Category Archives: Northern Territory

Addressing ghost nets in Australia and beyond – update of EMR feature

Britta Denise Hardesty, Riki Gunn and Chris Wilcox

[Update of EMR feature  – Riki Gunn, Britta Denise Hardesty and James Butler (2010) Tackling ghost nets: local solutions to a global issue in Northern Australia, Ecological Management & Restoration, 11:2, 88-98. https://onlinelibrary.wiley.com/doi/10.1111/j.1442-8903.2010.00525.x]

Key words.  derelict fishing nets, ghost gear, GGGI, Indigenous livelihoods

Figure 1. Dead turtle caught in a derelict ghost net. (Photo: Jane Dermer, Ghost Nets Australia)

Introduction. The focus of our 2009 feature was to highlight the work of Indigenous rangers in addressing the local but widespread problem of abandoned, lost or derelict fishing gear (ALDFG) in Northern Australia, particularly ‘ghost nets’ that are carried on the currents and continue to fish long after they are no longer actively used (Figs 1-4). We also aimed to raise awareness of the efforts required to address this complex issue, whilst highlighting the work of Indigenous rangers working in the region.  The feature reported ghost net removal efforts taking place in Australia’s Gulf of Carpentaria – which, by 2009, involved the removal of 5532 nets by over 90 Indigenous rangers from more than 18 Indigenous communities.  This highlighted the transboundary nature of the ghost gear issue, and identified that most nets likely originated from beyond Australia’s waters.

Figure 2. Napranum ranger Philip Mango releasing juvenile turtle trapped in ghost net. (Photo: Ghost Nets Australial)

Further work. Since 2010, the understanding of and approaches to addressing the derelict fishing gear issue have increased substantially. This has been reflected both in domestic efforts within Australia, and more broadly in the international community.

Domestically, in the last decade, the ranger program across northern Australia has evolved and grown, enabling more Indigenous people to remain culturally connected to their land and sea country through meaningful employment.  Ranger activities generally involve a range of restoration activities including feral and weed management, in addition to (for  coastal groups) ghost net removal. Across northern Australia, Indigenous ranger groups continue to remove nets on their country, demonstrating the success of the initial program supported by the Australian government. To date, nearly 15,000 ghost nets (three times the number reported in 2010) have been removed from the region. The net removal program has extended beyond Ranger groups working in the Gulf of Carpentaria to include the Torres Strait, the western part of the Northern Territory Coast, and parts of the Kimberly coastline in Western Australia.

Globally, the world is focused on the United Nations Sustainability Development Goals (SDGs) which aims to provide a ‘shared blueprint for peace and prosperity for people and the planet, now and into the future’ (https://sustainabledevelopment.un.org/sdgs).

A key focus for the SDGs is to help preserve the world’s oceans, a topic which touches on food security, poverty and economic growth, among other goals. Ensuring fishing practices are aligned with these goals includes reducing gear losses into the marine and coastal environment. In recognition of the issue and to end ALDFG, there is now a multi-stakeholder alliance of fishing industry, private sector, multinational corporations, non-government organizations, academics and governments, the Global Ghost Gear Initiative (GGGI), which is focused on solving the problem of abandoned, lost and derelict fishing gear worldwide. Both CSIRO and GhostNets Australia were founding members of this alliance and have been instrumental in engagement and scientific endeavours which inform the GGGI.

Fig 3. An enormous effort is invested by Indigenous rangers in removing ghost nets from beaches along the northern Australian coastline (Photo: World Animal Protection/Dean Sewell)

Based on collaborative research between GhostNets Australia and CSIRO, it was determined that the primary source of derelict nets washing ashore along Australia’s northern coastline was the Arafura Sea. Engagement with fishers in the region through a series of workshops identified that major causes of gear loss included snagging of nets and over-capacity in the region. We also identified opportunities to help resolve ghost net issues in the region, though stakeholder engagement, points of intervention and livelihood tradeoffs. Much of this overcapacity and overcrowding has been attributed to illegal, unreported and unregulated (IUU) fishing. Subsequently, Indonesia went through a substantial change in practices with regards to allowing foreign vessels in their waters, effectively closed their borders to foreign fisheries operators. Anecdotally, information from multiple ranger groups in Northern Australia suggests that this highly publicized and significant change in practice has resulted in a substantial decrease in the number of ghost nets washing ashore along at least part of the northern Australian coastline.

Another outcome from the collaborative research effort was a new understanding based on deep citizen science engagement and modelling to identify potential high risk areas where ghost nets were likely to cause the most harm to turtles. In this work, we were able to suggest interdiction points for ghostnets, before they entered the Gulf of Carpentaria where they were likely to kill wildlife. We also identified the nets that were most harmful to wildlife and we estimated that nearly 15,000 marine turtles had likely been killed by derelict nets in the region.

