As the light constantly sweeps back and forth, the only thing breaking the silence of a still Winter night in far north Queensland is the buzzing of the boat motor slowly pushing us downstream.
What we're looking for, Queensland's principal wildlife officer Matt Brien tells me, is the one "chink in the armour" of an animal whose reputation is largely centred on camouflage and stealth.
"There," he says quietly less than fifteen minutes after the boat entered the water.
"You've got a nice big eye shine down there, see that?"
A tiny, red reflection, no more remarkable than a dim laser pointer, is shining back as our "spotter", Dr Laurence Taplin, hovers his spotlight over an area near the bank.
"It seems to not stun them but make them stop," Dr Brien says.
"It's why we can catch them at night a lot easier."
This method for surveying crocodile populations hasn't changed much since the 70s. It's been used in Queensland, the Northern Territory, Western Australia and abroad.
Dr Brien has been appointed to lead Queensland's first comprehensive crocodile population survey in well over a decade and tonight his team is continuing its reconnaissance work ahead of the official study.
Just as we get closer to the red reflection, it dips underwater and vanishes.
"A lot of these rivers in the urban areas they tend to be quite wary," Dr Brien says, adding it's usually the small crocs that they can get closest to.
Dr Taplin, who worked on surveys in the 80s, can estimate the size of the animal based on its head, which is one seventh the total length.
After we've spotted our first croc, the red glow appears in the distance about every ten minutes.
I become acutely aware of the seemingly short distance between where I'm sitting near the side of the boat and the surface of the water.
The boat, at 4.3m, is not big enough to make an amateur like myself comfortable, particularly given horror movies have taught me that crocodiles won't hesitate in upturning a vessel to get a meal.
"In a boat like this, you're relatively secure," Dr Brien says before deconstructing my misguided fear that every croc in the river is waiting for its chance to pounce.
"They're not a lion or a predator that likes to chase down prey. I wouldn't say lazy, but they tend to wait for the food to come to them."
As long as your boat is moving, you're probably safe, he says, adding: "Bottom line, keep your arms and legs inside the boat."
While the crocs are certainly not stalking us, they can learn to associate people with food. A recent attack on Lizard Island by a 2.5m animal gave rise to the need for removal because the victim's injuries pointed to a predatory attack.
"When we located that animal he was still hanging around at the clubhouse near where people swim every day and he was raising himself out of the water, which is a sign of aggression," Dr Brien says.
"That animal was posing a serious threat ... it would have without a doubt attacked someone else."
It's not long before we get close enough for me to make out a croc figure floating in the water, unperturbed by the spotlight in its face. Most are only a couple of feet long, while some are mere hatchlings playfully demonstrating their buoyancy.
The need to survey Queensland's croc population was thrown into the public domain when NSW woman Cindy Waldron, 46, was taken at Thornton Beach, north of Cairns, just over a month ago.
The state government was forced to admit it didn't know "with enough scientific certainty" whether croc numbers were rising or falling. In the NT, annual surveys mean authorities have a handle on what the population is doing and can manage it accordingly.
"In light of a suspected crocodile attack in the Daintree we need to know," Environment Minister Dr Steven Miles said as he announced a $5.8 million crocodile management review just days after Ms Waldron's death.
But according to Matt Brien, preparation for a major survey had been underway for months before the tragedy in response to both growing community pressure and in the hope of funding being secured.
The department, he says, "copped a lot of heat" because there had been a number of reports of crocodiles in the Cape Tribulation area prior to Ms Waldron's fateful late-night swim. They were not removed.
"The interesting thing was the one that took the lady nobody ever reported to us, because they weren't worried about it," Dr Brien explains.
The animals that you see are the tip of the iceberg, he says.
"Quite often it's the one that you're not seeing that's going to be the problem."
Ms Waldron had decided to go for a risky beach adventure when she was dragged under the water as a friend watched in horror.
The incident prompted federal MP Bob Katter to call for croc-hunting safaris, while his fellow North Queensland MP Warren Entsch, in perhaps the most unsympathetic and ill-timed reaction, said it was not possible to "legislate against human stupidity".
Dr Taplin tells me croc safety messages haven't changed much since his survey.
"I think what has changed is the population in Queensland," he says.
"The human population in Queensland has grown a good deal over the years and so the extent to which people are likely to bump into crocodiles has increased."
"The need for public awareness has increased."
Dr Brien says if an animal isn't being aggressive, sometimes it's better to leave it because their presence works much better as a deterrent than the abundance of signs in the tropical north.
"Signs - they're towel racks to a lot of people, they just ignore it. But a big crocodile that's visible on a bank is a pretty good message."
There have been roughly 34 attacks in Queensland since 1971 and one-third have been fatal.
Since the mid-90s a rise in the number has been made up mostly of non-fatal attacks, but contrary to popular belief most of the victims - 75 per cent - aren't backpackers or tourists, but local men.
"We do a lot of schools and community groups, but when our primary statistic is local men, how do you better communicate the messages to them?" Dr Brien says.
"Maybe we can't, but we need to try."
President of the Queensland Crocodile Conservation and Protection Society Dean Adermann, who was one of a handful of stakeholders to take part in consultation sessions with Dr Brien this week as part of the review, says Queenslanders have become complacent.
"Because they don't see a croc there they think there's none here anymore," he says.
Tour operators up and down the coast have told him they've not noticed any increase in croc numbers in 15 years.
Mr Adermann pushed for better education measures during his consultation, including TV commercials and brochures in all hotels.
Back on the Russell, we've been out for close to two hours and have spotted about a dozen crocs over 10-12 kilometres, in line with what the team expected to find.
The population here is "healthy", Dr Brien says.
When Dr Taplin surveyed the same river in the 80s, he saw just two crocs over double that distance, but the results were highly variable and other waterways had much greater densities.
The population back then was only just recovering from commercial hunting. Another survey in the 1990s found it had made a "modest recovery". Since then, we've had no idea what the numbers are doing.
It's possible, however, to draw conclusions about the numbers based on attack data.
Across the rise in non-fatal attacks, the animal responsible has been about 2.5m. The average size for a fatal attack is 4m.
"What you can gather out of that is there's enough crocodiles of that size range and around people to result in that number of attacks," Dr Brien says.
"Is there an increase in the number of crocodiles?"
"There could potentially be that occurring and this monitoring will show us that."