs come from? Of course we can never predict where the big science stories will come from. And that is part of the beauty. But at least 2012 has told us where to look.

The NASA Mars rover Curiosity still treks on. NASA’s Mars Science Laboratory Project is using Curiosity during a two-year prime mission to assess whether areas inside Gale Crater ever offered a habitable environment for microbes. So there are still much to discover on the red planet. Curiosity explores the Glenelg region during the early part of the year. Then it will venture on, a 6 to 9 month journey across the martian landscape taking in the sights and seeing what is there to discover.

In 2013 expect the comet Ison to garner some column inches towards the back end of the year. In early 2013 October it will pass very near Mars and possibly be visible to rovers and orbiting spacecraft. The newly discovered comet could develop a spectacular tail, becoming as bright as the full Moon as it passes by our Sun. The comet is currently falling toward the Sun from between the orbits of Jupiter and Saturn. There is a chance it won’t survive this encounter. Whatever survives will then pass nearest the Earth in late 2013 December.

In 2012, disaster relief made prime time news. In our ever-changing climate, disasters are becoming more of a recurring topic. Hopefully, 2013 will give us a little bit more foresight in this department. We have to mitigate better, and lessen the damage and destruction of human life.

In 2013, we shall eradicate guinea worm. Polio is also on the list, but progress is slow on that one. Smallpox, rinderpest, and guinea worm makes three. More remarkable than the other two because we will do it without any cure or drug treatment. Our science has produced no miracle cure, no vaccine, no treatment, and yet guinea worm will be gone.

We are constantly at the frontiers of science and we don’t know quite what to expect. What we can be sure of is that as the news breaks, the science will be covered by bloggers and journalists, at both ends of this new media scale. The science writing ecosphere has seen very little change in 2012. The furniture was rearranged as some writers found new homes for their blogs. But for the most part, the living room stayed the same. If anything there was a proliferation of new voices to add to the mix. PLoS Blogs added a nice mix of public health bloggers to their roster. Mind the Science Gap continues to prove to be a great experiment in letting new voices into the science writing game. A new batch of bloggers takes to its site in January for another 10 week stint. Certainly here at Australian Science we’ve added a long list of new bloggers. Expect this to continue.

So here’s looking forward to what 2013 has in store.

“Monster” outflows of charged particles from the centre of our Galaxy, stretching more than halfway across the sky, have been detected and mapped with CSIRO’s 64-m Parkes radio telescope. Corresponding to the “Fermi Bubbles” found in 2010, the outflows were detected by astronomers from Australia, the USA, Italy and The Netherlands. The finding is reported in the Jan 2 issue of Nature.

“These outflows contain an extraordinary amount of energy — about a million times the energy of an exploding star,” said the research team’s leader, CSIRO’s Dr Ettore Carretti.

But the outflows pose no danger to Earth or the Solar System.

The speed of the outflow is supersonic, about 1000 kilometres a second. “That’s fast, even for astronomers,” Dr Carretti said. “They are not coming in our direction, but go up and down from the Galactic Plane. We are 30,000 light-years away from the Galactic Centre, in the Plane. They are no danger to us.”

From top to bottom the outflows extend 50,000 light-years [five hundred thousand million million kilometres] out of the Galactic Plane. That’s equal to half the diameter of our Galaxy (which is 100,000 light-years — a million million million kilometres — across).

Seen from Earth, the outflows stretch about two-thirds across the sky from horizon to horizon. The outflows correspond to a “haze” of microwave emission previously spotted by the WMAP and Planck space telescopes and regions of gamma-ray emission detected with NASA’s Fermi space telescope in 2010, which were dubbed the “Fermi Bubbles.”

The WMAP, Planck and Fermi observations did not provide enough evidence to indicate definitively the source of the radiation they detected, but the new Parkes observations do.

“The options were a quasar-like outburst from the black hole at the Galactic Centre, or star-power — the hot winds from young stars, and exploding stars,” said team member Dr Gianni Bernardi of the Harvard-Smithsonian Center for Astrophysics, in Cambridge, Massachusetts. “Our observations tell us it’s star-power.”

In fact, the outflows appear to have been driven by many generations of stars forming and exploding in the Galactic Centre over the last hundred million years.

The key to determining this was to measure the outflows’ magnetic fields.

“We did this by measuring a key property of the radio waves from the outflows — their polarisation,” said team member Dr Roland Crocker of the Max-Planck-Institut fuer Kernphysik in Heidelberg, Germany, and the Australian National University.

The new observations also help to answer one of astronomers’ big questions about our Galaxy: how it generates and maintains its magnetic field. “The outflow from the Galactic Centre is carrying off not just gas and high-energy electrons, but also strong magnetic fields,” said team member Dr Marijke Haverkorn of Radboud University Nijmegen in The Netherlands.

“We suspect this must play a big part in generating the Galaxy’s overall magnetic field.”