There have also been some technological improvements in this area. These fall into both reporting and in tracking nets. Electronic data collection has improved the quality of data collection and can ensure errors are minimised. Development of the tool has also been designed such that those with reduced literacy are also able to collect valuable information, a feature that can be important in many communities. Using icons and photos to help identify nets improved data reliability.

Also within Australia, alternative livelihoods programs such as Ghost Net Gear evolved into the Ghost Net Art Project where the art works have excited the International art community.  This has resulted in purchases by many internationally renowned purveyors of artwork including the British Museum, the Australian National Museum and the Australian Maritime Museum. Works from Indigenous artists can also be seen at Australia’s Parliament House, and exhibitions have taken place in Monaco, Alaska, Singapore and France as well as in numerous national and regional galleries around Australia. A commemorative stamp was even made from the Ghost Nets artwork that lives in the Australian National Museum.

Figure 4. Large nets can become entangled in coastal vegetation. (Photo: World Animal Protection/Dean Sewell)

Future directions. While GhostNets Australia has not formally continued as a non-governmental organization, many of the components initiated through the program have continued and grown through time, as exemplified above. This early work also helped springboard CSIRO’s engagement in capacity building with the Indonesian government to tackle Illegal, Unreported and Unregulated (IUU) fishing. This had led to a strong research collaboration relationship between the two countries, with a shared goal of reducing IUU fishing, building capacity on marine resource management, and improved monitoring, control and surveillance efforts in Indonesia.

CSIRO is also involved in an aerial (re)survey of the coastline across Northern Australia. In affiliation with World Animal Protection and Norm Duke and Jock Mackenzie from James Cook University, we are looking at changes in the number of ghost nets along the shoreline (Figs 3 and 4). Stereo images were recorded along the entire coastline and we are comparing ghost nets observed across the region with two other aerial surveys that have taken place in the last decade. The team have just completed flights (September 2019), so we are looking forward to analysing the images and comparing ghost net numbers across the region.

ContactDenise.hardesty@csiro.au; CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia. rikigunn1@outlook.com; chris.wilcox@csiro.au

The rise of invasive ant eradications since the success of the Kakadu project  – UPDATE of EMR feature

Benjamin D Hoffmann

[Update of EMR feature – Hoffmann,  Benjamin D and Simon O’Connor (2004) Eradication of two exotic ants from Kakadu National Park. Ecological Management & Restoration, 5:2, 98-105. https://onlinelibrary.wiley.com/doi/10.1111/j.1442-8903.2004.00182.x]

Key words. pest species management, invasive species, biosecurity

Figure 1. Kakadu staff in 2001 spreading formicide over a super-colony of African Big-headed Ant. This involved a team of people, aligned in a row, walking from one edge of the infested area to the other in parallel paths. (Photo courtesy of Simon O’Connor.)

Introduction. Invasive species management, especially eradications, has been at the forefront of biodiversity conservation gains over the past two decades. For example, over 1,200 invasive vertebrate eradications have been achieved on over 800 islands worldwide and the conservation benefits of such actions have been overwhelmingly positive and often dramatic. Efforts against invasive ants have also been particularly notable over the past two decades, with ants now being the second-most eradicated taxa globally having been eradicated from more than 150 locations, with the largest eradication covering 8300 ha. Two decades ago there were only 12 confirmed ant eradications using modern baits with a combined area totalling a mere 12 ha.

As reported in our original EMR feature, the last treatments against two invasive ants in Kakadu National Park, northern Australia: The African Big-headed Ant (Pheidole megacephala) and the Tropical Fire Ant, (Solenopsis geminata) were conducted in 2003; and the ants were declared eradicated two years later (Hoffmann & O’Connor 2004). At the time this was a globally significant eradication, and the positive outcome was a partial catalyst for the creation of many other relatively small exotic ant eradication attempts around Australia, including against Tropical Fire Ant on Melville island, and African Big-headed Ant on Lord Howe Island. Incidentally, the work coincided with the approximate timeframe of when two other highly invasive ant species were first detected in Australia: Red Imported Fire Ant (RIFA) (Solenopsis invicta), and Electric Ant (Wasmannia auropunctata), prompting the initiation of two massive national cost-shared eradication programs. One of these, the RIFA program, has become Australia’s second-most expensive eradication program at AUD $428 million as of at July 2019. Together, all of these actions put ants high on Australia’s biosecurity and environmental management radars, prompting the development of Australia’s Tramp Ant Threat Abatement Plan and yet even more eradication programs.

