Ghost nets and other forms of marine pollution come under the spotlight during the global Plastic Free July movement, writes DENISE CULLEN.
Ghost nets are one of the most damaging types of plastic marine debris.
For good reasons, these pieces of lost, dumped or abandoned fishing gear have been described as “death traps”, “silent killers” and a “global problem”.
According to the Australian Marine Conservation Society, up to 14,600 turtles were caught in 8,690 ghost nets found across northern Australia in just seven years.
And that’s before you start counting sharks, dolphins, rays, whales, birds and other sea creatures who become ensnared.
Ghost nets can drift significant distances across the ocean.
Due to the prevailing currents, Queensland’s Cape York Peninsula and the Northern Territory coastline south of the Gove peninsula are considered Australia’s ghost net ‘hot spot’.
Some ghost nets stretch for hundreds of metres in length and are bigger than a football field; others, though much smaller, can still be deadly.
The problem is only getting worse, with up to 2% of all fishing gear lost to the ocean annually.
Yet new technology is being harnessed to help identify and clean up ghost nets with a speed and precision that couldn’t be envisaged just a few years ago.
Camera traps of the sky
Drones used in combination with artificial intelligence (AI) are the latest tools being used to combat the significant problem of ghost nets across the Northern Territory coastline.
Environmental scientist Aliesha Hvala, who works as an unmanned aerial vehicle (UAV) research officer within the North Australia Centre for Autonomous Systems at Charles Darwin University (CDU), says that combining drone technology with AI has been a “gamechanger”.
As part of the Australian Marine Parks’ Ghost Net Innovative Solutions program, Hvala has for the past year been working with Anindilyakwa Land and Sea Rangers to address the issue across the Groote Archipelago in the Gulf of Carpentaria.
“Innovative technology such as drones can be used to bridge the gap of remoteness in an efficient and cost-effective manner,” Hvala told me.
Previously, the work was done with helicopters, with a reliance on the human eye to spot nets while travelling at speed and over rugged and complex coastal terrain, says Benjamin McArdle, Aquatic Biosecurity Officer for the Anindilyakwa Land and Sea Rangers.
Drones offer a user-controlled solution for ranger groups and more autonomy on country that’s not necessarily linked to expensive equipment like helicopters, or restricted by seasonal access, Hvala adds.
The CDU project involves using long-distance uncrewed autonomous aircraft to capture images which reveal the location of ghost nets across hundreds of kilometres of NT coastline.
The drones thus function as a “camera trap in the sky”, she says.
Analysing images
Traditionally, researchers relied on manual image analysis, which is tedious, time-consuming, and impractical as the volume of visual data increases.
“To manually go through all of these photos every time you do a survey, you’re almost delaying the efficiency of being able to use the information extracted from those photos,” Hvala explains.
“The goal of incorporating AI was to increase the efficiency of translating large volumes of spatial data into actionable information that can be used within days or weeks rather than months later.”
The longer that ghost nets linger in the environment, the higher the risk that they will negatively impact wildlife. In some cases, they may even re-float and be deposited elsewhere.
Now, after the drones capture high resolution images of the coastline, a real-time object detection algorithm dubbed YOLO (“You only look once”) scans the images to detect the presence of ghost nets which might otherwise be difficult for searchers on the ground to spot.
The typical garish blue, green or cyan colour of ghost nets makes them stand out against the natural landscape, even if the net is mostly buried under sand, tangled in rocks, or wrapped around a tree.
Fragments as small as 50 centimetres can be identified in this way.
Extracting both imagery and GPS coordinates for each net and providing them to rangers allows them to plan retrieval operations, which is vital in remote and difficult-to-access coastal areas.
“Rather than trying to have to comb the coastline to try to find them, can go directly to that location,” Hvala says.
The targeted approach reduces search time and fuel consumption.
It also allows rangers to strategically plan labour and equipment requirements.
“(It) increases our chance of retrieving the nets, knowing what equipment we will need to take with us,” says McArdle.
“We tested this late last year with great success retrieving 15 ghost nets in just a few hours.
“These nets were then transported 70 nautical miles back to our ranger base on our ghost net vessel, Jarrangwa.”
Hvala says the research team is still trialling different models and refining their workflow.
Urgent issues
As a $15 million initiative to help Indigenous rangers remove ghost nets and other ocean plastics from northern Australia’s beaches comes to an end, there are calls to continue funding this important work.
“Currently, we have no funding to continue the ghost net and marine debris program (and) no indication as to if or when funding will be available,” says McArdle.
While Hvala’s research will continue, she strongly supports further training for ranger groups in drone operation and data interpretation.
“Building local capacity ensures that drone-based surveys can be conducted regularly, enabling rangers to collect coastal imagery that supports long-term monitoring programs,” she says.
“The funding may stop but the rubbish won’t.”
Though ghost nets represent a formidable problem globally, they comprise only 10 per cent of all marine pollution.
How to combat ever-increasing amounts of waste that harm marine ecosystems was among the most pressing problems highlighted during the 2025 United Nations Ocean Conference in Nice, France, during June.
Hvala first became interested in the issue when, during a clean-up, she counted 25 lighters in a single one-square-metre patch of sand – on a stretch of beach that was 10 kilometres long.
“Once you see the issue of marine waste in northern Australia, it’s very confronting,” she says.
“It’s not a couple of bottles that might be washing up. It’s tonnes of waste. It’s everything you can think of.
“It’s very hard to unsee that.”
OTHER GHOST NET INNOVATIONS
The problem of ghost nets is being addressed with a combination of regulation, retrieval, recycling, and repurposing:
REGULATION
The Australian Maritime Safety Authority is using Plastic Free July to highlight the problem of marine pollution. It reminds the owners and operators of ships and domestic commercial vessels that, under the Protection of the Sea Act and Marine Order 95 (Marine pollution prevention – garbage), it is illegal to discharge plastic waste (including fishing gear) into the water.
RETRIEVAL
Project Recon by Tangaroa Blue is using retrieved and repurposed satellite technology to track and remove ghost nets. Speaking at the 2023 Citizen Science conference on Queensland’s Sunshine Coast, Heidi Tait, CEO of Tangaroa Blue Foundation, identified that these solar-powered “smart buoys” could be used to tag and track floating ghost nets before their position was lost. Crews could then move in to remove them, even weeks later, through accurate, updated location information.
RECYCLING
Sea Shepherd’s Ghost Network project sees the organisation partner with businesses to repurpose and recycle recovered fishing gear collected by its patrols. For example, in partnership with iMilani, a family-owned company based in Vicenza, Italy, the organisation has developed a way to repurpose harmful debris into Sea Turtle Crates designed to safely transport and rehabilitate injured sea turtles, forming a crucial tool now onboard all Sea Shepherd vessels.
REPURPOSING
Research published in 2025 in Construction and Building Materials identified that ghost nets could be used as additives in porous asphalt mixtures used in road construction. The researchers found that recovered nets may represent an alternative to commercial fibres made of polymers, glass fibres, cellulose, and carbon, reducing the need for their production and consumption, while promoting responsible use of a ‘waste’ resource.
Elsewhere, Indigenous artists are using ghost nets and other discarded materials to create artworks. The Australian Museum, for instance, has ghost net sculptures in its collection. These artworks can tell traditional stories in a new way and raise further awareness of the issue of marine pollution. The creation of artworks may also help to support individual artists and their communities financially, or provide funding for further clean-up efforts.