At Seal Rocks, two kilometres off the Nobbies on Phillip Island in Victoria, a team of marine researchers is deploying cutting-edge thermal imaging to spot something human eyes cannot easily see: fishing line wrapped around the necks and flippers of fur seals struggling to survive in the colony.
Seal Rocks is home to 20,000 seals—one-quarter of the entire population of Australian fur seals. Yet this abundance masks a crisis.An estimated 60 Australian fur seals are affected by entanglement at Seal Rocks, and the true toll may be higher becausefishing line entanglement is almost impossible to see via drone or from a boat.
The problem is immediate and severe.At least 0.3% of seals in this area are entangled in marine debris, causing terrible injuries and contributing to a painful death; 69% of entanglements are in fishing gear.Over time, entanglements become tighter and tighter, cutting through skin and often embedding in the skin, causing starvation, infections, strangulations, drowning, increased vulnerability to predators or a combination of effects.
The bottleneck has been practical:only 50% of the affected population can be rescued. Finding an entangled seal in a crowded colony of thousands requires either spotting obvious entanglement from a boat—risky and often unsuccessful—or discovering it by chance during field visits. Thin monofilament line, nearly invisible against fur and sea, slips past traditional observation methods.
Phillip Island Nature Parks is delivering a three-year project in collaboration with Monash University and other partners to explore long-term effects of marine debris on Australian fur seals.The team has successfully completed 42 drone surveys utilising state-of-the-art thermal sensors over Seal Rocks to see if this technology can be used for better entanglement detection. Thermal imaging, which captures heat signatures, makes previously undetectable entanglements visible because the wound sites warm differently than surrounding fur.
This collaborative approach will improve capacity to rescue seals by developing better tools for identifying entanglement, such as testing thermal-imaging drones. The research extends beyond rescue operations.24 fur seals (12 previously entangled, 12 control) at Seal Rocks have had trackers temporarily glued to their backs to compare the behaviour of seals entangled in marine plastic with healthy seals of the same sex and size. This allows researchers to measure whether rescue actually improves long-term outcomes.
The underlying cause is systemic.Seal Rocks has high concentrations of plastic marine debris, owing to its proximity to popular commercial and recreational fishing locations and urban areas.Most entanglement materials originated from commercial fisheries; most frequently entangling pups and juveniles. Young seals, naturally curious, are especially vulnerable.
What becomes apparent is that targeted rescue, while valuable, is a treatment symptom rather than a cure.21% of scats from Seal Rocks contain plastic, mostly microplastics of clothing filaments confirming that the fur seals are ingesting plastics from the environment. The broader challenge—preventing debris from entering the ocean in the first place—requires coordination across fishing industry practices, waste management, and community behaviour.
New knowledge and data is being used to drive changes to Government regulations to better protect seals.The teams are also working with FishCare Victoria on a community education and behaviour change campaign, targeting recreational fishing and wider community.The Phillip Island Nature Parks and South East Trawl Fishing Industry Association are rolling out 100 weather-proof bins for commercial fishing boats across Victoria, to stop net fragments and rubbish from being lost overboard.
The technology represents genuine progress: finding entangled seals before they die. But the fact that such innovation is necessary at all reflects the scale of human-generated marine pollution and decades of inadequate waste management at sea. The thermal drones are not a fix; they are a lifeline while deeper changes take hold. The research team's effort to measure and document long-term impacts of entanglement, rather than simply assuming rescue solves the problem, also shows scientific discipline in an area often driven by urgency and emotion.
For Australian policymakers, the case is instructive: visible, targeted interventions earn funding and public support. But lasting solutions require less photogenic investments in fisheries regulation, industrial waste capture, and behaviour change.Shared resources are being developed with Zoos Victoria, the University of Sydney and University of Melbourne, Victorian Fisheries Authority, DEECA, Parks Victoria, Bass Coast Shire and other stakeholders. The collaboration suggests that when government agencies, research institutions, and industry align, progress can follow.