Figure 2. Ant bait being dispersed aerially by helicopter using an underslung spreader and side-mounted dispersers. (Photos Ben Hoffmann)

Further advancements in ant eradication programs.  As Australia’s eradication programs became more numerous and larger, it became apparent very quickly that the methodologies and technologies available were insufficient to achieve success in the increasingly challenging conditions being encountered. In response, over the next two decades, there has been an impressive range of advancements that significantly improved our capacity to manage and eradicate invasive ant incursions.

The biggest issue was that work needed to be conducted over such large or inaccessible areas that ground-based work (Fig 1) was not feasible. So, treatments quickly became aerial, using multiple helicopter-based delivery platforms (e.g. underslung buckets and side-mounted hoppers, Fig 2). Even so, there have been locations that are too remote, too small, or too difficult (ie cliffs) to treat using a helicopter. To meet this challenge, in just the last five years treatments have been conducted for the first time using drones, and there is a great focus now to improve the technology so that it becomes more cost effective and more autonomous (Fig 3). This is occurring at such a pace that just a few years ago drones could only operate for a few hours at most on battery power, and only carry a few kilograms. This year we will be using a drone with unlimited flying capacity (petrol driven) that can lift 70 kg per load.

Figure 3. The Fazer with side-mounted bait carriers that can lift up to 40kg of payload. This is soon to be superseded by a drone that can lift a 70k g payload. (Photo Ben Hoffmann)

Assessments for the presence of ants, either before or after treatments, was originally very time consuming, involving teams of people walking ground very slowly and often utilising thousands of attractive lures (Fig 4). At most, only small ant populations (about less than 20 ha) within good working environments (ie open landscapes) could be assessed using teams of people, and it took large amounts of time. It was found very quickly that detector dogs could be trained on the scent of each ant species, and a single dog could cover more than five times the area of a team of people in a single day with greater efficacy (Fig 5). There are now more than 20 detector dogs operating in Australia and New Zealand that have been trained on the scent of four ant species. But even a team of dogs cannot fully cover entire areas at the landscape-scale, such as is the case for the RIFA program, especially in areas with long grass or rugged terrain. One of the saving technologies for the RIFA program has been the development of a multi-spectral sensor and associated algorithms that can identify RIFA nests from imagery captured by remote sensing (Fig 6). This allows program staff to assess just a few identified point locations in a landscape rather than the entirety of landscapes, to determine RIFA presence or absence. The next envisaged step is the development of biosensors that can detect the odours of target ant species, just like detector dogs, and with time these will become small enough to be transported by small drones throughout landscapes to detect ants.

Figure 4. An area covered with hundreds of flags marking spoonfulls of catfood being used as lures to attract African big-headed ant to assess eradication success or failure. (Photo Ben Hoffmann)

Figure 5. An ant detector dog searching for the presence of Red imported fire ant. (Photo courtesy of The State of Queensland (Department of Agriculture and Fisheries 2010–2019))

Australia was caught particularly unprepared two decades ago when the two new exotic ant species were detected for the first time because there were no baits registered for their management in Australia, so legally there were no treatment products that could be used. Even with the implementation of Emergency Use Permits for some unregistered products, as well as the use of the few products that were available for other species, it was often found that individual products could not be used in particular circumstances, especially around water, within crops and on organic farms. Additionally, available baits often did not have high efficacy. With time many baits (comprised of combinations of an attractive food laced with an active constituent) have been formulated and tested providing a greater array of baits that can be used on any new incursion and in numerous settings. The most recent has been the development of hydrogel baits that essentially deliver a liquid product in a solid form.

Figure 6 a and b. Multi-spectral camera flown underneath a helicopter to detect Red imported fire ant nests. (Photos courtesy of The State of Queensland (Department of Agriculture and Fisheries) 2010–2019)

Among the numerous advances described already, possibly the greatest development is on the threshold of becoming a reality, in the form of genomic solutions for individual species. RNA interference, and gene-drive technology are rapidly being developed for a suite of economically important species, and ants are among the taxa that are highest on the priority list as targets for this research. At best, these genomic advances promise to provide species-specific solutions, thereby alleviating the current non-target issues of using toxicants.

Conclusion. Our ability to eradicate ants has improved dramatically over the past two decades, with technologies and methodologies available now that were as yet not thought of back when our work was conducted in Kakadu National Park. New programs are constantly arising, and forging ahead in increasingly challenging situations, and a great deal of effort is placed in information-sharing among programs. Simultaneously there is a sustained focus to improve biosecurity at Australia’s borders, as well as throughout our region to help prevent the need for eradications in the first place.

Contact. Ben Hoffmann, Principal Research Scientist, CSIRO Health & Biosecurity (PMB 44 Winnellie NT 0822 Australia; Tel: +61 8 89448432; Email: Ben.Hoffmann@csiro.au).